Friday, June 26, 2009

Dating young star clusters in starburst galaxy M82

Figure 1: Existing dataset of star cluster spectroscopy (16 hours of GMOS on-target integration time in all), with slit positions plotted over HST-ACS imaging of M82 (Hubble Heritage ACS mosaic of 6 WFC images, Mutchler et al. 2007). The dataset samples individual star clusters across the entire galaxy disk and cluster associations in the nucleus.

Figure 2: Cluster age dating. Each of these three image-spectrum pairs represents a BVI composite image and part of its optical spectrum. The spatial scale of the images is a square of side 175 pc. In the spectra, the top panel shows the age fit, with the solid line and dashed lines representing the observed spectrum and best fitting model respectively. The dashed blue boxes indicate the spectral regions where the fit takes place. The bottom panel shows the probability distribution of the fit across age-space, with a vertical line indicating the best fitting age and a horizontal line to delimit a confidence region.

Figure 3: A ground- and space-based HST/WIYN composite image of M82 and its optically bright superwind. This has been colour-coded to show its supergalactic wind running left-right (north-south) and a nearly vertical disk of stars. Broad blue, green and red filters were used to render the relatively smooth stellar disk. Purple represents emission from hydrogen.
Credit: Mark Westmoquette (UCL), Jay Gallagher (Wisconsin-Madison), Linda Smith (STScI/UCL)

Aimed at deciphering the secrets of archetypal starburst galaxy M82, the Gemini Multi-Object Spectrograph (GMOS) on Gemini North was employed by a team of UK- and US-based astronomers, led by Iraklis Konstantopoulos of University College London (UCL). The astronomers assembled key data for the largest sample of young extragalactic star clusters to date. M82 presents a gas, dust and stellar system that has intrigued scientists for decades due to its irregular, dusty appearance and extravagant super-galactic wind (see Figure 1).

Konstantopoulos et al. used the Gemini spectra to derive the age of 49 clusters in the disk, nucleus and halo of the galaxy (Figure 2). The resulting demographics were used to investigate the starburst history of M82, thus demonstrating the usefulness of star clusters as probes of star formation in environments where stars are too faint to be observed. On this basis, the observations were compared to theoretical models of starburst evolution in M82 (Förster Schreiber et al., 2003) and simulations that studied the interaction between M82 and its massive neighbour, M81, and the consequent burst of star formation (Yun et al., 1999).

In addition to deriving clusters ages, the group were able to establish a clear picture of this dusty, edge-on galaxy by combining radial velocity information with optical and near-IR imaging from the HST as well as CO observations from the Owens Valley Radio Observatory millimeter interferometer (Walter, Weiss & Scoville, 2002).

The combination and interpretation of the multi-wavelength data-set shows that the galaxy is far simpler than had previously been thought: it has a regular, two-armed spiral structure that is obscured in a highly irregular fashion by gas and dust perturbedby the recent interaction of the last ~220 million years. This is exemplified by the finding that the bright region 'B' (comparable to the nucleus in terms of apparent luminosity) is no more than an “artefact”: a hole in the dust distribution.

For more details, see the full article “A spectroscopic census of the M82 stellar cluster population”, by Iraklis S. Konstantopoulos, Nate Bastian, Linda J. Smith, Mark S. Westmoquette, Gelys Trancho and Jay S. Gallagher, The Astrophysical Journal, 2009, in press [or astro-ph/0906.2006].

The content of the article represents a large part of Konstantopoulos (UCL) PhD thesis. This work falls under two large Gemini projects: one is an investigation of M82 (led by Linda Smith) with respect to its star cluster content (presented here), the interstellar medium and super-galactic wind of M82 (led by Mark Westmoquette, University College London). The other, headed by Gelys Trancho (Gemini Observatory), is focussed on the study of star cluster formation in interacting and merging galaxies.

Thursday, June 25, 2009

Milky Way's super-efficient particle accelerators caught in the act

The rim of RCW 86

Image of part of a stellar remnant whose explosion was recorded in 185 AD. By studying this remnant in detail, a team of astronomers was able to solve the mystery of the Milky Way’s super-efficient particle accelerators. The team shows that the shock wave visible in this area is very efficient at accelerating particles and the energy used in this process matches the number of cosmic rays observed on Earth. North is toward the top right and east to the top left. The image is about 6 arc minutes across.

DSS + insert, annotated

This wide-field image contains the area where a team of researchers confirmed that cosmic rays from our galaxy are very efficiently accelerated in the remnants of exploded stars. The red line guides the eye to various regions where the remnants of the stellar explosion are most visible. The boxed area contains an insert of data from the VLT and Chandra. This region, named RCW 86, is centered on the position where a star exploded in 185 AD. The field of view is 4 degrees across with north to the top and east to the left.
DSS image

A wide-field image of the area of the sky where the mystery of the Milky Way’s super-efficient particle accelerators was solved by studying the ancient RCW 86 supernova remnant.

This image in full resolution (TIF format, 649 MB) is available on this link.

ESO PR Video 23a/09
Zoom-in RCW 86

Thanks to a unique "ballistic study" that combines data from ESO's Very Large Telescope and NASA's Chandra X-ray Observatory, astronomers have now solved a long-standing mystery of the Milky Way’s particle accelerators. They show in a paper published today on Science Express that cosmic rays from our galaxy are very efficiently accelerated in the remnants of exploded stars.

During the Apollo flights astronauts reported seeing odd flashes of light, visible even with their eyes closed. We have since learnt that the cause was cosmic rays — extremely energetic particles from outside the Solar System arriving at the Earth, and constantly bombarding its atmosphere. Once they reach Earth, they still have sufficient energy to cause glitches in electronic components.

Galactic cosmic rays come from sources inside our home galaxy, the Milky Way, and consist mostly of protons moving at close to the speed of light, the “ultimate speed limit” in the Universe. These protons have been accelerated to energies exceeding by far the energies that even CERN’s Large Hadron Collider will be able to achieve.

“It has long been thought that the super-accelerators that produce these cosmic rays in the Milky Way are the expanding envelopes created by exploded stars, but our observations reveal the smoking gun that proves it”, says Eveline Helder from the Astronomical Institute Utrecht of Utrecht University in the Netherlands, the first author of the new study.

“You could even say that we have now confirmed the calibre of the gun used to accelerate cosmic rays to their tremendous energies”, adds collaborator Jacco Vink, also from the Astronomical Institute Utrecht.

For the first time Helder, Vink and colleagues have come up with a measurement that solves the long-standing astronomical quandary of whether or not stellar explosions produce enough accelerated particles to explain the number of cosmic rays that hit the Earth’s atmosphere. The team’s study indicates that they indeed do and it directly tells us how much energy is removed from the shocked gas in the stellar explosion and used to accelerate particles.

“When a star explodes in what we call a supernova a large part of the explosion energy is used for accelerating some particles up to extremely high energies”, says Helder. “The energy that is used for particle acceleration is at the expense of heating the gas, which is therefore much colder than theory predicts”.

The researchers looked at the remnant of a star that exploded in AD 185, as recorded by Chinese astronomers. The remnant, called RCW 86, is located about 8200 light-years away towards the constellation of Circinus (the Drawing Compass). It is probably the oldest record of the explosion of a star.

Using ESO’s Very Large Telescope, the team measured the temperature of the gas right behind the shock wave created by the stellar explosion. They measured the speed of the shock wave as well, using images taken with NASA’s X-ray Observatory Chandra three years apart. They found it to be moving at between 10 and 30 million km/h, between 1 and 3 percent the speed of light.

The temperature of the gas turned out to be 30 million degrees Celsius. This is quite hot compared to everyday standards, but much lower than expected, given the measured shock wave’s velocity. This should have heated the gas up to at least half a billion degrees.

“The missing energy is what drives the cosmic rays”, concludes Vink.

More Information
This research was presented in a paper to appear in Science: Measuring the cosmic ray acceleration efficiency of a supernova remnant, by E. A. Helder et al.

The team is composed of E.A. Helder, J. Vink and F. Verbunt (Astronomical Institute Utrecht, Utrecht University, The Netherlands), C.G. Bassa and J.A.M. Bleeker (SRON, Netherlands Institute for Space Research, The Netherlands), A. Bamba (ISAS/JAXA Department of High Energy Astrophysics, Kanagawa, Japan), S. Funk (Kavli Institute for Particle Astrophysics and Cosmology, Stanford, USA), P. Ghavamian (Space Telescope Science Institute, Baltimore, USA), K. J. van der Heyden (University of Cape Town, South Africa), and R. Yamazaki (Department of Physical Science, Hiroshima University, Japan). C.G. Bassa is also affiliated with the Radboud University Nijmegen, the Netherlands.

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, 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. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

To request the Science paper:

Eveline Helder, Jacco Vink
Astronomical Institute Utrecht
The Netherlands
Phone: +31 30 253 5221, +31 30 253 2513

Stefan Funk
Kavli Institute for Particle Astrophysics and Cosmology, Stanford, USA
Phone: +1 650 926 8979

Ryo Yamazaki
Hiroshima University, Japan
Phone: +81-82-424-7362

Aya Bamba
ISAS/JAXA Department of High Energy Astrophysics
Kanagawa, Japan
Phone: +81-42-759-8138
E-mail :

ESO La Silla - Paranal - ELT Press Officer:
Dr. Henri Boffin - +49 89 3200 6222 -

ESO Press Officer in Chile:
Valeria Foncea - +56 2 463 3123 -

National contacts for the media:

STScI Joins the Search for Other Earths in Space

Credit: NASA

The Space Telescope Science Institute (STScI) in Baltimore, Md., is partnering on a historic search for Earth-size planets around other stars. STScI is the data archive center for NASA's Kepler mission, a spacecraft that is undertaking a survey for Earth-size planets in our region of the galaxy. The spacecraft sent its first raw science data to STScI on June 19.

The Institute was the logical choice for storing the anticipated flood of data because its scientists have processed enough observations from NASA's Hubble Space Telescope over the past 19 years to fill almost two collections of material in the U.S. Library of Congress.

The Institute's role is to convert the raw science data into files that can be analyzed by Kepler researchers and to store the files every three months in an archive.

"We are part of this mission because of our experience with Hubble data processing and archiving," explained David Taylor, project manager for the development of Kepler's Data Management Center at the Institute. "NASA's Ames Research Center [the home of Kepler's science operations] had not done a science mission like this one. Building the Data Management Center from scratch would have been more costly, and it would have taken longer to get up to speed."

Launched on March 6 on a Delta II rocket from Cape Canaveral, Fla., the Kepler spacecraft will spend the next 3 1/2 years searching for habitable planets by staring nonstop at more than 100,000 Sun-like stars out of about 4.5 million catalogued stars in the spacecraft's field-of-view, located in the summer constellations Cygnus and Lyra.

The spacecraft simultaneously measures the variations in brightness of the more than 100,000 stars every 30 minutes, searching for periodic dips in a star's brightness that happen when an orbiting planet crosses in front of it and partially blocks the light. These fluctuations are tiny compared with the brightness of the star. For an Earth-size planet transiting a solar-type star, the change in brightness is less than 1/100 of 1 percent. This event is similar to the dimming one might see if a flea were to crawl across a car's headlight viewed from several miles away.

When the mission is completed in several years, the survey should tell astronomers how common Earth-size planets are around stars.

Once a month, the Kepler spacecraft will send its science data, about 50 gigabytes, back to Kepler's Mission Operations Center at the Laboratory for Atmospheric and Space Physics at the University of Colorado. Raw science data will then be relayed to the Institute's Data Management Center (DMC). DMC Operations will convert the information into Flexible Image Transport System (FITS) files, a digital file format used to store, transmit, and manipulate scientific information. FITS is the most commonly used digital file format in astronomy.

The FITS files will be sent to the Kepler Scientific Operations Center (SOC) at Ames Research Center in California, where the science data analysis will be carried out.

Kepler mission scientists will turn the data into 30-minute snapshots of light from each of the 100,000 or more stars. From these snapshots, the scientists will construct a light curve for each star, which details any brightness fluctuations. They will review the light curves to look for any periodic decrease in brightness, an indication of a possible transiting planet.

The mission scientists also will use the light curves to study the stars and their interiors. Because of the quality of the Kepler data and the large number of stars the spacecraft will observe, scientists hope to improve their understanding of stellar evolution.

"The mission's main purpose is to find planets that are the same distance from its solar-type star as Earth is from the Sun," said Daryl Swade, who directed the systems engineering development of Kepler's Data Management Center at the Institute. "So that means that the planet would cross in front of its star every year. We would need three or four of these transits to confirm the detection, which will take about three or four years."

A planet at an Earth-like distance from its star would be in the star's "habitable zone," where temperatures are just right for liquid oceans to exist on the surface without freezing over or evaporating away. On Earth, a liquid ocean was needed to nurture the chemical processes that lead to the appearance of life. This is considered an important prerequisite for life as we know it to appear elsewhere in the galaxy.

Kepler's science data also will be archived at the Institute. Every three months the SOC at Ames will ship FITS files in a 500-gigabyte computer hard drive to the Institute for storage in the Multimission Archive, or MAST. The archive houses data from about 14 missions, including Hubble, the Far Ultraviolet Spectroscopic Explorer (FUSE), and the Galaxy Evolution Explorer (GALEX).

Based on its strong track record in processing and archiving data, the Institute could earn a role in many future missions.

"Partnering with other institutions to share the duties of a mission may be a trend for future missions," Taylor said.

The Space Telescope Science Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, D.C.

Kepler is a NASA Discovery mission. NASA Ames Research Center, Moffett Field, Calif., is the home organization of the science principal investigator and is responsible for the ground system development, mission operations, and science data analysis. NASA Jet Propulsion Laboratory, Pasadena, Calif., managed the Kepler mission development. Ball Aerospace & Technologies Corp. of Boulder, Colo., was responsible for developing the Kepler flight system and is supporting mission operations.

Donna Weaver
Space Telescope Science Institute, Baltimore, Md.

Wednesday, June 24, 2009

Lyman Alpha Blobs: Galaxies Coming of Age in Cosmic Blobs

bCredit: Left panel: X-ray (NASA/CXC/Durham Univ./D.Alexander et al.); Optical (NASA/ESA/STScI/IoA/S.Chapman et al.); Lyman-alpha Optical (NAOJ/Subaru/Tohoku Univ./T.Hayashino et al.); Infrared (NASA/JPL-Caltech/Durham Univ./J.Geach et al.); Right, Illustration: NASA/CXC/M.Weiss

A deep study of 29 gigantic blobs of hydrogen gas has been carried out with NASA's Chandra X-ray Observatory to identify the source of immense energy required to illuminate these structures. These mysterious blobs - called "Lyman-alpha blobs" by astronomers because of the light they emit - are several hundred thousand light years across and are seen when the Universe is only about two billion years old, or about 15% of its current age.

The composite image on the left shows one of the largest blobs observed in this study. Glowing hydrogen gas in the blob is shown by a Lyman-alpha optical image (colored yellow) from the National Astronomy Observatory of Japan's Subaru telescope. A galaxy located in the blob is visible in a broadband optical image (white) from the Hubble Space Telescope and an infrared image from the Spitzer Space Telescope (red). Finally, the Chandra X-ray Observatory image in blue shows evidence for a growing supermassive black hole in the center of the galaxy. Radiation and outflows from this active black hole are powerful enough to light up and heat the gas in the blob. Radiation and winds from rapid star formation occurring in the galaxy is believed to have similar effects. Clear evidence for four other active black holes in blobs is also seen.

The artist's representation on the right shows what one of the galaxies inside a blob might look like if viewed at a relatively close distance. A two-sided outflow powered by the supermassive black hole buried inside the middle of the galaxy is shown in bright yellow, above and below the spiral arms of the galaxy. This outflow illuminates and heats gas surrounding the galaxy. Radiation from regions close to the black hole will also play a significant role in lighting up and heating the blob. Stars are forming at a rapid rate in this galaxy, and young stars are being destroyed in supernova explosions. The three bright stars above the central bulge of the galaxy are examples of such supernovas (a companion illustration shows the effects of such explosions).

These new results show how blobs fit into the cosmic story of how galaxies and black holes evolve. Galaxies are believed to form when gas flows inwards under the pull of gravity and cools by emitting radiation. This process should stop when the gas is heated by radiation and outflows from galaxies and their black holes. Blobs could be a sign of this first stage, or of the second.

Based on the new data and theoretical arguments, Geach and his colleagues show that heating of gas by growing supermassive black holes and bursts of star formation, rather than cooling of gas, most likely powers the blobs. The implication is that blobs represent a stage when the galaxies and black holes are just starting to switch off their rapid growth because of these heating processes. This is a crucial stage of the evolution of galaxies and black holes -- known as "feedback" -- and one that astronomers have long been trying to understand.

Fast Facts for Lyman Alpha Blobs:

Scale: Left panel is 38 arcsec across
Category: Cosmology/Deep Fields/X-ray Background
Coordinates: (J2000) RA 22h 17m 39s | Dec +00° 13' 27.5
Constellation: Aquarius
Observation Date: 08/01/2007 - 12/30/2007
Observation Time: 4 days15 hours
Obs. ID: 8034-8036, 9717
Color Code: X-ray (Blue); Optical (White, Yellow); Infrared (Red)
Instrument: ACIS
References: J. Geach et al. 2009, ApJ, in press
Distance Estimate: About 11.5 billion light years

Friday, June 19, 2009

KAGUYA (SELENE) Last shots captured by the HDTV

The Japan Aerospace Exploration Agency (JAXA) and the Japan Broadcasting Corporation (NHK) would like to release the final still images taken by the onboard High Definition Television (HDTV) of the lunar explorer "KAGUYA" just prior to its maneuvered falling to the Moon. The images are attached below. The KAGUYA was launched on September 14, 2007, and was controlled to be dropped to the Moon on June 11, 2009, as its mission was completed.

The series of continued shots was taken with an interval of about one minute by the HDTV (Teltephoto) while the KAGUYA was maneuvered to decrease its altitude toward the impact position (around GILL crater.)

We can see the approaching Moon surface as the KAGUYA went closer to it. After the final image, the KAGUYA moved into the shaded area to make its final landing, thus it was pitch dark while taking an image. This is the very final image shooting of the Moon by the KAGUYA HDTV.

You can enjoy images taken by the KAGUYA HDTV through JAXA Digital Archives, the KAGUYA Image Gallery, and the JAXA channel on YouTube.

[JAXA Website Digital Archives]
(Search by selecting the following: Subject: Observation Images, Category: Moon and Planet Exploration, Mission: Moon)

[JAXA KAGUYA Image Gallery]

[YouTube JAXA Channel]

[NHK : Kaguya Archives]

Around Drygalski P (Diameter: about 30 km) At 3:14 a.m. on June 11, 2009 (JST) (Altitude at 20.7 km) The last clear still image taken by the KAGUYA's HDTV (Teltephoto) when it went into the shaded area from the sunshine area. You can clearly see the rough surface inside the crater as the sun shone from the back left hand side in the polar area.

An arrow shows the location of sequential photo shooting by the HDTV

Sunspots Revealed in Striking Detail by Supercomputers

The interface between a sunspot's umbra (dark center) and penumbra (lighter outer region) shows a complex structure with narrow, almost horizontal (lighter to white) filaments embedded in a background having a more vertical (darker to black) magnetic field. Farther out, extended patches of horizontal field dominate. For the first time, NCAR scientists and colleagues have modeled this complex structure in a comprehensive 3D computer simulation, giving scientists their first glimpse below the visible surface to understand the underlying physical processes. [Enlarge] (©UCAR, image courtesy Matthias Rempel, NCAR. News media terms of use*)
See more images and video animations in the
Sunspots Multimedia Gallery

BOULDER—In a breakthrough that will help scientists unlock mysteries of the Sun and its impacts on Earth, an international team of scientists led by the National Center for Atmospheric Research (NCAR) has created the first-ever comprehensive computer model of sunspots. The resulting visuals capture both scientific detail and remarkable beauty.

The high-resolution simulations of sunspot pairs open the way for researchers to learn more about the vast mysterious dark patches on the Sun's surface. Sunspots are the most striking manifestations of solar magnetism on the solar surface, and they are associated with massive ejections of charged plasma that can cause geomagnetic storms and disrupt communications and navigational systems. They also contribute to variations in overall solar output, which can affect weather on Earth and exert a subtle influence on climate patterns.

The research, by scientists at NCAR and the Max Planck Institute for Solar System Research (MPS) in Germany, is being published this week in Science Express.

"This is the first time we have a model of an entire sunspot," says lead author Matthias Rempel, a scientist at NCAR's High Altitude Observatory. "If you want to understand all the drivers of Earth's atmospheric system, you have to understand how sunspots emerge and evolve. Our simulations will advance research into the inner workings of the Sun as well as connections between solar output and Earth's atmosphere."

Ever since outward flows from the center of sunspots were discovered 100 years ago, scientists have worked toward explaining the complex structure of sunspots, whose number peaks and wanes during the 11-year solar cycle. Sunspots encompass intense magnetic activity that is associated with solar flares and massive ejections of plasma that can buffet Earth's atmosphere. The resulting damage to power grids, satellites, and other sensitive technological systems takes an economic toll on a rising number of industries.

Creating such detailed simulations would not have been possible even as recently as a few years ago, before the latest generation of supercomputers and a growing array of instruments to observe the Sun. Partly because of such new technology, scientists have made advances in solving the equations that describe the physics of solar processes.

The work was supported by the National Science Foundation, NCAR's sponsor. The research team improved a computer model, developed at MPS, that built upon numerical codes for magnetized fluids that had been created at the University of Chicago.

Computer model provides a unified physical explanation

The new computer models capture pairs of sunspots with opposite polarity. In striking detail, they reveal the dark central region, or umbra, with brighter umbral dots, as well as webs of elongated narrow filaments with flows of mass streaming away from the spots in the outer penumbral regions. They also capture the convective flow and movement of energy that underlie the sunspots, and that are not directly detectable by instruments.

The models suggest that the magnetic fields within sunspots need to be inclined in certain directions in order to create such complex structures. The authors conclude that there is a unified physical explanation for the structure of sunspots in umbra and penumbra that is the consequence of convection in a magnetic field with varying properties.

The simulations can help scientists decipher the mysterious, subsurface forces in the Sun that cause sunspots. Such work may lead to an improved understanding of variations in solar output and their impacts on Earth.

Supercomputing at 76 trillion calculations per second

To create the model, the research team designed a virtual, three-dimensional domain that simulates an area on the Sun measuring about 31,000 miles by 62,000 miles and about 3,700 miles in depth - an expanse as long as eight times Earth's diameter and as deep as Earth's radius. The scientists then used a series of equations involving fundamental physical laws of energy transfer, fluid dynamics, magnetic induction and feedback, and other phenomena to simulate sunspot dynamics at 1.8 billion points within the virtual expanse, each spaced about 10 to 20 miles apart. For weeks, they solved the equations on NCAR's new bluefire supercomputer, an IBM machine that can perform 76 trillion calculations per second.

The work drew on increasingly detailed observations from a network of ground- and space-based instruments to verify that the model captured sunspots realistically.

The new models are far more detailed and realistic than previous simulations that failed to capture the complexities of the outer penumbral region. The researchers noted, however, that even their new model does not accurately capture the lengths of the filaments in parts of the penumbra. They can refine the model by placing the grid points even closer together, but that would require more computing power than is currently available.

"Advances in supercomputing power are enabling us to close in on some of the most fundamental processes of the Sun," says Michael Knölker, director of NCAR's High Altitude Observatory and a co-author of the paper. "With this breakthrough simulation, an overall comprehensive physical picture is emerging for everything that observers have associated with the appearance, formation, dynamics, and the decay of sunspots on the Sun's surface."

First view of what goes on below the surface of sunspots. Lighter/brighter colors indicate stronger magnetic field strength in this subsurface cross section of two sunspots. For the first time, NCAR scientists and colleagues have modeled this complex structure in a comprehensive 3D computer simulation, giving scientists their first glimpse below the visible surface to understand the underlying physical processes. This image has been cropped horizontally for display. [Enlarge & Display Full Image] (©UCAR, image courtesy Matthias Rempel, NCAR. News media terms of use*)
See a video animation of this and other sunspot visualizations as well as still "photo" images in the Sunspots Multimedia Gallery.

News media reproduction to illustrate this story and nonprofit use permitted with proper attribution as provided above and acceptance of UCAR's terms of use. Find more images in the UCAR Digital Image Library.

The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Herschels first picture of an object in space

The famous 'Whirlpool Galaxy' was first observed by Charles Messier in 1773 and he designated it Messier 51 (M51). This spiral galaxy lies relatively nearby, about 35 million light-years away, in the constellation of Canes Venatici. M51 was the first galaxy discovered with a spiral structure.

The image is a composite of three observations taken at wavelengths of 70, 100 and 160 micrometres and was taken by the Herschel PACS (Photodetector Array Camera and Spectrometer) instrument, on 14 and 15 June, immediately after the spacecraft’s cryocover was opened. C
redit: ESA.

Comparison of M51 imaged with the Spitzer Space Telescope (left panel) and an image of the same galaxy taken with the Herschel Space Observatory (right panel), launched just a month ago.

The obvious advantage of the larger size of the telescope is clearly reflected in the much higher resolution of the image: Herschel reveals structures that cannot be discerned in the Spitzer image. Both images were taken at the wavelength of 160 microns.
Credits: Left panel: NASA/JPL-Caltech/SINGS, Right panel: ESA and the PACS Consortium.

Far-infrared image of M 51, the 'whirlpool galaxy' at three different wavelengths (160, 100 and 70 microns) , taken by the Herschel Photoconductor Array Camera and Spectrometer, PACS. These images clearly demonstrate that the shorter the wavelength, the sharper the image — this is a very important message about the quality of Herschel’s optics, since PACS observes at Herschel’s shortest wavelengths. Credits: ESA/PACS Consortium.

The European space telescope Herschel captured its first image of an object in the Universe. Scientists are talking about the comparatively high quality of the picture taken by Herschel's PACS instrument. The image shows the galaxy M51, known as the 'Whirlpool Galaxy'. Although at this early stage all the settings of the telescope are not fully calibrated, its performance already exceeds expectations.

The famous 'Whirlpool Galaxy' was first observed by Charles Messier in 1773 and he designated it Messier 51 (M51). This spiral galaxy lies relatively nearby, about 35 million light-years away, in the constellation of Canes Venatici. M51 was the first galaxy discovered with a spiral structure.

The image is a composite of three observations taken at 70, 100 and 160 microns, and was taken by PACS on 14 and 15 June, immediately after the spacecraft's cryocover was opened.

Herschel was carried into space on 14 May 2009, together with the Planck satellite – which will examine the cosmic microwave background radiation – by an Ariane 5 ECA launch vehicle. The German contribution to Herschel was financed by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) using funds from the Germany Ministry of Economics and Technology (Bundesministerium für Wirtschaft und Technologie; BMWi).

German scientists and engineers are significantly involved in this European Space Agency (ESA) mission. The instrument that produced the first image, the Photodetector Array Camera and Spectrometer (PACS) was developed under the direction of the Max Planck Institute for Extraterrestrial Physics (Max-Planck-Institut für extraterrestrische Physik; MPE).

During the last few weeks, while Herschel was making its 1.5-million kilometre journey to its target orbit around the second Lagrange point (L2) of the Sun-Earth system, all the spacecraft systems were being tested. Everything worked perfectly, in accordance with a detailed plan.

The first truly critical milestone was passed at 12:53 CEST (10:53 UTC) on 14 June, when the pyrotechnic bolts holding down the vacuum-tight cover on Herschel’s cryostat fired and the cover opened. Known as the cryocover, this 'lens cap' had closed the container of liquid helium that houses the coldest parts of the spacecraft’s instruments, protecting them during ground handling, launch and the early part of the journey to L2. Once the cryocover was open, the instruments could 'see' into space for the first time.

Herschel is the first space observatory that covers the complete spectrum of wavelengths from the far infrared to the sub-millimetre band (60 – 670 micrometres). Herschel will examine parts of this spectrum for the first time. This is the reason why astronomers expect an abundance of new discoveries. Scientists will examine the development and evolution of galaxies since close to the beginning of the universe. Herschel will also contribute to our understanding of comets and investigate planetary atmospheres and surfaces in our Solar System.

To undertake these tasks, Herschel carries three scientific instruments:
  • an imaging photometer and integral field line spectrometer – PACS (Photodetector Array Camera and Spectrometer)
  • a high-resolution heterodyne spectrometer – HIFI (Heterodyne instrument for the Far Infrared) and the imaging photometer and
  • an imaging Fourier transform spectrometer – SPIRE (Spectral and Photometric Imaging Receiver)
The main mirror of the telescope has a diameter of 3.5 metres. Herschel is therefore the largest space telescope ever, with a mirror diameter about one-and-a-half times larger than Hubble. To save weight, which is relevant for the launch, the mirror is made out of the ceramic material silicon carbide – used for the first time in a mirror of this size.

Herschel will remain in operation for about three years. The duration of the mission is determined primarily by the availability of liquid helium for instrument cooling and the fuel needed for the thrusters that control the spacecraft's attitude and orbit. Because the Ariane 5 ECA launch vehicle delivered Herschel and Planck very accurately into their transfer orbits, Herschel used less fuel for trajectory corrections than expected.

With the capture of this first image, Herschel has begun its work. As the mission progresses, the scientists expect to gain an enormous amount of new and important knowledge about cosmology, the Big Bang and the origin and the structure of the universe.


Michael Müller
Deutsches Zentrum für Luft- und Raumfahrt (DLR) - German Aerospace Center
Communication Department
Tel.: +49 228 447-385
Fax: +49 228 447-386

Dr.-Ing. Christian Gritzner
German Aerospace Center
Space Agency, Space Science
Tel.: +49 228 447-530
Fax: +49 228 447-706


Deutsches Zentrum für Luft- und Raumfahrt (DLR) - German Aerospace Center

Thursday, June 18, 2009

Planet found in tilted orbit around distant star

Joshua Winn explains the method used to detect the planet XO-3b's tilted orbit. Because of its rotation, light from one side of the star is blue-shifted (moving toward the observer), while the other side is redshifted (moving away). When a planet crosses it on a tilted orbit, it blocks out one side more than the other, changing the balance of colors in the star's light. Photo / Donna Coveney

XO-3b's eccentric orbit.
Credit: New Scientist

A collision between planets, like the one illustrated,
could have caused the odd orbit of XO-3b
Illustration: NASA/JPL-Caltech

Odd discovery may help refine theories about how planets, solar systems form

An international team of researchers has found a planet around another star whose orbit is steeply tilted from the plane of the star's equator, a finding that contradicts some theories about how solar systems form.

In our own solar system, all of the planets orbit the sun almost exactly in the same plane as the sun's rotation - and that alignment is required by currently accepted theories of how stars and planets form from a collapsing disk of dust and gas. Any misalignment, such as the one the team found, must have occurred as a result of a disturbance sometime after the planet's formation, theorists say.

Astronomers are interested in exploring the characteristics of such distant planets partly to help refine theories of planet formation, and partly just to understand the kinds of variations that may be possible in the universe around us - to "see how the dice get rolled in other solar systems," says MIT physicist Joshua Winn, who led the team that measured the planet's tilted orbit.

Detecting this oddball orbit required a combination of good luck, advanced technology and ingenious methodology. Winn, assistant professor of physics in MIT's Kavli Institute for Astrophysics and Space Research, and a team of astronomers used one of the world's two largest telescopes to make the painstaking observations that confirmed earlier hints of this planet's unique orbit.

The planet, called XO-3b, was discovered in 2007 through a method that depends on a chance alignment of the planet's orbit with the line-of-sight between its star and the Earth. Because of that alignment, the planet sometimes passes directly in front of the star as seen from here - an event called a transit - thus causing a slight dimming of the star's light. That dimming can be detected with a powerful telescope connected to a highly sensitive light meter, or photometer. Of the more than 350 exoplanets discovered so far, fewer than two dozen have been found through this transit method.

Detecting the planet itself was relatively easy, as it dimmed the star's light by about 1 percent. But to go one step further and measure the angle of its orbit, even with such powerful tools, means that "we have to be sneaky about it," Winn says. It turns out that if a planet crosses the star's disk at an angle to the star's own rotation, it causes a distinctive pattern of change in the overall color of the star, as measured by a highly sensitive spectrograph, because of the Doppler shifts caused by the star's rotation.

Hints of such a spectral signature were seen last year by another team, but that team acknowledged that they could not be confident of their result. The new observations, carried out by Winn and his team in February at the Keck I Observatory in Hawaii, provided a clear, solid measurement of the planet's distinctive tilt, determining the angle of the orbit to be about 37 degrees from the star's equator. The results are reported in a paper in the Astrophysical Journal, which was recently posted online and will be published in the journal's August issue.

A majority of the planets discovered so far orbiting other stars - known as exoplanets - are very large planets comparable to the gas giants in our solar system, but orbiting their stars much closer in (and thus faster). That's because the method used to detect these planets makes it much easier to detect such close-in giants than smaller or more distant ones. In the case of XO-3b, it is about 13 times as massive as Jupiter, yet orbits its star with a period, or "year," of just 3.5 days (Jupiter, by contrast, takes almost 12 years for an orbit). That size and closeness to its star are "unusual, even by the standards of exoplanets," Winn says.

Such "hot Jupiters" - so named because they resemble the solar system's largest planet, but would be much hotter because of their proximity to their parent stars - could not have formed in the places they are seen now, according to accepted planet-formation theory. They must have formed much further out from the star, then migrated inward to their present positions. Astronomers have come up with different mechanisms to account for the migration: the gravitational attraction of other planets as they passed close by, or the attraction of the disk of dust and gas from which the star and its planets formed.

Close encounters with other planets could greatly amplify a slight initial tilt, but attraction from the disk of material could not. So that theory could not account for a planet ending up on such a tilted orbit, which rules out that theory at least in the case of this particular planet.

In coming years, as new telescopes such as the Kepler space observatory begin to discover increasing numbers of exoplanets, "it will be interesting to identify more that are tilted, to find enough of them to be able to tease out patterns," Winn says.

In addition to Winn, the team included John Asher Johnson of the University of Hawaii; Daniel Fabrycky, Gil Esquerdo and Matthew Holman of the Harvard-Smithsonian Center for Astrophysics; Andrew Howard and Geoffrey Marcy of the University of California, Berkeley; Norio Narita of the National Observatory of Japan; Ian Crossfield of UCLA; Yasushi Suto of the University of Tokyo; and Edwin Turner of Princeton University. The work was funded by the NASA Origins program, an NSF postdoctoral fellowship and World Premier International Research Center Initiative.

David Chandler, MIT News Office

Wednesday, June 17, 2009

CfA-Designed Exhibit on Black Holes Expected to "Pull In" Museum Visitors

Cambridge, MA - On Sunday, June 21, 2009, a new exhibit developed by educators and scientists at the Harvard-Smithsonian Center for Astrophysics (CfA) will open at the Boston Museum of Science. Titled BLACK HOLES: SPACE WARPS & TIME TWISTS, the traveling exhibition pulls visitors in to the modern search for real black holes -- the most mysterious and powerful objects in the universe.

Black holes are regions in space with gravity so powerful that nothing can escape, and where time and space are warped beyond our understanding. The exhibition will guide visitors on a journey to the edge of these strange objects to discover how the latest research is turning science fiction into fact, challenging our notions of space and time in the process.

"In this exhibition, we wanted to use the inherent fascination of black holes as a compelling vehicle to engage museum visitors in the larger story of how scientific discovery works - and how science is connected to human curiosity, imagination, and culture," said project director Mary Dussault.

CfA personnel spent two and a half years planning, designing and constructing the 2,500 square foot exhibition. Its interactive stations address a number of questions, such as:

  • What is a black hole?
  • Where are black holes?
  • How do we find black holes if they are really black?
  • What would happen if you fell into a black hole?
One feature sure to be popular: a station where visitors can experience their own black hole adventure. Using one of three "excursion pods," they will embark on a fantasy "adventure vacation" to the black hole at the center of our galaxy. As they make their way toward this "deep space dive," visitors explore the phenomena around the black hole, including warped space, the slowing of time, and the dangerous magnetic fields and radiation that could leave them stranded on their cosmic adventure.

As they travel through the exhibit, visitors carry their own bar-coded Explorer's Card, which they can use to collect discoveries and to generate a personalized website that only they can access. Once visitors return home, their journal becomes a personal portal to further black hole exploration and a platform for sharing their Black Holes experience with friends and family.

Black Holes was made possible by a generous grant from the National Science Foundation, with additional major support from the National Aeronautics and Space Administration (NASA). The exhibition will be on display at the Museum through September 7, 2009, and is included with regular Exhibit Halls admission. For more information on the Museum, visit

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

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics

Tuesday, June 16, 2009

Giant eruption reveals 'dead' star

Illustration of a magnetar. Magnetars are the most intensely magnetised objects in the Universe. Their magnetic fields are some 10 000 million times stronger than Earth’s. If a magnetar were to magically appear at half the Moon’s distance from Earth, its magnetic field would wipe the details off every credit card on Earth.
Credits: Magnetar Illustration: NASA, SGR0501+4516 burst data

High energy X-ray emission from SGR 0501+4516 observed by Integral.
XMM-Newton observations of the magnetar SGR 0501+4516.
Credits: ESA/INTEGRAL/IBIS-SIGRI (Rea et al. 2009)

An enormous eruption has found its way to Earth after travelling for many thousands of years across space. Studying this blast with ESA’s XMM-Newton and Integral space observatories, astronomers have discovered a dead star belonging to a rare group: the magnetars.

X-Rays from the giant outburst arrived on Earth on 22 August 2008, and triggered an automatic sensor on the NASA-led, international Swift satellite. Just twelve hours later, XMM-Newton zeroed in and began to collect the radiation, allowing the most detailed spectral study of the decay of a magnetar outburst.

The outburst lasted for more than four months, during which time hundreds of smaller bursts were measured. Nanda Rea from the University of Amsterdam led the team that performed the research. “Magnetars allow us to study extreme matter conditions that cannot be reproduced on Earth,” she says.

Magnetars are the most intensely magnetised objects in the Universe. Their magnetic fields are some 10 000 million times stronger than Earth’s. If a magnetar were to magically appear at half the Moon’s distance from Earth, its magnetic field would wipe the details off every credit card on Earth.

This particular magnetar, known as SGR 0501+4516, is estimated to lie about 15 000 light-years away, and was undiscovered until its outburst gave it away. An outburst takes place when the unstable configuration of the magnetic field pulls the magnetar’s crust, allowing matter to spew outwards in an exotic volcanic eruption. This matter tangles with the magnetic field which itself can change its configuration, releasing more energy. And this was where Integral came in.

Only five days after the big eruption, Integral detected highly energetic X-rays coming from the outburst, beyond the energy range that XMM-Newton can see. It is the first time such transient X-ray emission has been detected during the outburst. It disappeared within 10 days and was probably generated as the magnetic configuration changed.

Magnetar outbursts can supply as much energy to Earth as solar flares, despite the fact they are far across our Galaxy, whereas the Sun is at our celestial doorstep. There are two ideas as to how a magnetar forms. One is that it is the tiny core left behind after a highly magnetic star has died. But such magnetic stars are very rare, with just a few known in our Galaxy. Another suggestion is that during the death of a normal star, its tiny core is accelerated, providing a dynamo that strengthens its magnetic field, turning it into a magnetar.

Currently most astronomers favour the first idea but as yet they have no conclusive proof. “If we could just find a magnetar in a cluster of highly magnetic stars, that would prove it,” says Rea.

So far only 15 magnetars in total are known in our Galaxy. SGR 0501+4516 is the first new soft gamma repeater, one of the two types of magnetars, discovered after a decade of searches. So, astronomers continue to search for more, waiting for the next giant eruption. As for their newly discovered SGR 0501+4516, the team has been granted time to return and observe it again next year with XMM-Newton. Now they know where to look, they hope to detect the object in a quiescent state, rather than in outburst, so that they can study the calm after a big storm.

Notes for editors:

The first outburst of the new magnetar candidate SGR 0501+4516 by N. Rea, G.L. Israel, R. Turolla, P. Esposito, S. Mereghetti, D. Gotz, S. Zane, A. Tiengo, K. Hurley, M. Feroci, M. Still, V. Yershov, C. Winkler, R. Perna, F. Bernardini, P. Ubertini, L. Stella, S. Campana, M. van der Klis, P.M. Woods, was published yesterday in the online version of the Monthly Notices of the Royal Astronomical Society.

Monday, June 15, 2009

NERSC Helps Expose Cosmic Transients

This false-color image of our glowing galactic neighbor, the Andromeda Galaxy, was created by layering 400 individual images captured by the PTF camera in February 2009. In one pointing, the PTF camera has a seven-square-degree field of view, equivalent to approximately 25 full moons. (Palomar Transient Factory/Peter Nugent, Berkeley Lab)

BERKELEY, CA – An innovative new sky survey, called the Palomar Transient Factory (PTF), will utilize the unique tools and services offered by the U.S. Department of Energy’s (DOE’s) National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory (Berkeley Lab) to expose relatively rare and fleeting cosmic events, like supernovae and gamma ray bursts.

In fact, during the commissioning phase alone, the survey has already uncovered more than 40 supernovae, stellar explosions, and astronomers expect to discover thousands more each year. Such events occur about once a century in our own Milky Way galaxy and are visible for only a few months.

“This survey is a trail blazer in many ways – it is the first project dedicated solely to finding transient events, and as part of this mission we’ve worked with NERSC to develop an automated system that will sift through terabytes of astronomical data every night to find interesting events, and have secured time on some of the world’s most powerful ground-based telescopes to conduct immediate follow up observations as events are identified,” says Shrinivas Kulkarni, a professor of astronomy and planetary science at the California Institute of Technology (Caltech), and Director of Caltech Optical Observatories. He is also principle investigator of the PTF survey.

“This truly novel survey combines the power of a wide-field telescope, a high-resolution camera, and high-performance network and computing, as well as the ability to conduct rapid follow-up observations with telescopes around the globe for the first time,” says Peter Nugent, a computational staff scientist in Berkeley Lab’s Computational Research Division (CRD) and the NERSC Analytics Group. Nugent is also the Real-time Transient Detection Lead for the PTF project.

Every night the PTF camera – a 100-megapixel machine mounted on the 48-inch Samuel Oschin Telescope at Palomar Observatory in Southern California – will automatically snap pictures of the sky, then send those images to NERSC for archiving via a high-speed network provided by DOE’s Energy Sciences Network (ESnet) and the National Science Foundation’s (NSF’s) High Performance Wireless Research and Education Network (HPWREN).

At NERSC, computers running machine-learning algorithms in the Real-time Transient Detection pipeline scour the PTF observations for “transient” sources, cosmic objects that change in brightness or position, by comparing the new observations with all of the data collected from previous nights. Once an interesting event is discovered, machines at NERSC will immediately, within minutes, send its coordinates to Palomar’s 60-inch telescope and others for follow up observations.

“PTF is an example of the growing need to provide data services for science; it combines automated, real-time analysis with high-end systems and networks in a way that changes the way the scientific community works,” says NERSC Director Kathy Yelick.

“We are currently uncovering one event every 12 minutes. This project will be keeping the astronomical community busy for quite a while,” says Kulkarni.

“These tools are extremely valuable because they not only help us identify supernova, they uncover them while the star is in the act of exploding,” says Robert Quimby of Caltech, who is the software lead for the PTF program. “This gives us valuable information about how cosmic dust is spread across the universe.”

He notes that all chemical elements in the universe besides hydrogen and helium are created inside stars. When massive stars die in fiery supernova explosions, they blast these chemical creations out into space. The cosmic dust will eventually come together to form stars, planets, comets – even humans. Everything around us is made of stardust.

In addition to spreading stardust across the cosmos, some species of supernovae also play a vital role in helping us understand the nature of the universe. For example, because Type Ia supernova are relatively uniform in brightness, they act as cosmic lighthouses, helping astronomers judge distance. Many astronomers participating in the PTF survey are specifically searching for these cosmic creatures.

“It is very exciting to find so many supernovae, so early in the project. It’s like we’ve just turned on the spigot and are now waiting for the fire hose to blast,” says Quimby.

Astronomers using NERSC’s Real-Time Detection pipeline uncovered supernova SN2009av-1a in the act of exploding. At left, the image of a galaxy 800 million light-years away was created by layering observations taken by the Palomar Transient Factory camera from February 23-27. Second from left is the image captured by the PTF camera on February 28. Next, using the NERSC pipeline to digitally subtract the earlier image from the new one, scientists exposed this cosmic transient, a supernova. At right, subtracting the previous images from one taken March 2 showed the source getting brighter. Follow-up observations caught the Type Ia supernova, now called SN2009av, at peak brightness. (Palomar Transient Factory/Dovi Poznanski, Berkeley Lab)

PTF is a collaboration of Berkeley Lab, Caltech, Columbia University, the NSF’s HPWREN, the Infrared Processing and Analysis Center, Las Cumbres Observatory Global Telescope Network, Oxford University, University of California at Berkeley, and the Weizmann Institute of Science, Israel. PTF is partly supported by DOE’s Scientific Discovery through Advanced Computing program; NERSC provided the storage and systems infrastructure. NERSC and ESnet are managed by the Berkeley Lab on behalf of the Office of Advanced Scientific Computing Research within the DOE Office of Science.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at

Contact: Linda Vu, (510) 495-2402

Additional information:

Read Caltech’s press release on the PTF at

Saturday, June 13, 2009

What's Next for Hubble?


When the crew of the Space Shuttle Atlantis released the Hubble Space Telescope to return to orbit, concluding the final astronaut mission to upgrade and repair Hubble, astronomy fans around the world rejoiced. Hubble, renewed and equipped with new cameras, would now return to its work of revealing the universe.

But after the furor and high-profile feats of a servicing mission, Hubble sinks into silence. This time, a three-month hiatus will take place between the mission and any new images.

The quiet belies the intense activity going on behind the scenes. Engineers and scientists are conducting a slow, painstaking process of bringing the telescope to full functionality, making the adjustments and gathering the information that will allow them to provide the best, clearest, cleanest images.

The process is known as Servicing Mission Observatory Verification (SMOV). Teams at the Space Telescope Science Institute in Baltimore, Md., and Goddard Space Flight Center in Greenbelt, Md., work together to make sure the telescope is pointing correctly and that its instruments are working with their intended precision.

Hubble's pointing is adjusted with the help of six gyroscopes, all of which were replaced during Servicing Mission 4. To ensure that the telescope is pointing accurately, engineers change the direction of the telescope in a measured way, and then examine the data generated from the gyroscopes. The data is then used to calibrate the gyroscopes to ensure precise pointing.

Next, engineers and scientists look at Hubble's instruments. The instruments are in the natural process of "outgassing" — the extra, unwanted molecules within them from their time on Earth are floating away due to the lack of atmospheric pressure.

Outgassing is important for a couple of reasons: the molecules can interfere with the instrument when high voltages are present, possibly damaging it; and they can absorb wavelengths of light, preventing the instrument from collecting all the information it could. To avoid these dangers, engineers wait until the outgassing is complete before bringing the instruments to full power.

The new instruments — weightless for the first time, and now in the vacuum of space — will be out of alignment. But that's expected, so the instruments are built with mechanisms that allow engineers to adjust them from the ground, often by moving small mirrors within the instrument itself. Each instrument needs a few weeks to go through the alignment process.

Finally, engineers take the instruments through a calibration process. Calibration is the process of identifying and dealing with data that belongs to the instrument, versus data that belongs to the sky.

Engineers observe a familiar astronomical object and compare the data they receive with the data they know should be there. They can then adjust the instruments to remove the data that comes from the instrument itself, or, more frequently, arrange to have it removed on the ground. Finding and identifying this erroneous data is a major part of the SMOV process.

Once all these tasks, have reached a particular point in the plan, Hubble starts taking its Early Release Observations (EROs), the first high-quality images from the telescope. The targets have been chosen in advance by a team that selects them for their ability to showcase Hubble's new capabilities.

The targets are kept a mystery until their release, but the goal is to provide the most impressive views of a good mix of astronomical objects — some within the galaxy, some far beyond.

To those who know what to look for, the new images will be the first true display of the power of Hubble's new technology, dazzling amateur and professional astronomers with a wealth of new information. Scientists will immediately have access to the images for use in their research. These compelling images are expected to be released in September.

As the ERO images are completed, Hubble will go back to the day-to-day task of observing the universe. Equipped with new eyes and fresh technology, it will work ceaselessly, minute by minute, to answer the pressing questions of modern astronomy. Though the servicing missions may be over, Hubble's revelations will continue far into the future.

Thursday, June 11, 2009

New definition could further limit habitable zones around distant suns

Artist's impression of the planetary system around the red dwarf Gliese 581. Using the instrument HARPS on the ESO 3.6-m telescope, astronomers have uncovered 3 planets, all of relative low-mass: 5, 8 and 15 Earth masses. The five Earth-mass planet (seen in foreground - Gliese 581 c) makes a full orbit around the star in 13 days, the other two in 5 (the blue, Neptunian-like planet - Gliese 581 b) and 84 days (the most remote one, Gliese 581 d). Credit: ESO

As astronomers gaze toward nearby planetary systems in search of life, they are focusing their attention on each system's habitable zone, where heat radiated from the star is just right to keep a planet's water in liquid form.

A number of planets have been discovered orbiting red dwarf stars, which make up about three-quarters of the stars close to our solar system. Potentially habitable planets must orbit close to those stars -- perhaps one-fiftieth the distance of Earth to the sun -- since those stars are smaller and generate less heat than our sun.

But new calculations indicate that, with planets so close, tidal forces exerted on planets by the parent star's gravity could limit what is regarded as a star's habitable zone and change the criteria for planets where life could potentially take root.

Scientists believe liquid water is essential for life. But a planet also must have plate tectonics to pull excess carbon from its atmosphere and confine it in rocks to prevent runaway greenhouse warming. Tectonics, or the movement of the plates that make up a planet's surface, typically is driven by radioactive decay in the planet's core, but a star's gravity can cause tides in the planet, which creates more energy to drive plate tectonics.

"If you have plate tectonics, then you can have long-term climate stability, which we think is a prerequisite for life," said Rory Barnes, a University of Washington postdoctoral researcher in astronomy.

However, tectonic forces cannot be so severe that geologic events quickly repave a planet's surface and destroy life that might have gotten a foothold, he said. The planet must be at a distance where tugging from the star's gravitational field generates tectonics without setting off extreme volcanic activity that resurfaces the planet in too short a time for life to prosper.

Barnes is lead author of a paper to be published by The Astrophysical Journal Letters that uses new calculations from computer modeling to define a "tidal habitable zone." Co-authors are Brian Jackson and Richard Greenberg from the University of Arizona and Sean Raymond from the University of Colorado. The research was funded by NASA.

"Overall, the effect of this work is to reduce the number of habitable environments in the universe, or at least what we have thought of as habitable environments," Barnes said. "The best places to look for habitability are where this new definition and the old definition overlap."

The new calculations have implications for planets previously considered too small for habitability. An example is Mars, which used to experience tectonics but that activity ceased as heat from the planet's decaying inner core dissipated.

But as planets get closer to their suns, the gravitational pull gets stronger, tidal forces increase and more energy is released. If Mars were to move closer to the sun, the sun's tidal tugs could possibly restart the tectonics, releasing gases from the core to provide more atmosphere. If Mars harbors liquid water, at that point it could be habitable for life as we know it.

Various moons of Jupiter have long been considered as potentially harboring life. But one of them, Io, has so much volcanic activity, the result of tidal forces from Jupiter, that it is not regarded as a good candidate. Tectonic activity remakes Io's surface in less than 1 million years.

"If that were to happen on Earth, it would be hard to imagine how life would develop," Barnes said.

A potential Earth-like planet, but eight times more massive, called Gliese 581d was discovered in 2007 about 20 light years away in the constellation Libra. At first it was thought the planet was too far from its sun, Gliese 581, to have liquid water, but recent observations have determined the orbit is within the habitable zone for liquid water. However, the planet is outside the habitable zone for its sun's tidal forces, which the authors believe drastically limits the possibility of life.

"Our model predicts that tides may contribute only one-quarter of the heating required to make the planet habitable, so a lot of heat from decay of radioactive isotopes may be required to make up the difference," Jackson said.

Barnes added, "The bottom line is that tidal forcing is an important factor that we are going to have to consider when looking for habitable planets."

For more information:

Contact Barnes at 206-543-8979 or

The paper is available a: