Friday, August 31, 2012

NASA's Dawn Prepares for Trek Toward Dwarf Planet

NASA's Dawn spacecraft arrived at the giant asteroid Vesta on July 15, 2011 PDT (July 16, 2011 EDT) and is set to depart on Sept. 4, 2012 PDT (Sept. 5 EDT). Image credit: NASA/JPL-Caltech.
Larger view

Dawn Spacecraft's Farewell Portrait of Giant Asteroid Vesta

PASADENA, Calif. - NASA's Dawn spacecraft is on track to become the first probe to orbit and study two distant solar system destinations, to help scientists answer questions about the formation of our solar system. The spacecraft is scheduled to leave the giant asteroid Vesta on Sept. 4 PDT (Sept. 5 EDT) to start its two-and-a-half-year journey to the dwarf planet Ceres.

Dawn began its 3-billion-mile (5-billion kilometer) odyssey to explore the two most massive objects in the main asteroid belt in 2007. Dawn arrived at Vesta in July 2011 and will reach Ceres in early 2015. Dawn's targets represent two icons of the asteroid belt that have been witness to much of our solar system's history.

To make its escape from Vesta, the spacecraft will spiral away as gently as it arrived, using a special, hyper-efficient system called ion propulsion. Dawn's ion propulsion system uses electricity to ionize xenon to generate thrust. The 12-inch-wide ion thrusters provide less power than conventional engines, but can maintain thrust for months at a time.

"Thrust is engaged, and we are now climbing away from Vesta atop a blue-green pillar of xenon ions," said Marc Rayman, Dawn's chief engineer and mission director, at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are feeling somewhat wistful about concluding a fantastically productive and exciting exploration of Vesta, but now have our sights set on dwarf planet Ceres.

Dawn's orbit provided close-up views of Vesta, revealing unprecedented detail about the giant asteroid. The mission revealed that Vesta completely melted in the past, forming a layered body with an iron core. The spacecraft also revealed the scarring from titanic collisions Vesta suffered in its southern hemisphere, surviving not one but two colossal impacts in the last two billion years. Without Dawn, scientists would not have known about the dramatic troughs sculpted around Vesta, which are ripples from the two south polar impacts.

"We went to Vesta to fill in the blanks of our knowledge about the early history of our solar system," said Christopher Russell, Dawn's principal investigator, based at the University of California Los Angeles (UCLA). "Dawn has filled in those pages, and more, revealing to us how special Vesta is as a survivor from the earliest days of the solar system. We can now say with certainty that Vesta resembles a small planet more closely than a typical asteroid."

The mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif., for the agency's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Ala.

UCLA is responsible for the overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission's team. The California Institute of Technology in Pasadena manages JPL for NASA.

For information about the Dawn mission, visit: http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov .

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington

dwayne.c.brown@nasa.gov

NGC 1929 in N44: A Surprisingly Bright Superbubble

Credit X-ray: NASA/CXC/U.Mich./S.Oey,

This composite image shows a superbubble in the Large Magellanic Cloud (LMC), a small satellite galaxy of the Milky Way, located about 160,000 light years from Earth. Many new stars, some of them very massive, are forming in the star cluster NGC 1929, which is embedded in the nebula N44. The massive stars produce intense radiation, expel matter at high speeds, and race through their evolution to explode as supernovas. The winds and supernova shock waves carve out huge cavities called superbubbles in the surrounding gas. X-rays from NASA's Chandra X-ray Observatory (blue) show hot regions created by these winds and shocks, while infrared data from NASA's Spitzer Space Telescope (red) outline where the dust and cooler gas are found. The optical light from the 2.2m Max-Planck-ESO telescope (yellow) in Chile shows where ultraviolet radiation from hot, young stars is causing gas in the nebula to glow.

A long-running problem in high-energy astrophysics has been that some superbubbles in the LMC, including N44, give off a lot more X-rays than expected from models of their structure. A Chandra study published in 2011 showed that there are two extra sources of the bright X-ray emission: supernova shock waves striking the walls of the cavities, and hot material evaporating from the cavity walls. The observations show no evidence for an enhancement of elements heavier than hydrogen and helium in the cavities, thus ruling out this possibility as an explanation for the bright X-ray emission. This is the first time that the data have been good enough to distinguish between different sources of the X-rays produced by superbubbles.

The Chandra study of N44 and another superbubble in the LMC was led by Anne Jaskot from the University of Michigan in Ann Arbor. The co-authors were Dave Strickland from Johns Hopkins University in Baltimore, MD, Sally Oey from University of Michigan, You-Hua Chu from University of Illinois and Guillermo Garcia-Segura from Instituto de Astronomia-UNAM in Ensenada, Mexico.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

Fast Facts for NGC 1929:

Release Date: August 30, 2012
Scale: Image is 25 arcmin across (1200 light years)
Category:
Normal Stars & Star Clusters
Coordinates: (J2000) RA 05h 22m 17.00s | Dec -67° 76' 38.00"
Constellation:
Dorado
Observation Date: Sept 22, 2002
Observation Time: 5 hours 33 min.
Obs. ID: 3356
Instrument:
ACIS
References: Jaskot, A.E. et al 2011, ApJ, 729, 28; arXiv:1101.0280

Thursday, August 30, 2012

NASA's WISE Survey Uncovers Millions of Black Holes

With its all-sky infrared survey, NASA's Wide-field Infrared Survey Explorer, or WISE, has identified millions of quasar candidates. Image credit: NASA/JPL-Caltech/UCLA. Full image and caption - View media telecon images


PASADENA, Calif. -- NASA's Wide-field Infrared Survey Explorer (WISE) mission has led to a bonanza of newfound supermassive black holes and extreme galaxies called hot DOGs, or dust-obscured galaxies.

Images from the telescope have revealed millions of dusty black hole candidates across the universe and about 1,000 even dustier objects thought to be among the brightest galaxies ever found. These powerful galaxies, which burn brightly with infrared light, are nicknamed hot DOGs.

"WISE has exposed a menagerie of hidden objects," said Hashima Hasan, WISE program scientist at NASA Headquarters in Washington. "We've found an asteroid dancing ahead of Earth in its orbit, the coldest star-like orbs known and now, supermassive black holes and galaxies hiding behind cloaks of dust."

WISE scanned the whole sky twice in infrared light, completing its survey in early 2011. Like night-vision goggles probing the dark, the telescope captured millions of images of the sky. All the data from the mission have been released publicly, allowing astronomers to dig in and make new discoveries.

The latest findings are helping astronomers better understand how galaxies and the behemoth black holes at their centers grow and evolve together. For example, the giant black hole at the center of our Milky Way galaxy, called Sagittarius A*, has 4 million times the mass of our sun and has gone through periodic feeding frenzies where material falls towards the black hole, heats up and irradiates its surroundings. Bigger central black holes, up to a billion times the mass of our sun, may even shut down star formation in galaxies.

In one study, astronomers used WISE to identify about 2.5 million actively feeding supermassive black holes across the full sky, stretching back to distances more than 10 billion light-years away. About two-thirds of these objects never had been detected before because dust blocks their visible light. WISE easily sees these monsters because their powerful, accreting black holes warm the dust, causing it to glow in infrared light.

"We've got the black holes cornered," said Daniel Stern of NASA's Jet Propulsion Laboratory, Pasadena, Calif., lead author of the WISE black hole study and project scientist for another NASA black-hole mission, the Nuclear Spectroscopic Telescope Array (NuSTAR). "WISE is finding them across the full sky, while NuSTAR is giving us an entirely new look at their high-energy X-ray light and learning what makes them tick."

In two other WISE papers, researchers report finding what are among the brightest galaxies known, one of the main goals of the mission. So far, they have identified about 1,000 candidates.

These extreme objects can pour out more than 100 trillion times as much light as our sun. They are so dusty, however, that they appear only in the longest wavelengths of infrared light captured by WISE. NASA's Spitzer Space Telescope followed up on the discoveries in more detail and helped show that, in addition to hosting supermassive black holes feverishly snacking on gas and dust, these DOGs are busy churning out new stars.

"These dusty, cataclysmically forming galaxies are so rare WISE had to scan the entire sky to find them," said Peter Eisenhardt, lead author of the paper on the first of these bright, dusty galaxies, and project scientist for WISE at JPL. "We are also seeing evidence that these record setters may have formed their black holes before the bulk of their stars. The 'eggs' may have come before the 'chickens.'"

More than 100 of these objects, located about 10 billion light-years away, have been confirmed using the W.M. Keck Observatory on Mauna Kea, Hawaii, as well as the Gemini Observatory in Chile, Palomar's 200-inch Hale telescope near San Diego, and the Multiple Mirror Telescope Observatory near Tucson, Ariz.

The WISE observations, combined with data at even longer infrared wavelengths from Caltech's Submillimeter Observatory atop Mauna Kea, revealed that these extreme galaxies are more than twice as hot as other infrared-bright galaxies. One theory is their dust is being heated by an extremely powerful burst of activity from the supermassive black hole.

"We may be seeing a new, rare phase in the evolution of galaxies," said Jingwen Wu of JPL, lead author of the study on the submillimeter observations. All three papers are being published in the Astrophysical Journal.

The three technical journal articles, including PDFs, can be found at http://arxiv.org/abs/1205.0811, http://arxiv.org/abs/1208.5517 and http://arxiv.org/abs/1208.5518 .

JPL manages and operates WISE for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing and archiving take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

More information is online at http://www.nasa.gov/wise, http://wise.astro.ucla.edu and http://jpl.nasa.gov/wise .


Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

Whitney.clavin@jpl.nasa.gov


NASA's Kepler Discovers Multiple Planets Orbiting a Pair of Stars

Sharing the Light of Two Suns: This artist's concept illustrates Kepler-47, the first transiting circumbinary system. Credit: NASA/JPL-Caltech/T. Pyle. Click here for multiple resolutions and full caption.

Orbiting in the Habitable Zone of Two Suns: This diagram compares our own solar system to Kepler-47, a double-star system containing two planets, one orbiting in the so-called "habitable zone." Credit: NASA/JPL-Caltech/T. Pyle. Click here for multiple resolutions and full caption.

The planets Kepler-47b and Kepler-47c: Kepler-47b has three times the radius of earth and orbits the pair of stars in less than 50 days while Kepler-47c is thought to be a gaseous giant, slightly larger than Neptune with an orbital period of 303 days. Credit: NASA/JPL-Caltech/T. Pyle. Click here for multiple resolutions and full caption.

Coming less than a year after the announcement of the first circumbinary planet, Kepler-16b, NASA's Kepler mission has discovered multiple transiting planets orbiting two suns for the first time. This system, known as a circumbinary planetary system, is 4,900 light-years from Earth in the constellation Cygnus.

This discovery proves that more than one planet can form and persist in the stressful realm of a binary star and demonstrates the diversity of planetary systems in our galaxy.

Astronomers detected two planets in the Kepler-47 system, a pair of orbiting stars that eclipse each other every 7.5 days from our vantage point on Earth. One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than 1 percent as bright.

"In contrast to a single planet orbiting a single star, the planet in a circumbinary system must transit a 'moving target.' As a consequence, time intervals between the transits and their durations can vary substantially, sometimes short, other times long," said Jerome Orosz, associate professor of astronomy at San Diego State University and lead author of the paper. "The intervals were the telltale sign these planets are in circumbinary orbits."

The inner planet, Kepler-47b, orbits the pair of stars in less than 50 days. While it cannot be directly viewed, it is thought to be a sweltering world, where the destruction of methane in its super-heated atmosphere might lead to a thick haze that could blanket the planet. At three times the radius of Earth, Kepler-47b is the smallest known transiting circumbinary planet.

The outer planet, Kepler-47c, orbits its host pair every 303 days, placing it in the so-called "habitable zone," the region in a planetary system where liquid water might exist on the surface of a planet. While not a world hospitable for life, Kepler-47c is thought to be a gaseous giant slightly larger than Neptune, where an atmosphere of thick bright water-vapor clouds might exist.

"Unlike our sun, many stars are part of multiple-star systems where two or more stars orbit one another. The question always has been -- do they have planets and planetary systems? This Kepler discovery proves that they do," said William Borucki, Kepler mission principal investigator at NASA's Ames Research Center in Moffett Field, Calif. "In our search for habitable planets, we have found more opportunities for life to exist."

To search for transiting planets, the research team used data from the Kepler space telescope, which measures dips in the brightness of more than 150,000 stars. Additional ground-based spectroscopic observations using telescopes at the McDonald Observatory at the University of Texas at Austin helped characterize the stellar properties. The findings are published in the journal Science.

"The presence of a full-fledged circumbinary planetary system orbiting Kepler-47 is an amazing discovery," said Greg Laughlin, professor of Astrophysics and Planetary Science at the University of California in Santa Cruz. "These planets are very difficult to form using the currently accepted paradigm, and I believe that theorists, myself included, will be going back to the drawing board to try to improve our understanding of how planets are assembled in dusty circumbinary disks."

Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development.

Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's tenth Discovery Mission and funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

To download the full video please visit: http://www.nasa.gov/multimedia/videogallery/index.html?media_id=151299651 Credit: NASA/JPL-Caltech/T. Pyle

Contacts:

Michele Johnson
Ames Research Center, Moffett Field, Calif.
650-604-6982

michele.johnson@nasa.gov

J.D. Harrington
Headquarters, Washington
202-358-5241

j.d.harrington@nasa.gov

Wednesday, August 29, 2012

Sweet Result from ALMA

PR Image eso1234a
Sugar molecules in the gas surrounding a young Sun-like star

PR Image eso1234b
Artist’s impression of glycolaldehyde molecules

PR Image eso1234c
Infrared view of the Rho Ophiuchi star-forming region

PR Image eso1234d
IRAS 16293-2422 in the constellation of Ophiuchus

Videos

PR Video eso1234a
Sugar molecules in the gas surrounding a young Sun-like star (zoom)

PR Video eso1234b
Artist’s impression of glycolaldehyde molecules

Building blocks of life found around young star

A team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has spotted sugar molecules in the gas surrounding a young Sun-like star. This is the first time sugar been found in space around such a star, and the discovery shows that the building blocks of life are in the right place, at the right time, to be included in planets forming around the star
.

The astronomers found molecules of glycolaldehyde — a simple form of sugar [1] — in the gas surrounding a young binary star, with similar mass to the Sun, called IRAS 16293-2422. Glycolaldehyde has been seen in interstellar space before [2], but this is the first time it has been found so near to a Sun-like star, at distances comparable to the distance of Uranus from the Sun in the Solar System. This discovery shows that some of the chemical compounds needed for life existed in this system at the time of planet formation [3].

“In the disc of gas and dust surrounding this newly formed star, we found glycolaldehyde, which is a simple form of sugar, not much different to the sugar we put in coffee,” explains Jes Jørgensen (Niels Bohr Institute, Denmark), the lead author of the paper. “This molecule is one of the ingredients in the formation of RNA, which — like DNA, to which it is related — is one of the building blocks of life.”

The high sensitivity of ALMA — even at the technically challenging shortest wavelengths at which it operates — was critical for these observations, which were made with a partial array of antennas during the observatory’s Science Verification phase [4].

“What it is really exciting about our findings is that the ALMA observations reveal that the sugar molecules are falling in towards one of the stars of the system,” says team member Cécile Favre (Aarhus University, Denmark). “The sugar molecules are not only in the right place to find their way onto a planet, but they are also going in the right direction.”

The gas and dust clouds that collapse to form new stars are extremely cold [5] and many gases solidify as ice on the particles of dust where they then bond together and form more complex molecules. But once a star has been formed in the middle of a rotating cloud of gas and dust, it heats the inner parts of the cloud to around room temperature, evaporating the chemically complex molecules, and forming gases that emit their characteristic radiation as radio waves that can be mapped using powerful radio telescopes such as ALMA.

IRAS 16293-2422 is located around 400 light-years away, comparatively close to Earth, which makes it an excellent target for astronomers studying the molecules and chemistry around young stars. By harnessing the power of a new generation of telescopes such as ALMA, astronomers now have the opportunity to study fine details within the gas and dust clouds that are forming planetary systems.

"A big question is: how complex can these molecules become before they are incorporated into new planets? This could tell us something about how life might arise elsewhere, and ALMA observations are going to be vital to unravel this mystery,” concludes Jes Jørgensen.

The work is described in a paper to appear in the journal Astrophysical Journal Letters.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Notes

[1] Sugar is the common name for a range of small carbohydrates (molecules containing carbon, hydrogen and oxygen, typically with a hydrogen:oxygen atomic ratio of 2:1, as in water). Glycolaldehyde has the chemical formula C2H4O2. The sugar commonly used in food and drink is sucrose, which is a larger molecule than glycolaldehyde, and another example of this set of compounds.

[2] Glycolaldehyde has been detected in two places in space so far — first towards the Galactic Centre cloud Sgr B2, using the National Science Foundation's (NSF) 12 Meter Telescope at Kitt Peak (USA) in 2000, and with the NSF's Robert C. Byrd Green Bank Telescope (also USA) in 2004, and in the high-mass hot molecular core G31.41+0.31 using the IRAM Plateau de Bure Interferometer (France) in 2008.

[3] Accurate laboratory measurements of the characteristic wavelengths of radio waves emitted by glycolaldehyde were critical for the team’s identification of the molecule in space. In addition to the glycolaldehyde, IRAS 16293-2422 is also known to harbour a number of other complex organic molecules, including ethylene glycol, methyl formate and ethanol.

[4] Early scientific observations with a partial array of antennas began in 2011 (see eso1137). Both before and after this, a range of Science Verification observations have been performed to demonstrate that ALMA is capable of producing data of the required quality, and the data produced have been made publicly available. The results described here use some of these Science Verification data. Construction of ALMA will be completed in 2013, when 66 high-precision antennas will be fully operational.

[5] They are usually around 10 degrees above absolute zero: about –263 degrees Celsius.

More information

This research was presented in a paper “Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA”, by Jørgensen et al., to appear in Astrophysical Journal Letters.

The team is composed of Jes K. Jørgensen (University of Copenhagen, Denmark), Cécile Favre (Aarhus University, Denmark), Suzanne E. Bisschop (University of Copenhagen), Tyler L. Bourke (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), Ewine F. van Dishoeck (Leiden Observatory, The Netherlands; Max-Planck-Institut für extraterrestrische Physik, Garching, Germany) and Markus Schmalzl (Leiden Observatory).

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links

Contacts

Jes K. Jørgensen
Niels Bohr Institute, University of Copenhagen
Copenhagen, Denmark
Tel: +45 4250 9970
Email
: jeskj@nbi.dk

Ewine van Dishoeck
Leiden Observatory
Leiden, Netherlands
Tel: +31 71 5275814
Email:
ewine@strw.leidenuniv.nl

Douglas Pierce-Price, Public Information Officer
ESO
Garching bei München, Germany
Tel: +49 89 3200 6759
Email:
dpiercep@eso.org

Doomsday 2012 Fact Sheet


There is widespread and unnecessary fear of doomsday on December 21, 2012. Some people worry about a Maya prophesy of the end of the world, others fear a variety of astronomical threats such as collision with a rogue planet. Opinion polls suggest that one in ten Americans worry about whether they will survive past Dec 21 of this year, and middle-school teachers everywhere report that many of their students are fearful of a coming apocalypse. Following are brief facts that address these doomsday fears. For more comprehensive discussions and lists of resources please consult these three websites:

***

Mayan Calendar: The Maya calendar, which is made up different cycles of day counts, does not end this year. Rather, one cycle of 144,000 days (394 years) ends and the next cycle begins.

Mayan Prophecy: The ancient Maya did not predict the end of the world or any disaster in December 2012. Such doomsday predictions are a modern hoax.

Planet Nibiru: Nibiru is probably the minor name of a god found in ancient Mesopotamian writing. There is no planet named Nibiru, and the fictional books by economist Zecharia Sitchin about a civilization on this planet are a hoax.

Rogue Planet Headed for Earth: For the past decade there have been reports of a rogue object (Planet X, or Nibiru, or Hercubolus, or even Comet Elenin) that will collide with Earth in December 2012. These claims are not true. If such a threatening world existed, it would be one of the brightest objects in the sky, and astronomers would have been tracking it for years. If it existed, its gravity would be distorting the orbits of planets, especially Mars and Earth. Astronomers know that it does not exist.

Planet Alignments: There is no alignment of planets in Dec 2012. There is an approximate lining up of the Earth and Sun and the center of our Galaxy in late December, but this happens every year. In any case, planet alignments have no effect on the Earth.

Pole Shift: There is nothing strange this year about either the magnetic poles or the rotational poles of the Earth. The magnetic polarity changes every million years or so, but that is not happening now, and it probably takes thousands of years when it does happen. A sudden change in the rotational axis has never happened and is not possible. If there were any change in the Earth’s rotation, it would be instantly apparent by failure of our GPS systems.

Increasing Disasters: Our planet is behaving normally in 2012, although we see more and more news stories about natural disasters. There has been no increase in earthquakes or volcanic eruptions. There has been an increase in extreme weather, including both droughts and floods, which are partly attributable to global warming, but this has nothing to do with a 2012 doomsday.

Solar Outbursts:
The Sun’s ongoing 11-year activity cycle is expected to peak in 2013, not 2012. Solar outbursts (flares and CMEs) can damage orbiting satellites but will not hurt us on the surface. The strength of the 2013 solar maximum is predicted to be lower than average, not higher.

Bunker Conspiracy:
Accusations of a massive government cover-up are nonsense. No government could hide an incoming planet or silence hundreds of thousands of scientists. Rumors that huge bunkers have been built in the U.S. or elsewhere to shelter the elite are lies. Apparently a few people are building private shelters, but their fear of 2012 is misplaced and they are wasting their money.

Scaring Children: The group most vulnerable to doomsday claims is children. Teachers report that many of their students are frightened and some are even considering suicide. This is the most tragic consequence of the 2012 hoax.

The End of the World: The idea of the sudden end of the world by any cause is absurd. The Earth has been here for more than 4 billion years, and it will be several more billion years before the gradual brightening of the Sun makes our planet unlivable. Meanwhile there is no known astronomical or geological threat that could destroy the Earth.

Cosmophobia: Many young people write to me that they are scared of astronomy. When they read about some new discovery, the first thing they think is that it might hurt them, even if it is happening in a distant galaxy. There is no reason for such fears, which I call cosmophobia (fear of the universe). This rash of concern seems to be the result of too many conspiracy theories and sensational stories featured on the Internet and irresponsible news outlets. Astronomical objects are so distant that they cannot threaten the Earth. Please don’t be afraid of the Sun or the planets or comets or asteroids. The universe is not your enemy.

A Collection of Ancient Stars

M 56 - NGC 6779
Credit: NASA & ESA
Acknowledgement: Gilles Chapdelaine

The NASA/ESA Hubble Space Telescope has produced this beautiful image of the globular cluster Messier 56 (also known as M 56 or NGC 6779), which is located about 33 000 light years away from the Earth in the constellation of Lyra (The Lyre). The cluster is composed of a large number of stars, tightly bound to each other by gravity.

However, this was not known when Charles Messier first observed it in January 1779. He described Messier 56 as “a nebula without stars”, like most globular clusters that he discovered — his telescope was not powerful enough to individually resolve any of the stars visible here, making it look like a fuzzy ball through his telescope’s eyepiece. We clearly see from Hubble’s image how the development of technology over the years has helped our understanding of astronomical objects.

Astronomers typically infer important properties of globular clusters by looking at the light of their constituent stars. But they have to be very careful when they observe objects like Messier 56, which is located close to the Galactic plane. This region is crowded by “field-stars”, in other words, stars in the Milky Way that happen to lie in the same direction but do not belong to the cluster. These objects can contaminate the light, and hence undermine the conclusions reached by astronomers.

A tool often used by scientists for studying stellar clusters is the colour-magnitude (or Hertzsprung-Russell) diagram. This chart compares the brightness and colour of stars – which in turn, tells scientists what the surface temperature of a star is.

By comparing high quality observations taken with the Hubble Space Telescope with results from the standard theory of stellar evolution, astronomers can characterise the properties of a cluster. In the case of Messier 56, this includes its age, which at 13 billion years is approximately three times the age of the Sun. Furthermore, they have also been able to study the chemical composition of Messier 56. The cluster has relatively few elements heavier than hydrogen and helium, typically a sign of stars that were born early in the Universe’s history, before many of the elements in existence today were formed in significant quantities.

Astronomers have found that the majority of clusters with this type of chemical makeup lie along a plane in the Milky Way’s halo. This suggests that such clusters were captured from a satellite galaxy, rather than being the oldest members of the Milky Way's globular cluster system as had been previously thought.

This image consists of visible and near-infrared exposures from Hubble’s Advanced Camera for Surveys. The field of view is approximately 3.3 by 3.3 arcminutes.

A version of this image was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant Gilles Chapdelaine. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed and the results will be published soon.

Source: ESA/Hubble - Space telescope

Tuesday, August 28, 2012

Space-Warping White Dwarfs Produce Gravitational Waves

An artist's conception of J0651 with ripples to demonstrate how the white dwarf pair is emitting gravitational waves. Credit: NASA. High Resolution Image (jpg)

Cambridge, MA - Gravitational waves, much like the recently discovered Higgs boson, are notoriously difficult to observe. Scientists first detected these ripples in the fabric of space-time indirectly, using radio signals from a pulsar-neutron star binary system. The find, which required exquisitely accurate timing of the radio signals, garnered its discoverers a Nobel Prize. Now a team of astronomers has detected the same effect at optical wavelengths, in light from a pair of eclipsing white dwarf stars.

"This result marks one of the cleanest and strongest detections of the effect of gravitational waves," said team member Warren Brown of the Smithsonian Astrophysical Observatory (SAO).

The team discovered the white dwarf pair last year. (White dwarfs are the remnant cores of stars like our Sun.) The system, called SDSS J065133.338+284423.37 (J0651 for short), contains two white dwarf stars so close together -- one-third of the Earth-moon distance -- that they make a complete orbit in less than 13 minutes.

"Every six minutes the stars in J0651 eclipse each other as seen from Earth, which makes for an unparalleled and accurate clock some 3,000 light-years away," said study lead author J.J. Hermes, a graduate student working with Professor Don Winget at The University of Texas at Austin.

Einstein's theory of general relativity predicts that moving objects create subtle ripples in the fabric of space-time, called gravitational waves. Gravitational waves should carry away energy, causing the stars to inch closer together and orbit each other faster and faster. The team was able to detect this effect in J0651.

"Compared to April 2011, when we discovered this object, the eclipses now happen six seconds sooner than expected," said team member Mukremin Kilic of The University of Oklahoma.

"This is a general relativistic effect you could measure with a wrist watch," added SAO's Warren Brown.

J0651 will provide an opportunity to compare future direct, space-based detection of gravitational waves with those inferred from the orbital decay, providing important benchmark tests of our understanding of the workings of gravity.

The team expects that the period will shrink more and more each year, with eclipses happening more than 20 seconds sooner than otherwise expected by May 2013. The stars will eventually merge, in two million years. Future observations will continue to measure the orbital decay of this system, and attempt to understand how tides affect the merger of such stars.

The team's results will be published in The Astrophysical Journal Letters and are available online.

This release is being issued jointly with The University of Texas at Austin.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462

daguilar@cfa.harvard.edu

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463

cpulliam@cfa.harvard.edu

Rebecca Johnson
University of Texas at Austin
512-475-6763

rjohnson@astro.as.utexas.edu

Monday, August 27, 2012

The PI's Perspective

New Horizons hopes to explore beyond Pluto,
into the ancient and unexplored Kuiper Belt

The Kuiper Belt at 20:
Paradigm Changes in Our Knowledge of the Solar System


New Horizons remains healthy and on course, now more than 24 times as far from the Sun as the Earth is. This summer’s spacecraft and payload checkout went extremely well, as did both major flight-software updates we loaded aboard New Horizons. And, the spacecraft’s rehearsal of the closest-approach day of the Pluto encounter went just about perfectly.

After finishing all of this at the beginning of July, we put New Horizons back into hibernation, and we’ve been cruising that way for almost eight weeks. As those who follow New Horizons on Twitter (@NewHorizons2015) know, every Monday New Horizons checks in with a beacon that tells us if all is well, or not. And almost every week we’ve been able to report a “green beacon Monday” to our 22,000-plus Twitter followers, indicating the spacecraft is in good health.

New Horizons will cruise quietly in hibernation until Jan. 6, 2013, when we wake it up for a month of complex activities, including some advance work on next summer’s checkout, and the third of the four major software upgrades needed before next summer’s on-spacecraft rehearsal of the nine days surrounding Pluto closest approach.

Since activity on New Horizons is pretty quiet right now, I’ll take this opportunity to mention that planetary science is celebrating the 20th anniversary of the discovery of the Kuiper Belt. That came in 1992, when the first Kuiper Belt Object (KBO) was discovered.

Actually, of course, the first object in the Kuiper Belt was discovered in 1930 — Pluto itself; and the second such object, Pluto’s giant moon Charon, was discovered in 1978. The Kuiper Belt was first postulated — most famously by Gerard Kuiper — by planetary scientists back in the 1930s, ‘40s and ‘50s. But it took until 1992 for technology to mature sufficiently enough to find another object (outside the Pluto system) orbiting the Sun beyond Neptune.

This plot shows one aspect of Kuiper Belt structure: Different numbers of bodies orbit at different distances. This graph includes just the known bodies, which make up a tiny fraction of the grand total. (Wikipedia)

Since 1992, more than 1,000 KBOs have been discovered. But only a tiny fraction of the sky has been surveyed for KBOs. It is estimated that more than 100,000 KBOs exist with diameters of 100 kilometers or larger, along with billions of smaller objects down to the size of cometary nuclei, just a kilometer or two across. (By comparison, Pluto is huge — its diameter is almost 2,400 kilometers, making a drive around its equator as far as from Manhattan to Moscow!)
Most of the known KBOs are just 100 to 300 kilometers across, about one-tenth of Pluto’s diameter. But some are smaller than 100 kilometers across, and some are larger than 300 kilometers across. In fact, there is great diversity among KBOs:
  • Some are red and some are gray;
  • The surfaces of some are covered in water ice, but others (like Pluto) have exotic volatile ices like methane and nitrogen;
  • Many have moons, though none with more known moons than Pluto;
  • Some are highly reflective (like Pluto), others have much darker surfaces;
  • Some have much lower densities than Pluto, meaning they are primarily made of ice. Pluto’s density is so high that we know its interior is about 70% rock in its interior; a few known KBOs are more dense than Pluto, and even rockier!

Some planets of the Kuiper Belt; note that since this diagram was made, we’ve learned that Eris is actually smaller than Pluto. (http://www.sollunaterra.webs.com)

But I don’t consider this surprising assortment of KBOs to be the most important contribution to our knowledge of the solar system that has come from telescope exploration of the Kuiper Belt. In my opinion, the three greatest solar system lessons we’ve learned from the Kuiper Belt are:
  • That our planetary system is much larger than we used to think. In fact, we were largely unaware of the Kuiper Belt — the largest structure in our solar system — until it was discovered 20 years ago. It’s akin to not having maps of the Earth that included the Pacific Ocean as recently as 1992!
  • That the locations and orbital eccentricities and inclinations of the planets in our solar system (and other solar systems as well) can change with time. This even creates whole flocks of migration of planets in some cases. We have firm evidence that many KBOs (including some large ones like Pluto), were born much closer to the Sun, in the region where the giant planets now orbit.
  • And, perhaps most surprisingly, that our solar system, and very likely very many others, was very good at making small planets, which dominate the planetary population! Today we know of more than a dozen dwarf planets in the solar system, and those dwarfs already outnumber the number of gas giants and terrestrial planets combined. But it is estimated that the ultimate number of dwarf planets we will discover in the Kuiper Belt and beyond may well exceed 10,000. Who knew? (And which class of planet is the misfit now?)

What an amazing set of paradigm shifts in our knowledge the Kuiper Belt has brought so far. Our quaint 1990s and earlier view of the solar system missed its largest structure! It didn’t know about the existence of dwarf planets, the most populous class of planet in our solar system —and very likely the galaxy. It didn’t even contemplate that dwarf planets would have such a wide range of colors, reflectivities, orbits and surface compositions. And it didn’t realize that the locations of most planets in our solar system today — even including some of the very largest planets — are different from where they were born.

Just imagine what our close flybys of the Pluto system and smaller KBOs, combined with new giant telescopes coming on line to probe the sky, will teach us about the Kuiper Belt in the next 20 years. It’s an exciting time, and its sometimes hard for me to believe after working on this since 1989, that our 2015 exploration of Pluto and its many moons is almost upon us—but it is!

Well, that’s my update for now. Thanks again for following our journey across the deep ocean of space, to a new planet and a truly new frontier.

Until I write again, I hope you’ll keep on exploring — just as we do!

Alan Stern

Saturday, August 25, 2012

Neil Armstrong, First Man on the Moon, Dies at 82

Former NASA astronaut Neil A. Armstrong was born in Wapakoneta,
Ohio, on August 5, 1930

Today we mourn the loss of a true hero and icon of a generation, if not an entire century: Neil Alden Armstrong, former NASA astronaut and first person to set foot on the Moon, has passed away due to complications from cardiovascular surgery. Armstrong had recently turned 82 years old on August 5. Project Apollo Archive.

Rest in Peace!

Friday, August 24, 2012

NASA Event to Discuss Black Holes and Extreme Objects

Artist's concept of the Wide-field Infrared Survey Explorer
Image credit: NASA/JPL-Caltech
Full image and caption

PADADENA, Calif. -- NASA will host a news teleconference at 10 a.m. PDT (1 p.m. EDT), Wednesday, Aug. 29, to announce new discoveries from its Wide-field Infrared Survey Explorer (WISE). The discoveries are related to the distant universe, including supermassive black holes and rare galaxies.

The briefing participants are:

-- Daniel Stern, astronomer, NASA's Jet Propulsion Laboratory, Pasadena, Calif.
-- Peter Eisenhardt, WISE project scientist, JPL
-- Jingwen Wu, astronomer, JPL
-- Rachel Somerville, astrophysics professor, Rutgers University, New Brunswick, N.J.

A link to the teleconference graphics will be available at the start of the event at www.nasa.gov/wise .

For live audio of the teleconference, visit http://www.nasa.gov/newsau

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-5241
Headquarters, Washington

j.d.harrington@nasa.gov


Thursday, August 23, 2012

Supernovae of the Same Brightness, Cut From Vastly Different Cosmic Cloth


Berkeley Lab researchers make historic observation
of rare Type 1a Supernova


Berkeley, Calif., Aug 23, 2012—Exploding stars called Type 1a supernova are ideal for measuring cosmic distance because they are bright enough to spot across the Universe and have relatively the same luminosity everywhere. Although astronomers have many theories about the kinds of star systems involved in these explosions (or progenitor systems), no one has ever directly observed one—until now.

In the August 24 issue of Science, the multi-institutional Palomar Transient Factory (PTF) team presents the first-ever direct observations of a Type 1a supernova progenitor system. Astronomers have collected evidence indicating that the progenitor system of a Type 1a supernova, called PTF 11kx, contains a red giant star. They also show that the system previously underwent at least one much smaller nova eruption before it ended its life in a destructive supernova. The system is located 600 million light years away in the constellation Lynx.

By comparison, indirect observations of another Type 1a supernova progenitor system (called SN 2011fe, conducted by the PTF team last year) showed no evidence of a red giant star. Taken together, these observations unequivocally show that just because Type 1a supernovae look the same, that doesn’t mean they are all born the same way.

“We know that Type 1a supernovae vary slightly from galaxy to galaxy, and we’ve been calibrating for that, but this PTF 11kx observation is providing the first explanation of why this happens,” says Peter Nugent, a senior scientist at the Lawrence Berkeley National Laboratory (Berkeley Lab) and a co-author on the paper. “This discovery gives us an opportunity to refine and improve the accuracy of our cosmic measurements.”



Artist’s conception of a binary star system that produces recurrent novae, and ultimately, the supernova PTF 11kx. A red giant star (foreground) loses some of its outer layers through a stellar wind, and some of it forms a disk around a companion white dwarf star. This material falls onto the white dwarf, causing it to experience periodic nova eruptions every few decades. When the mass builds up to near the ultimate limit a white dwarf star can take, it explodes as a Type Ia supernova, destroying the white dwarf. (Animation credit: Romano Corradi and the Instituto de Astrofísica de Canarias)

“It’s a total surprise to find that thermonuclear supernovae, which all seem so similar, come from different kinds of stars,” says Andy Howell, a staff scientist at the Las Cumbres Observatory Global Telescope Network (LCOGT) and a co-author on the paper. “How could these events look so similar, if they had different origins?”

The supernova PTF 11kx can be seen as the blue dot on the galaxy. The image was taken when the supernova was near maximum brightness by the Faulkes Telescope North. The system is located approximately 600 million light years away in the constellation Lynx. (BJ Fulton, Las Cumbres Observatory Global Telescope Network)

A One in a Thousand Discovery, Powered by Supercomputers

Although Type 1a supernovae are rare, occurring maybe once or twice a century in a typical galaxy, Nugent notes that finding a Type 1a progenitor system like PTF 11kx is even more rare. “You maybe find one of these systems in a sample of 1,000 Type 1a supernovae,” he says. “The Palomar Transient Factory Real-Time Detection Pipeline was crucial to finding PTF 11kx.”

The PTF survey uses a robotic telescope mounted on the 48-inch Samuel Oschin Telescope at Palomar Observatory in southern California to scan the sky nightly. As the observations are taken, the data travels more than 400 miles via high-speed networks–including the National Science Foundation’s High Performance Wireless Research and Education Network and the Department of Energy’s Energy Sciences Network (ESnet)–to the National Energy Research Scientific Computing Center (NERSC), located at Berkeley Lab. There, the Real-time Transient Detection Pipeline uses supercomputers, a high-speed parallel filesystem and sophisticated machine learning algorithms to sift the data and identify events for scientists to follow up on.

According to Nugent, the pipeline detected the supernova on January 16, 2011. He and UC Berkeley postdoctoral researcher Jeffrey Silverman immediately followed up on the event with spectroscopy observations from the Shane telescope at the University of California’s Lick Observatory. These observations revealed incredibly strong calcium signals in the gas and dust surrounding the supernova, which is extremely unusual.

The signals were so peculiar that Nugent and his UC Berkeley colleagues, Alex Filippenko and Joshua Bloom, triggered a Target of Opportunity (ToO) observation using the Keck Telescope in Hawaii. “We basically called up a fellow UC observer and interrupted their observations in order to get time critical spectra,” Nugent explains.

From the Keck observations, astronomers noticed that the clouds of gas and dust surrounding PTF 11kx were moving too slowly to be coming from the recent supernova, but moving too quickly to be stellar wind. They suspected that maybe the star erupted, or went nova, previously propelling a shell of material outwards. The material, they surmised, must be slowing down as it collided with wind from a nearby red giant star. But for this theory to be true, the material from the recent supernova should eventually catch up and collide with gas and dust from the previous nova. That’s exactly what the PTF team eventually observed.

In the months following the supernova, the PTF team watched the calcium signal drop and eventually vanish. Then, 58 days after the supernova went off, Berkeley Lab Scientist Nao Suzuki who was observing the system with the Lick telescope noticed a sudden, strong burst in calcium coming from the system, indicating that the new supernova material had finally collided with the old material.

“This was the most exciting supernova I’ve ever studied. For several months, almost every new observation showed something we’d never seen before,” says Ben Dilday, a UC Santa Barbra postdoctoral researchers and lead author of the study.

A New Kind of Type 1a Supernova

According to Dilday, it is not unusual for a star to undergo nova eruptions more than once. In fact, a “recurrent nova” system called RS Ophiuchi exists within our own Milky Way Galaxy. Located about 5,000 light years away, the system is close enough that astronomers can tell that it consists of a compact white dwarf star (the corpse of a sun-like star) orbiting a red giant. Material being blown off the red giant star in a stellar wind lands on the white dwarf. As the material builds up, the white dwarf periodically explodes, or novas, in this case, about every 20 years.

Astronomers predict that in recurring novas, the white dwarf loses more mass in the nova eruption than it gains from the red giant. Because Type 1a supernovae occur in systems where a white dwarf accretes mass from a nearby star until it can’t grow any further and explodes, many scientists concluded that recurrent nova systems could not produce Type 1a supernovae. They thought the white dwarf would lose too much mass to ever become a supernova. PTF 11kx is the first observational evidence that Type 1a supernovae can occur in these systems.

“Because we’ve looked at thousands of systems and PTF 11kx is the only one that we’ve found that looks exactly like this, we think it is probably a rare phenomenon. However, these systems could be somewhat more common, and nature is just hiding their signatures from us,” says Silverman.

The Palomar Transient Factory’s Real-Time detection pipeline is made possible with support from the DOE Office of Science, NASA, and the National Science Foundation.

Linda Vu
510-495-2402
Email :
lvu@lbl.gov


***

The Palomar Transient Factory is an international collaboration of scientists and engineers from Berkeley Lab, California Institute of Technology (Caltech), NASA’s Infrared Processing and Analysis Center, UC Berkeley, Las Cumbres Observatory Global Telescope Network, the University of Oxford, Columbia University, the Weizmann Institute of Science in Israel, and Pennsylvania State University. http://www.astro.caltech.edu/ptf/

About Berkeley Lab


Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit http://www.lbl.gov.


About NERSC


The National Energy Research Scientific Computing Center (NERSC) is the primary high-performance computing facility for scientific research sponsored by the U.S. Department of Energy’s Office of Science. Located at Lawrence Berkeley National Laboratory, the NERSC Center serves more than 4,000 scientists at national laboratories and universities conducting fundamental research in a wide range of disciplines. http://www.nersc.gov

About ESnet

The Energy Sciences Network (ESnet) provides the high-bandwidth, reliable connections that link scientists at national laboratories, universities and other research institutions, enabling them to collaborate on some of the world’s most important scientific challenges including energy, climate science, and the origins of the universe. Funded by the U.S. Department of Energy’s (DOE) Office of Science and located within the Scientific Networking Division at Lawrence Berkeley National Laboratory, ESnet provides scientists with access to unique DOE research facilities and computing resources. http://es.net

The Milky Way now has a twin (or two)

This image shows one of the two ‘exact matches’ to the Milky Way system found in the survey. The larger galaxy, denoted GAMA202627, which is similar to the Milky Way clearly has two large companions off to the bottom left of the image. In this image bluer colours indicate hotter, younger, stars like many of those that are found in our galaxy. Image Credit: Dr Aaron Robotham, ICRAR/St Andrews using GAMA data.

Research presented today at the International Astronomical Union General Assembly in Beijing has found the first group of galaxies that is just like ours, a rare sight in the local Universe.

The Milky Way is a fairly typical galaxy on its own, but when paired with its close neighbours - the Magellanic Clouds - it is very rare, and could have been one of a kind, until a survey of our local Universe found another two examples just like us.

Astronomer Dr Aaron Robotham, jointly from the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) and the University of St Andrews in Scotland, searched for groups of galaxies similar to ours in the most detailed map of the local Universe yet, the Galaxy and Mass Assembly survey (GAMA).

“We’ve never found another galaxy system like the Milky Way before, which is not surprising considering how hard they are to spot! It’s only recently become possible to do the type of analysis that lets us find similar groups,” says Dr Robotham.

“Everything had to come together at once: we needed telescopes good enough to detect not just galaxies but their faint companions, we needed to look at large sections of the sky, and most of all we needed to make sure no galaxies were missed in the survey”

Sophisticated simulations of how galaxies form don’t produce many examples similar to the Milky Way and its surrounds, predicting them to be quite a rare occurrence. Astronomers haven’t been able to tell just how rare until now, with the discovery of not just one but two exact matches amongst the hundreds of thousands of galaxies surveyed.

“We found about 3% of galaxies similar to the Milky Way have companion galaxies like the Magellanic Clouds, which is very rare indeed. In total we found 14 galaxy systems that are similar to ours, with two of those being an almost exact match,” says Dr Robotham.

The Milky Way is locked in a complex cosmic dance with its close companions the Large and Small Magellanic Clouds, which are clearly visible in the southern hemisphere night sky. Many galaxies have smaller galaxies in orbit around them, but few have two that are as large as the Magellanic Clouds.

Dr Robotham’s work also found that although companions like the Magellanic Clouds are rare, when they are found they’re usually near a galaxy very like the Milky Way, meaning we’re in just the right place at the right time to have such a great view in our night sky.

“The galaxy we live in is perfectly typical, but the nearby Magellenic Clouds are a rare, and possibly short-lived, occurrence. We should enjoy them whilst we can, they'll only be around for a few billion more years,” adds Dr Robotham.

Dr Robotham and colleagues have been awarded further time on telescopes in New South Wales and Chile to study these Milky Way twin systems now that they’ve been found.

The Galaxy and Mass Assembly (GAMA) survey is an international collaboration led from ICRAR and the Australian Astronomical Observatory to map our local Universe in closer detail.

ICRAR is a joint venture between Curtin University and The University of Western Australia providing research excellence in the field of radio astronomy.

Original Publication:
The paper “Galaxy and Mass Assembly (GAMA): In search of Milky-Way Magellanic Cloud Analogues” can be read here: http://adsabs.harvard.edu/abs/2012MNRAS.424.1448R

Further Information:

Galaxy and Mass Assembly (GAMA) – the 3D survey of our local Universe.

http://www.gama-survey.org

Contacts:

Dr Aaron Robotham
ICRAR, The University of Western Australia | University of St Andrews
Email:
aaron.robotham@icrar.org

Kirsten Gottschalk
Media Contact, ICRAR
Mobile: +61 (0) 438 361 876
Email:
kirsten.gottschalk@icrar.org


Wednesday, August 22, 2012

First Evidence Discovered of Planet's Destruction by Its Star

An artist's impression of a red supergiant engulfing a Jupiter-like planet as it expands.Credit: NASA

Credit: Marty Harris/McDonald Obs./UT-Austin
Click here for high-resolution file

The first evidence of a planet's destruction by its aging star has been discovered by an international team of astronomers. The evidence indicates that the missing planet was devoured as the star began expanding into a "red giant" — the stellar equivalent of advanced age. "A similar fate may await the inner planets in our solar system, when the Sun becomes a red giant and expands all the way out to Earth's orbit some five-billion years from now," said Alex Wolszczan, an Evan Pugh Professor of Astronomy and Astrophysics at Penn State, University, who is one of the members of the research team. Wolszczan also is the discoverer of the first planet ever found outside our solar system.

The astronomers also discovered a massive planet in a surprisingly elliptical orbit around the same red-giant star, named BD+48 740, which is older than the Sun with a radius about eleven times bigger. Wolszczan and the team's other members, Monika Adamow, Grzegorz Nowak, and Andrzej Niedzielski of Nicolaus Copernicus University in Torun, Poland; and Eva Villaver of the Universidad Autonoma de Madrid in Spain, detected evidence of the missing planet's destruction while they were using the Hobby-Eberly Telescope to study the aging star and to search for planets around it. The evidence includes the star's peculiar chemical composition, plus the highly unusual elliptical orbit of its surviving planet.

"Our detailed spectroscopic analysis reveals that this red-giant star, BD+48 740, contains an abnormally high amount of lithium, a rare element created primarily during the Big Bang 14 billion years ago," Adamow said. Lithium is easily destroyed in stars, which is why its abnormally high abundance in this older star is so unusual. "Theorists have identified only a few, very specific circumstances, other than the Big Bang, under which lithium can be created in stars," Wolszczan added. "In the case of BD+48 740, it is probable that the lithium production was triggered by a mass the size of a planet that spiraled into the star and heated it up while the star was digesting it."

The second piece of evidence discovered by the astronomers is the highly elliptical orbit of the star's newly discovered massive planet, which is at least 1.6 times as massive as Jupiter. "We discovered that this planet revolves around the star in an orbit that is only slightly wider than that of Mars at its narrowest point, but is much more extended at its farthest point," Niedzielski said. "Such orbits are uncommon in planetary systems around evolved stars and, in fact, the BD+48 740 planet's orbit is the most elliptical one detected so far." Because gravitational interactions between planets are responsible for such peculiar orbits, the astronomers suspect that the dive of the missing planet toward the star before it became a giant could have given the surviving massive planet a burst of energy, throwing it into an eccentric orbit like a boomerang.

"Catching a planet in the act of being devoured by a star is an almost improbable feat to accomplish because of the comparative swiftness of the process, but the occurrence of such a collision can be deduced from the way it affects the stellar chemistry," Villaver explained. "The highly elongated orbit of the massive planet we discovered around this lithium-polluted red-giant star is exactly the kind of evidence that would point to the star's recent destruction of its now-missing planet."

The paper describing this discovery is posted in an early online edition of the Astrophysical Journal Letters (Adamow et al. 2012, ApJ, 754, L15). The Hobby-Eberly Telescope is a joint project of the University of Texas at Austin, Penn State University, Ludwig-Maximilians-Universitat Munchen, and Georg-August-Universitat Gottingen. The telescope is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

[ Barbara K. Kennedy ]

CONTACTS

Alexander Wolszczan:
alex@astro.psu.edu, +1 814-863-1756
Andrzej Niedzielski:
Andrzej.Niedzielski@astri.umk.pl, +56 611-30-57
Eva Villaver: Eva.Villaver@uam.es, +34 914976797
Barbara Kennedy (Penn State PIO): +1 814-863-4682,
science@psu.edu

FINANCIAL SUPPORT

This research received financial support from the U. S. National Aeronautics and Space Administration (NASA grant NNX09AB36G), the Polish Ministry of Science and Higher Education (grant N N203 510938), the Spanish Ministry of Science and Innovation (grant AYA2010-20630), and the Marie Curie Seventh Framework Programme (FP7-People-RG268111).

Friday, August 17, 2012

A Lonely Galactic Island

DDO 190, UGC 9240
Credit: ESA/Hubble & NASA

Fullsize Original 29.1 MB
Large JPEG 8.1 MB
Screensize JPEG 559.6 KB

In terms of intergalactic real estate, our Solar System has a plumb location as part of a big, spiral galaxy, the Milky Way. Numerous, less glamorous dwarf galaxies, keep
the Milky Way company. Many galaxies, however, are comparatively isolated, without close neighbours. One such example is the small galaxy known as DDO 190, snapped here in a new image from the NASA/ESA Hubble Space Telescope.

DDO 190 is classified as a dwarf irregular galaxy as it is relatively small and lacks clear structure. Older, reddish stars mostly populate DDO 190’s outskirts, while some younger, bluish stars gleam in DDO 190’s more crowded interior. Some pockets of ionised gas heated up by stars appear here and there, with the most noticeable one shining towards the bottom of DDO 190 in this picture. Meanwhile, a great number of distant galaxies with evident spiral, elliptical and less-defined shapes glow in the background.

DDO 190 lies around nine million light-years away from our Solar System. It is considered part of the loosely associated Messier 94 group of galaxies, not far from the Local Group of galaxies that includes the Milky Way. Canadian astronomer Sidney van der Bergh was the first to record DDO 190 in 1959 as part of the DDO catalogue of dwarf galaxies. (“DDO” stands for the David Dunlap Observatory, now managed by the Royal Astronomical Society of Canada, where the catalogue was created).

Although within the Messier 94 group, DDO 190 is on its own. The galaxy’s nearest dwarf galaxy neighbour, DDO 187, is thought to be no closer than three million light-years away. In contrast, many of the Milky Way’s companion galaxies, such as the Large and Small Magellanic Clouds, reside within a fifth or so of that distance, and even the giant spiral of the Andromeda Galaxy is closer to the Milky Way than DDO 190 is to its nearest neighbour.

Hubble’s Advanced Camera for Surveys captured this image in visible and infrared light. The field of view is around 3.3 by 3.3 arcminutes

A version of this image was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant Claude Cornen. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed and the results will be published soon.

Source: ESA/Hubble - Space Telescope

Thursday, August 16, 2012

Hubble Watches Star Clusters on a Collision Course


30 Doradus, 30 Dor, Tarantula Nebula
Acknowledgment: R. O'Connell (University of Virginia)
and the Wide Field Camera 3 Science Oversight Committee

Image Credit: NASA, ESA, and E. Sabbi (ESA/STScI)

Astronomers using data from NASA's Hubble Space Telescope have caught two clusters full of massive stars that may be in the early stages of merging. The clusters are 170,000 light-years away in the Large Magellanic Cloud, a small satellite galaxy to our Milky Way.

What at first was thought to be only one cluster in the core of the massive star-forming region 30 Doradus (also known as the Tarantula Nebula) has been found to be a composite of two clusters that differ in age by about one million years.

The entire 30 Doradus complex has been an active star-forming region for 25 million years, and it is currently unknown how much longer this region can continue creating new stars. Smaller systems that merge into larger ones could help to explain the origin of some of the largest known star clusters.

Lead scientist Elena Sabbi of the Space Telescope Science Institute in Baltimore, Md., and her team began looking at the area while searching for runaway stars, fast-moving stars that have been kicked out of their stellar nurseries where they first formed. "Stars are supposed to form in clusters, but there are many young stars outside 30 Doradus that could not have formed where they are; they may have been ejected at very high velocity from 30 Doradus itself," Sabbi said.

She then noticed something unusual about the cluster when looking at the distribution of the low-mass stars detected by Hubble. It is not spherical, as was expected, but has features somewhat similar to the shape of two merging galaxies where their shapes are elongated by the tidal pull of gravity. Hubble's circumstantial evidence for the impending merger comes from seeing an elongated structure in one of the clusters, and from measuring a different age between the two clusters.

According to some models, the giant gas clouds out of which star clusters form may fragment into smaller pieces. Once these small pieces precipitate stars, they might then interact and merge to become a bigger system. This interaction is what Sabbi and her team think they are observing in 30 Doradus.

Also, there is an unusually large number of high-velocity stars around 30 Doradus. Astronomers believe that these stars, often called "runaway stars" were expelled from the core of 30 Doradus as the result of dynamical interactions. These interactions are very common during a process called core collapse, in which more-massive stars sink to the center of a cluster by dynamical interactions with lower-mass stars. When many massive stars have reached the core, the core becomes unstable and these massive stars start ejecting each other from the cluster.

The big cluster R136 in the center of the 30 Doradus region is too young to have already experienced a core collapse. However, since in smaller systems the core collapse is much faster, the large number of runaway stars that has been found in the 30 Doradus region can be better explained if a small cluster has merged into R136.

Follow-up studies will look at the area in more detail and on a larger scale to see if any more clusters might be interacting with the ones observed. In particular the infrared sensitivity of NASA's planned James Webb Space Telescope (JWST) will allow astronomers to look deep into the regions of the Tarantula Nebula that are obscured in visible-light photographs. In these areas cooler and dimmer stars are hidden from view inside cocoons of dust. Webb will better reveal the underlying population of stars in the nebula.

The 30 Doradus Nebula is particularly interesting to astronomers because it is a good example of how star-forming regions in the young universe may have looked. This discovery could help scientists understand the details of cluster formation and how stars formed in the early universe.

The members of Sabbi's team are D.J. Lennon (ESA/STScI), M. Gieles (University of Cambridge, UK), S.E. de Mink (STScI/JHU), N.R. Walborn, J. Anderson, A. Bellini, N. Panagia, and R. van der Marel (STScI), and J. Maíz Appelániz (Instituto de Astrofísica de Andalucía, CISC, Spain)

CONTACT

Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514

villard@stsci.edu

Elena Sabbi
Space Telescope Science Institute, Baltimore, Md.
410-338-4732

sabbi@stsci.edu