Wednesday, September 30, 2009

Stripped down: Hubble highlights two galaxies that are losing it

NGC 4522 and NGC 4402

This image shows NGC 4402 within the context of the Virgo Cluster.
Credit: NASA, ESA and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

This image shows NGC 4522 within the context of the Virgo Cluster.
Credit: NASA, ESA and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

A newly released set of images, taken by the NASA/ESA Hubble Space Telescope before the recent Servicing Mission, highlight the ongoing drama in two galaxies in the Virgo Cluster affected by a process known as "ram pressure stripping", which can result in peculiar-looking galaxies. An extremely hot X-ray emitting gas known as the intra-cluster medium lurks between galaxies within clusters. As galaxies move through this intra-cluster medium, strong winds rip through galaxies distorting their shape and even halting star formation.

Ram pressure is the drag force that results when something moves through a fluid — much like the wind you feel in your face when bicycling, even on a still day — and occurs in this context as galaxies orbiting about the centre of the cluster move through the intra-cluster medium, which then sweeps out gas from within the galaxies.

The spiral galaxy NGC 4522 is located some 60 million light-years away from Earth and it is a spectacular example of a spiral galaxy currently being stripped of its gas content. The galaxy is part of the Virgo galaxy cluster and its rapid motion within the cluster results in strong winds across the galaxy as the gas within is left behind. Scientists estimate that the galaxy is moving at more than 10 million kilometres per hour. A number of newly formed star clusters that developed in the stripped gas can be seen in the Hubble image.

Even though this is a still image, Hubble's view of NGC 4522 practically swirls off the page with apparent movement. It highlights the dramatic state of the galaxy, with an especially vivid view of the ghostly gas being forced out of it. Bright blue pockets of new star formation can be seen to the right and left of centre. The image is sufficiently deep to show distant background galaxies.

The image of NGC 4402 also highlights some telltale signs of ram pressure stripping such as the curved, or convex, appearance of the disc of gas and dust, a result of the forces exerted by the heated gas. Light being emitted by the disc backlights the swirling dust that is being swept out by the gas. Studying ram pressure stripping helps astronomers better understand the mechanisms that drive the evolution of galaxies, and how the rate of star formation is suppressed in very dense regions of the Universe like clusters.

Both images were taken by the Advanced Camera for Surveys on Hubble before it suffered from a power failure in 2007. Astronauts on Servicing Mission 4 in May 2009 were able to restore ACS during their 13-day mission.

Notes for editors: The Hubble Space Telescope is a project of international cooperation between ESA and NASA. Image credit: NASA & ESA
Contacts:

Colleen Sharkey Hubble/ESA, Garching, Germany Tel: +49 89 3200 6306 Cell: +49 151 153 73591 E-mail: csharkey@eso.org

Monday, September 28, 2009

The Trilogy is Complete — GigaGalaxy Zoom Phase 3

ESO PR Photo 36a/09
370-million-pixel starscape
of the Lagoon Nebula

ESO PR Photo 36b/09
The GigaGalaxy Zoom composite

ESO PR Video 36a/09
Diving into the Lagoon Nebula

ESO PR Video 36b/09
Pan over the Lagoon Nebula


The third image of ESO’s GigaGalaxy Zoom project has just been released online, completing this eye-opening dive into our galactic home in outstanding fashion. The latest image follows on from views, released over the last two weeks, of the sky as seen with the unaided eye and through an amateur telescope. This third instalment provides another breathtaking vista of an astronomical object, this time a 370-million-pixel view of the Lagoon Nebula of the quality and depth needed by professional astronomers in their quest to understand our Universe.

The newly released image extends across a field of view of more than one and a half square degree — an area eight times larger than that of the full Moon — and was obtained with the Wide Field Imager attached to the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. This 67-million-pixel camera has already created several of ESO’s iconic pictures.

The intriguing object depicted here — the Lagoon Nebula — is located four to five thousand light-years away towards the constellation of Sagittarius (the Archer). The nebula is a giant interstellar cloud, 100 light-years across, where stars are forming. The scattered dark patches seen all over the nebula are huge clouds of gas and dust that are collapsing under their own weight and which will soon give birth to clusters of young, glowing stars. Some of the smallest clouds are known as “globules” and the most prominent ones have been catalogued by the astronomer Edward Emerson Barnard.

The Lagoon Nebula hosts the young open stellar cluster known as NGC 6530. This is home for 50 to 100 stars and twinkles in the lower left portion of the nebula. Observations suggest that the cluster is slightly in front of the nebula itself, though still enshrouded by dust, as revealed by reddening of the starlight, an effect that occurs when small dust particles scatter light.

The name of the Lagoon Nebula derives from the wide lagoon-shaped dark lane located in the middle of the nebula that divides it into two glowing sections.

This gorgeous starscape is the last in the series of three huge images featured in the GigaGalaxy Zoom project, launched by ESO as part of the International Year of Astronomy 2009 (IYA2009). Through three giant images, the GigaGalaxy Zoom project reveals the full sky as it appears with the unaided eye from one of the darkest deserts on Earth, then zooms in on a rich region of the Milky Way using an amateur telescope, and finally uses the power of a professional telescope to reveal the details of a famous nebula. In this way, the project links the sky we can all see with the deep, “hidden” cosmos that astronomers study on a daily basis. The wonderful quality of the images is a testament to the splendour of the night sky at ESO’s sites in Chile, which are the most productive astronomical observatories in the world.

“The GigaGalaxy Zoom project’s dedicated website has proved very successful, drawing hundreds of thousands of visitors from all around the world,” says project coordinator Henri Boffin. “With the trilogy now complete, viewers will be able to explore a magnificently detailed cosmic environment on many different scales and take a breathtaking dive into our Milky Way.”

Links

* The GigaGalaxy Zoom web site is at http://www.gigagalaxyzoom.org
* La Silla web page
* The Lagoon Nebula page on GigaGalaxy Zoom

More Information

As part of the IYA2009, ESO is participating in several remarkable outreach activities, in line with its world-leading rank in the field of astronomy. ESO is hosting the IYA2009 Secretariat for the International Astronomical Union, which coordinates the Year globally. ESO is one of the Organisational Associates of IYA2009, and was also closely involved in the resolution submitted to the United Nations (UN) by Italy, which led to the UN’s 62nd General Assembly proclaiming 2009 the International Year of Astronomy. In addition to a wide array of activities planned both at the local and international level, ESO is leading four of the thirteen global Cornerstone Projects.

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”.

The third image of the GigaGalaxy Zoom project was taken with the Wide Field Imager (WFI) attached to the MPG/ESO 2.2-metre telescope at the ESO La Silla Observatory. In order to optimise telescope time, the images were obtained by ESO staff astronomers, who select the most favourable observations to be made at any given time, taking into account the visibility of the objects and the sky conditions. The La Silla Observatory, 600 km north of Santiago de Chile and at an altitude of 2400 metres, has been an ESO stronghold since the 1960s. Here, ESO operates several of the most productive 2–4-metre-class telescopes in the world.

Contacts

Henri Boffin, Olivier Hainaut
ESO, Garching, Germany
Phone: +49 89 3200 6222, +49 89 3200 6752
E-mail: hboffin@eso.org, ohainaut@eso.org

ESO Press Officer in Chile: Valeria Foncea - +56 2 463 3123 - vfoncea@eso.org

National contacts for the media: http://www.eso.org/public/outreach/eson/

Thursday, September 24, 2009

Keck Interferometer Nuller Spots Double Dust Cloud

Credit: NASA/GSFC/Marc Kuchner and Francis Reddy
This graphic compares the inner and outer disk of the 51 Oph system to the location of the planets and asteroid belt of the Solar System.

KAMUELA, Hawaii (Sept. 24, 2009) — Linking the twin, 10-meter telescopes in Hawaii, astronomers at the W. M. Keck Observatory discovered an extended, double-layered dust disk orbiting 51 Ophiuchi, a star that is 410 light-years from Earth. It is the first time the Keck Interferometer Nuller instrument has identified such a compact cloud around a star so far away.

The new data suggest that 51 Ophiuchi is a protoplanetary system with a dust cloud that orbits extremely close to its parent star, said University of Maryland astronomer Christopher Stark, who led the research team.

Keck Observatory operates one of the largest optical interferometers in the United States. The interferometer provides high precision resolution measurements equal to a telescope as large as the distance that separates the telescope’s primary mirrors—85 meters in the case of the Keck twins. In April 2007, the team simultaneously pointed both Keck telescopes at the star 51 Ophiuchi, or 51 Oph, and used the Interferometer’s Nuller, a technique to combine the incoming light in a particular way, to block the unwanted starlight of 51 Oph and measure faint adjacent signals from the dust cloud surrounding the star.

According to the observations, excess material orbited 51 Oph. Stark and his collaborators repeated the nulling measurements at several different wavelengths of light and combined this data with information from other telescopes to determine the shape and orientation of the material as well as the sizes of the dust grains.

The data suggest that two debris disks orbit 51 Oph. The inner disk has larger grains, roughly 10 micrometers or larger in diameter, and extends out to four astronomical units, or AUs, beyond the star. The second disk comprised of mainly 0.1 micrometer grains extends from roughly seven AU to 1200 AU. One AU is the distance between Earth and the Sun or roughly 93 million miles. The new results appear in the Oct. 1 Astrophysical Journal.

If these debris disks orbited the Sun, the inner cloud of larger grains would extend roughly from the position of Mercury’s orbit to just past the edge of the asteroid belt. The outer disk of smaller grains would originate just before Saturn’s orbit and extend to a distance ten times farther than the edge of the Kuiper belt.

51 Oph’s inner, compact dust disk is one of the most compact dust clouds ever detected, and the new Keck Interferometer Nuller observations demonstrate the instrument’s ability to detect dust clouds a hundred times smaller than a conventional telescope can observe, Stark said.

The instrument was also essential to solving the mystery of what made 51 Oph’s dust disk appear so compact while its spectra, or chemical fingerprints, suggested that the dust orbited at much larger distances, added Marc Kuchner, an astronomer at NASA’s Goddard Space Flight Center in Greenbelt, Md. who was part of the research team. The answer was simply that the star had two debris disks.

Because of the power of the Keck Nuller, Stark and his team were able to resolve inner and outer dust disks, which together form 51 Oph’s exozodiacal cloud. In similar star systems, the outer cloud of dust seems to be a distinct outer belt, probably analogous to the Kuiper belt or a second system of asteroids. But 51 Oph appears to be different, Kuchner said. The observations suggest that the star’s outer cloud is comprised of smaller grains and is connected to the inner cloud so that the system has only one underlying belt of asteroids.

This system most likely represents a rare, nearby example of a young planetary system just entering the late stages of planet formation. Terrestrial planets may be forming, although none have been detected within the system yet, Stark said.

His team’s data also indicates that the cloud around 51 Oph is 100,000 times more dense than the dust cloud circling the Solar System. In most planet-forming systems, as asteroid and comet collisions produce dust, the larger grains spiral toward the star while its outward pressure pushes smaller particles to the edge or even out of the system. 51 Ophiuchi, a star 260 times more luminous than the Sun, likely pushes the smaller dust grains from the inner disk to the outer disk, Kuchner explained.

Keck’s Nuller, which was funded by NASA and built by the Jet Propulsion Laboratory in Pasadena, Calif., will be used to help astronomers further understand how and when these asteroid belts form and how dust from the star’s debris disk might interfere with direct imaging of planets orbiting another star, he said.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawai’i. The twin telescopes feature a suite of advanced instrumentation including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and a world-leading laser-guide-star adaptive optics system. The Observatory is a scientific partnership of the California Institute of Technology, the University of California and NASA. For more information please call 808.881.3827 or visit http://www.keckobservatory.org.

Wednesday, September 23, 2009

The Pinwheel Galaxy

This fantastic image of the Pinwheel Galaxy was obtained using the Wide Field Camera on the Isaac Newton Telescope. It´s a three-colour composite made from data collected through the filters Sloan g´, r´+Hα and i´. Credit: R. Barrena and D. López (IAC). [ JPEG | TIFF | PDF (with text) ].

The Pinwheel Galaxy, also known as Messier 101 or NGC 5457, is a grand-design spiral galaxy located at a distance of about 27 million light-years from Earth. It is nearly twice the size of our Milky Way.

M101 is usually referred as a classical example of an spiral galaxy. The observed deviation from symmetry is associated with a recent galaxy encounter, that triggered strong star formation visible now as bright HII regions, or the red spots in the image shown above.

This image was obtained and processed by members of the IAC astrophotography group (A. Oscoz, D. López, P. Rodríguez-Gil and L. Chinarro).

More information:
M101 - IAC astrophoto August 2009
IAC Astronomical Picture of the Month

Javier Méndez
Public Relations Officer

NASA's Spitzer Spots Clump of Swirling Planetary Material

Lump of Planetary Stuff
Credit: NASA/JPL-Caltech/R. Hurt (SSC)

About this image: This artist's conception shows a lump of material in a swirling, planet-forming disk. Astronomers using NASA's Spitzer Space Telescope found evidence that a companion to a star -- either another star or a planet -- could be pushing planetary material together, as illustrated here.

Planets are born out of spinning disks of gas and dust. They can carve out lanes or gaps in the disks as they grow bigger and bigger. Scientists used Spitzer's infrared vision to study the disk around a star called LRLL 31, located about 1,000 light-years away in the IC 348 region of the constellation Perseus. Spitzer's new infrared observations reveal that the disk has both an inner and outer gap.

What's more, the data show that infrared light from the disk is changing over as little time as one week -- a very unusual occurrence. In particular, light of different wavelengths seesawed back and forth, with short-wavelength light going up when long-wavelength light went down, and vice versa.

According to astronomers, this change could be caused by a companion to the star (illustrated as a planet in this picture). As the companion spins around, its gravity would cause the wall of the inner disk to squeeze into a lump. This lump would also spin around the star, shadowing part of the outer disk. When the bright side of the lump is on the far side of the star, and facing Earth, more infrared light at shorter wavelengths should be observed (hotter material closer to the star emits shorter wavelengths of infrared light). In addition, the shadow of the lump should cause longer-wavelength infrared light from the outer disk to decrease. The opposite would be true when the lump is in front of the star and its bright side is hidden (shorter-wavelength light would go down, and longer-wavelength light up). This is precisely what Spitzer observed.

The size of the lump and the planet have been exaggerated to better illustrate the dynamics of the system.

PASADENA, Calif. — Astronomers have witnessed odd behavior around a young star. Something, perhaps another star or a planet, appears to be pushing a clump of planet-forming material around. The observations, made with NASA's Spitzer Space Telescope, offer a rare look into the early stages of planet formation.

Planets form out of swirling disks of gas and dust. Spitzer observed infrared light coming from one such disk around a young star, called LRLL 31, over a period of five months. To the astronomers' surprise, the light varied in unexpected ways, and in as little time as one week. Planets take millions of years to form, so it's rare to see anything change on time scales we humans can perceive.

One possible explanation is that a close companion to the star — either a star or a developing planet — could be shoving planet-forming material together, causing its thickness to vary as it spins around the star.

"We don't know if planets have formed, or will form, but we are gaining a better understanding of the properties and dynamics of the fine dust that could either become, or indirectly shape, a planet," said James Muzerolle of the Space Telescope Science Institute, Baltimore, Md. Muzerolle is first author of a paper accepted for publication in the Astrophysical Journal Letters. "This is a unique, real-time glimpse into the lengthy process of building planets."

One theory of planet formation suggests that planets start out as dusty grains swirling around a star in a disk. They slowly bulk up in size, collecting more and more mass like sticky snow. As the planets get bigger and bigger, they carve out gaps in the dust, until a so-called transitional disk takes shape with a large doughnut-like hole at its center. Over time, this disk fades and a new type of disk emerges, made up of debris from collisions between planets, asteroids and comets. Ultimately, a more settled, mature solar system like our own forms.

Before Spitzer was launched in 2003, only a few transitional disks with gaps or holes were known. With Spitzer's improved infrared vision, dozens have now been found. The space telescope sensed the warm glow of the disks and indirectly mapped out their structures.

Muzerolle and his team set out to study a family of young stars, many with known transitional disks. The stars are about two to three million years old and about 1,000 light-years away, in the IC 348 star-forming region of the constellation Perseus. A few of the stars showed surprising hints of variations. The astronomers followed up on one, LRLL 31, studying the star over five months with all three of Spitzer's instruments.

The observations showed that light from the inner region of the star's disk changes every few weeks, and, in one instance, in only one week. "Transition disks are rare enough, so to see one with this type of variability is really exciting," said co-author Kevin Flaherty of the University of Arizona, Tucson.

Both the intensity and the wavelength of infrared light varied over time. For instance, when the amount of light seen at shorter wavelengths went up, the brightness at longer wavelengths went down, and vice versa.

Muzerolle and his team say that a companion to the star, circling in a gap in the system's disk, could explain the data. "A companion in the gap of an almost edge-on disk would periodically change the height of the inner disk rim as it circles around the star: a higher rim would emit more light at shorter wavelengths because it is larger and hot, but at the same time, the high rim would shadow the cool material of the outer disk, causing a decrease in the longer-wavelength light. A low rim would do the opposite. This is exactly what we observe in our data," said Elise Furlan, a co-author from NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The companion would have to be close in order to move the material around so fast — about one-tenth the distance between Earth and the sun.

The astronomers plan to follow up with ground-based telescopes to see if a companion is tugging on the star hard enough to be perceived. Spitzer will also observe the system again in its "warm" mission to see if the changes are periodic, as would be expected with an orbiting companion. Spitzer ran out of coolant in May of this year, and is now operating at a slightly warmer temperature with two infrared channels still functioning.

"For astronomers, watching anything in real-time is exciting," said Muzerolle. "It's like we're biologists getting to watch cells grow in a petri dish, only our specimen is light-years away."

Other authors are Zoltan Balog, Max Planck Institute for Astronomy, Germany; Paul S. Smith and George Rieke, University of Arizona; Lori Allen, National Optical Astronomy Observatory, Tucson; Nuria Calvet, University of Michigan, Ann Arbor; Paola D'Alessio, National Autonomous University of Mexico; S. Thomas Megeath, University of Toledo, Ohio; August Muench, Harvard-Smithsonian Center for Astrophysics, Cambridge; William H. Sherry, National Solar Observatory, Tucson.

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

whitney.clavin@jpl.nasa.gov

ssc2009-18
jpl2009-146


Printable version (PDF) of this release

Tuesday, September 22, 2009

High-School Student Discovers Strange Astronomical Object


When Lucas Bolyard looked at the bottom plot, he noticed the thick, black blob left of the center. He saw that this signal was positioned on the graph where it indicated a non-zero "dispersion measure," or DM. Dispersion measure is used by astronomers as an indicator of cosmic distances. The non-zero DM value of this pulse is a clue that the signal came from space, not from Earth. The other blobs on the bottom of the graph are signals at a distance of zero-- that is from here on Earth.

Lucas Bolyard
CREDIT: NRAO/AUI/NSF

Robert C. Byrd Green Bank Telescope
CREDIT: NRAO/AUI/NSF

A West Virginia high-school student analyzing data from a giant radio telescope has discovered a new astronomical object -- a strange type of neutron star called a rotating radio transient.

Lucas Bolyard, a sophomore at South Harrison High School in Clarksburg, WV, made the discovery while participating in a project in which students are trained to scrutinize data from the National Science Foundation's giant Robert C. Byrd Green Bank Telescope (GBT).

The project, called the Pulsar Search Collaboratory (PSC), is a joint project of the National Radio Astronomy Observatory (NRAO) and West Virginia University (WVU), funded by a grant from the National Science Foundation.

Bolyard made the discovery in March, after he already had studied more than 2,000 data plots from the GBT and found nothing.

"I was home on a weekend and had nothing to do, so I decided to look at some more plots from the GBT," he said. "I saw a plot with a pulse, but there was a lot of radio interference, too. The pulse almost got dismissed as interference," he added.

Nonetheless, he reported it, and it went on a list of candidates for West Virginia University astronomers Maura McLaughlin and Duncan Lorimer to re-examine, scheduling new observations of the region of sky from which the pulse came. Disappointingly, the follow-up observations showed nothing, indicating that the object was not a normal pulsar. However, the astronomers explained to Bolyard that his pulse still might have come from a rotating radio transient.

Confirmation didn't come until July. Bolyard was at the NRAO's Green Bank Observatory with fellow PSC students. The night before, the group had been observing with the GBT in the wee hours, and all were very tired. Then Lorimer showed Bolyard a new plot of his pulse, reprocessed from raw data, indicating that it is real, not interference, and that Bolyard is likely the discoverer of one of only about 30 rotating radio transients known.

Suddenly, Bolyard said, he wasn't tired anymore. "That news made me full of energy," he exclaimed.

Rotating radio transients are thought to be similar to pulsars, superdense neutron stars that are the corpses of massive stars that exploded as supernovae. Pulsars are known for their lighthouse-like beams of radio waves that sweep through space as the neutron star rotates, creating a pulse as the beam sweeps by a radio telescope. While pulsars emit these radio waves continuously, rotating radio transients emit only sporadically, one burst at a time, with as much as several hours between bursts. Because of this, they are difficult to discover and observe, with the first one only discovered in 2006.

"These objects are very interesting, both by themselves and for what they tell us about neutron stars and supernovae," McLaughlin said. "We don't know what makes them different from pulsars -- why they turn on and off. If we answer that question, it's likely to tell us something new about the environments of pulsars and how their radio waves are generated," she added.

"They also tell us there are more neutron stars than we knew about before, and that means there are more supernova explosions. In fact, we now almost have more neutron stars than can be accounted for by the supernovae we can detect," McLaughlin explained.

The PSC, led by NRAO Education Officer Sue Ann Heatherly and Project Director Rachel Rosen, includes training for teachers and student leaders, and provides parcels of data from the GBT to student teams. The project involves teachers and students in helping astronomers analyze data from 1500 hours of observing with the GBT. The 120 terabytes of data were produced by 70,000 individual pointings of the giant, 17-million-pound telescope. Some 300 hours of the observing data were reserved for analysis by student teams.

The student teams use analysis software to reveal evidence of pulsars. Each portion of the data is analyzed by multiple teams. In addition to learning to use the analysis software, the student teams also must learn to recognize man-made radio interference that contaminates the data. The project will continue through 2011.

"The students get to actually look through data that has never been looked through before," Rosen said. From the training, she added, "the students get a wonderful grasp of what they're looking at, and they understand the science behind the plots that they're looking at."

For at least one student, the PSC has brought to life the excitement of discovery. "Science is a lot more exciting for me now that I've made this discovery," Bolyard said. Scientific research, he learned, "is a lot of hard work, but it's worth it!"

A year ago, he said, he wouldn't have thought of astronomy as a career, but the experience of discovery made astronomy at least a possibility for him. However, he added, "I'm still hoping to be a doctor."

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Galactic Center: New Vista of Milky Way Center Unveiled

Credit: NASA/CXC/UMass/D. Wang et al.


A dramatic new vista of the center of the Milky Way galaxy from NASA's Chandra X-ray Observatory exposes new levels of the complexity and intrigue in the Galactic center. The mosaic of 88 Chandra pointings represents a freeze-frame of the spectacle of stellar evolution, from bright young stars to black holes, in a crowded, hostile environment dominated by a central, supermassive black hole.

Permeating the region is a diffuse haze of X-ray light from gas that has been heated to millions of degrees by winds from massive young stars - which appear to form more frequently here than elsewhere in the Galaxy - explosions of dying stars, and outflows powered by the supermassive black hole - known as Sagittarius A* (Sgr A*). Data from Chandra and other X-ray telescopes suggest that giant X-ray flares from this black hole occurred about 50 and about 300 years earlier.

The area around Sgr A* also contains several mysterious X-ray filaments.
Some of these likely represent huge magnetic structures interacting with streams of very energetic electrons produced by rapidly spinning neutron stars or perhaps by a gigantic analog of a solar flare.

Scattered throughout the region are thousands of point-like X-ray sources. These are produced by normal stars feeding material onto the compact, dense remains of stars that have reached the end of their evolutionary trail - white dwarfs, neutron stars and black holes.

Because X-rays penetrate the gas and dust that blocks optical light coming from the center of the galaxy, Chandra is a powerful tool for studying the Galactic Center. This image combines low energy X-rays (colored red), intermediate energy X-rays (green) and high energy X-rays (blue).

The image is being released at the beginning of the "Chandra's First Decade of Discovery" symposium being held in Boston, Mass. This four-day conference will celebrate the great science Chandra has uncovered in its first ten years of operations. To help commemorate this event, several of the astronauts who were onboard the Space Shuttle Columbia - including Commander Eileen Collins - that launched Chandra on July 23, 1999, will be in attendance.

Fast Facts for Galactic Center:

Scale: Image is 120 by 48 arcmin
Category: Normal Galaxies & Starburst Galaxies, Milky Way Galaxy
Coordinates: (J2000) RA 17h 45m 23s | Dec -29° 01' 17
Constellation: Sagittarius
Observation Date: 88 pointings between 03/29/2000 - 07/19/2007
Observation Time: 26 days 3 hours
Obs. ID: 658,944-945, 1561, 2267-2296, 2943, 2951-2954, 3392-3393, 3549, 3663, 3665, 4500, 4683-4684, 5360, 5892, 5950-5954, 6113, 6363, 6639, 6640-6646, 7034-7048, 7345-7346, 7554-7557, 8214, 8459, 8567
Color Code Energy: Red (1-3 keV); Green (3-5 keV); Blue (5-8 keV)
Instrument: ACIS
References: M. P. Muno, et al., 2009 ApJS 181 110-128
Distance Estimate: About 26,000 light years

Monday, September 21, 2009

Zooming to the centre of the Milky Way — GigaGalaxy Zoom phase 2

ESO PR Photo 34a/09
A 340-million pixel starscape from Paranal

ESO PR Photo 34b/09
Astrophotographer Stéphane Guisard

ESO PR Photo 34c/09
GigagalaxyZoom Phase 2

ESO PR Video 34a/09
Zooming onto Messier 4

ESO PR Video 34b/09
Zooming onto Messier 8

The second of three images of ESO's GigaGalaxy Zoom project has just been released online. It is a new and wonderful 340-million-pixel vista of the central parts of our home galaxy as seen from ESO's Paranal Observatory with an amateur telescope.

This 34 by 20-degree wide image provides us with a view as experienced by amateur astronomers around the world. However, its incredible beauty and appeal owe much to the quality of the observing site and the skills of Stéphane Guisard, the world-renowned astrophotographer, who is also an ESO engineer. This second image directly benefits from the quality of Paranal's sky, one of the best on the planet, where ESO's Very Large Telescope is located. In addition, Guisard has drawn on his professional expertise as an optical engineer specialising in telescopes, a rare combination in the world of astrophotographers. Guisard, as head of the optical engineering team at Paranal, is responsible for ensuring that the Very Large Telescope has the best optical performance possible.

To create this stunning, true-colour mosaic of the Galactic Centre region, Guisard assembled about 1200 individual images, totalling more than 200 hours of exposure time, collected over 29 nights, during Guisard's free time, while working during the day at Paranal [1].

The image shows the region spanning the sky from the constellation of Sagittarius (the Archer) to Scorpius (the Scorpion). The very colourful Rho Ophiuchi and Antares region is a prominent feature to the right, although much darker areas, such as the Pipe and Snake nebulae also stand out. The dusty lane of our Milky Way runs obliquely through the image, dotted with remarkable bright, reddish nebulae, such as the Lagoon and the Trifid Nebulae, as well as NGC 6357 and NGC 6334. This dark lane also hosts the very centre of our Galaxy, where a supermassive black hole is lurking.

"The area I have depicted in this image is an incredibly rich region of the sky, and the one I find most beautiful," says Guisard.

This gorgeous starscape is the second of three extremely high resolution images featured in the GigaGalaxy Zoom project, launched by ESO as part of the International Year of Astronomy 2009 (IYA2009). The project allows stargazers to explore and experience the Universe as it is seen with the unaided eye from the darkest and best viewing locations in the world. GigaGalaxy Zoom features a web tool that allows users to take a breathtaking dive into our Milky Way. With this tool users can learn more about many different and exciting objects in the image, such as multicoloured nebulae and exploding stars, just by clicking on them. In this way, the project seeks to link the sky we can all see with the deep, "hidden" cosmos that astronomers study on a daily basis. The wonderful quality of the images is a testament to the splendour of the night sky at ESO's sites in Chile, which are the most productive astronomical observatories in the world.

The third GigaGalaxy Zoom image will be revealed next week, on 28 September 2009.
Note

[1] The image was obtained from Cerro Paranal, home of ESO's Very Large Telescope, by observing with a 10-cm Takahashi FSQ106Ed f/3.6 telescope and a SBIG STL CCD camera, using a NJP160 mount. The images were collected through three different filters (B, V and R) and then stitched together. This mosaic was assembled from 52 different sky fields made from about 1200 individual images totalling 200 hours exposure time, with the final image having a size of 24 403 x 13 973 pixels.

Links

The GigaGalaxy Zoom web site is at http://www.gigagalaxyzoom.org
Stéphane Guisard's Web site: www.eso.org/~sguisard

More Information

As part of the IYA2009, ESO is participating in several remarkable outreach activities, in line with its world-leading rank in the field of astronomy. ESO is hosting the IYA2009 Secretariat for the International Astronomical Union, which coordinates the Year globally. ESO is one of the Organisational Associates of IYA2009, and was also closely involved in the resolution submitted to the United Nations (UN) by Italy, which led to the UN's 62nd General Assembly proclaiming 2009 the International Year of Astronomy. In addition to a wide array of activities planned both at the local and international level, ESO is leading three of the twelve global Cornerstone Projects.

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".

A native of France, Guisard has worked for ESO in Chile since 1994, and is now the head Optics Engineer for ESO's Very Large Telescope (VLT). He is in charge of the optical alignment of the Paranal telescopes, as well as maintaining and improving the image quality of these telescopes and their active optics. Stéphane spends most of his free time photographing the night sky, enjoying the same crystal clear skies as the VLT. His fantastic astronomical images and time-lapse movies have been used in many books and TV programmes. Stéphane Guisard is also a photographer for The World At Night (TWAN).

Contacts

Stéphane Guisard
ESO, Chile
Phone: +56 55 43 5283
E-mail: sguisard@eso.org
Web: http://www.eso.org/~sguisard/

Henri Boffin, Olivier Hainaut
ESO, Garching, Germany
Phone: +49 89 3200 6222, +49 89 3200 6752
E-mail: hboffin@eso.org, ohainaut@eso.org

ESO Press Officer in Chile: Valeria Foncea - +56 2 463 3123 - vfoncea@eso.org

National contacts for the media: http://www.eso.org/public/outreach/eson/

Thursday, September 17, 2009

Planck first light yields promising results

HI-RES JPEG (Size: 1856 kb)
A map of the sky at optical wavelengths shows a prominent horizontal band which is the light shining from our own Milky Way. The superimposed strip shows the area of the sky mapped by Planck during the First Light Survey.

The colour scale indicates the magnitude of the deviations of the temperature of the Cosmic Microwave Background from its average value, as measured by Planck at a frequency close to the peak of the CMB spectrum (red is hotter and blue is colder).

The large red strips trace radio emission from the Milky Way, whereas the small bright spots high above the galactic plane correspond to emission from the Cosmic Microwave Background itself. Credits: ESA, LFI & HFI Consortia. Background optical image: Axel Mellinger

HI-RES MOV (Size: 13 600 Kb)
Planck will scan the entire sky to build the most accurate map ever of the Cosmic Microwave Background (CMB), the relic radiation from the Big Bang. The spacecraft will spin at 1 rotation per minute around an axis offset by about 85° so that the observed sky region will trace a large circle on the sky. As the spin axis follows the Sun the circle observed by the instruments sweeps through the sky at a rate of 1° per day. Planck will take about 6 months to complete a full scan of the sky, allowing the creation of two complete sky maps during the nominal mission lifetime (about 15 months). Credits: ESA (animation by C.Carreau)

Preliminary results from ESA’s Planck mission to study the early Universe indicate that the data quality is excellent. This bodes well for the full sky survey that has just begun.

Planck started surveying the sky regularly from its vantage point at the second Lagrange point of the Sun-Earth system, L2, on 13 August. The instruments were fine-tuned for optimum performance in the period preceding this date.

ESA's Planck microwave observatory is the first European mission designed to study the Cosmic Microwave Background – the relic radiation from the Big Bang.

Following launch on 14 May, checkouts of the satellite's subsystems were started in parallel with the cool-down of its instruments' detectors. The detectors are looking for variations in the temperature of the Cosmic Microwave Background that are about a million times smaller than one degree – this is comparable to measuring from Earth the body heat of a rabbit sitting on the Moon. To achieve this, Planck's detectors must be cooled to extremely low temperatures, some of them being very close to absolute zero (–273.15°C, or zero Kelvin, 0K).

With check-outs of the subsystems finished, instrument commissioning, optimisation, and initial calibration was completed by the second week of August.

The 'first light' survey, which began on 13 August, was a two-week period during which Planck surveyed the sky continuously. It was carried out to verify the stability of the instruments and the ability to calibrate them over long periods to the exquisite accuracy needed.

This survey was completed on 27 August, yielding maps of a strip of the sky, one for each of Planck's nine frequencies. Each map is a ring, about 15° wide, stretching across the full sky. Preliminary analysis indicates that the quality of the data is excellent.


Routine operations started as soon as the first light survey was completed, and surveying will now continue for at least 15 months without a break. In approximately 6 months, the first all-sky map will be assembled.

Within its allotted operational life of 15 months, Planck will gather data for two complete sky maps. To fully exploit the high sensitivity of Planck, the data will require delicate adjustments and careful analysis. It promises to return a treasure trove that will keep both cosmologists and astrophysicists busy for decades to come.

Credits are available in this pdf document on the International Participation in Herschel and Planck.

Wednesday, September 16, 2009

Swift Makes Best-ever Ultraviolet Portrait of Andromeda Galaxy

This mosaic of M31 merges 330 individual images taken by the Ultraviolet/Optical Telescope aboard NASA's Swift spacecraft. It is the highest-resolution image of the galaxy ever recorded in the ultraviolet. The image shows a region 200,000 light-years wide and 100,000 light-years high (100 arcminutes by 50 arcminutes). Credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)

This optical view from a ground-based telescope shows the Andromeda Galaxy in a more familiar light. This image encompasses the same area as the Swift mosaic. Credit: Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

M31 lies 2.5 million light-years away in the constellation Andromeda and is the nearest large spiral galaxy to our own. Under a clear, dark sky, it can be seen as a misty patch with the naked eye. Credit: Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

In a break from its usual task of searching for distant cosmic explosions, NASA's Swift satellite has acquired the highest-resolution view of a neighboring spiral galaxy ever attained in the ultraviolet. The galaxy, known as M31 in the constellation Andromeda, is the largest and closest spiral galaxy to our own.

"Swift reveals about 20,000 ultraviolet sources in M31, especially hot, young stars and dense star clusters," said Stefan Immler, a research scientist on the Swift team at NASA's Goddard Space Flight Center in Greenbelt, Md. "Of particular importance is that we have covered the galaxy in three ultraviolet filters. That will let us study M31's star-formation processes in much greater detail than previously possible."

M31, also known as the Andromeda Galaxy, is more than 220,000 light-years across and lies 2.5 million light-years away. On a clear, dark night, the galaxy is faintly visible as a misty patch to the naked eye.

Between May 25 and July 26, 2008, Swift's Ultraviolet/Optical Telescope (UVOT) acquired 330 images of M31 at wavelengths of 192.8, 224.6, and 260 nanometers. The images represent a total exposure time of 24 hours.

The task of assembling the resulting 85 gigabytes of images fell to Erin Grand, an undergraduate student at the University of Maryland at College Park who worked with Immler as an intern this summer. "After ten weeks of processing that immense amount of data, I'm extremely proud of this new view of M31," she said.

Several features are immediately apparent in the new mosaic. The first is the striking difference between the galaxy's central bulge and its spiral arms. "The bulge is smoother and redder because it's full of older and cooler stars," Immler explained. "Very few new stars form here because most of the materials needed to make them have been depleted."

Dense clusters of hot, young, blue stars sparkle beyond the central bulge. As in our own galaxy, M31's disk and spiral arms contain most of the gas and dust needed to produce new generations of stars. Star clusters are especially plentiful in an enormous ring about 150,000 light-years across.

What triggers the unusually intense star formation in Andromeda's "ring of fire"? Previous studies have shown that tides raised by the many small satellite galaxies in orbit around M31 help boost the interactions within gas clouds that result in new stars.

In 1885, an exploding star in M31's central bulge became bright enough to see with the naked eye. This was the first supernova ever recorded in any galaxy beyond our own Milky Way. "We expect an average of about one supernova per century in galaxies like M31," Immler said. "Perhaps we won't have to wait too long for another one."

"Swift is surveying nearby galaxies like M31 so astronomers can better understand star- formation conditions and relate them to conditions in the distant galaxies where we see gamma-ray bursts occurring," said Neil Gehrels, the mission's principal investigator at NASA Goddard. Since Swift's November 2005 launch, the satellite has detected more than 400 gamma-ray bursts -- massive, far-off explosions likely associated with the births of black holes.

Swift is managed by NASA Goddard. It was built and is being operated in collaboration with Pennsylvania State University, the Los Alamos National Laboratory in New Mexico, and General Dynamics of Gilbert, Ariz., in the United States. International collaborators include the University of Leicester and Mullard Space Sciences Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, and additional partners in Germany and Japan.

Related Link: Blueshift podcast: Swift sees Andromeda in a New Light

Francis Reddy
NASA's Goddard Space Flight Center

First Solid Evidence for a Rocky Exoplanet

Artist's impression of CoroT-7b

The planet-hosting star CoRoT-7

Field around the planet-hosting star CoRoT-7

Zoom in on the star CoRoT-7

Pan over the artist's impression of CoRoT-7b

Zoom in the artist's impression of CoRoT-7b

Mass and density of smallest exoplanet finally measured

The longest set of HARPS measurements ever made has firmly established the nature of the smallest and fastest-orbiting exoplanet known, CoRoT-7b, revealing its mass as five times that of Earth's. Combined with CoRoT-7b's known radius, which is less than twice that of our terrestrial home, this tells us that the exoplanet's density is quite similar to the Earth's, suggesting a solid, rocky world. The extensive dataset also reveals the presence of another so-called super-Earth in this alien solar system.

"This is science at its thrilling and amazing best," says Didier Queloz, leader of the team that made the observations. "We did everything we could to learn what the object discovered by the CoRoT satellite looks like and we found a unique system."

In February 2009, the discovery by the CoRoT satellite [1] of a small exoplanet around a rather unremarkable star named TYC 4799-1733-1 was announced one year after its detection and after several months of painstaking measurements with many telescopes on the ground, including several from ESO. The star, now known as CoRoT-7, is located towards the constellation of Monoceros (the Unicorn) at a distance of about 500 light-years. Slightly smaller and cooler than our Sun, CoRoT-7 is also thought to be younger, with an age of about 1.5 billion years.

Every 20.4 hours, the planet eclipses a small fraction of the light of the star for a little over one hour by one part in 3000 [2]. This planet, designated CoRoT-7b, is only 2.5 million kilometres away from its host star, or 23 times closer than Mercury is to the Sun. It has a radius that is about 80% greater than the Earth's.

The initial set of measurements, however, could not provide the mass of the exoplanet. Such a result requires extremely precise measurements of the velocity of the star, which is pulled a tiny amount by the gravitational tug of the orbiting exoplanet. The problem with CoRoT-7b is that these tiny signals are blurred by stellar activity in the form of "starspots" (just like sunspots on our Sun), which are cooler regions on the surface of the star. Therefore, the main signal is linked to the rotation of the star, with makes one complete revolution in about 23 days.

To get an answer, astronomers had to call upon the best exoplanet-hunting device in the world, the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph attached to the ESO 3.6-metre telescope at the La Silla Observatory in Chile.

"Even though HARPS is certainly unbeaten when it comes to detecting small exoplanets, the measurements of CoRoT-7b proved to be so demanding that we had to gather 70 hours of observations on the star," says co-author François Bouchy.

HARPS delivered, allowing the astronomers to tease out the 20.4-hour signal in the data. This figure led them to infer that CoRoT-7b has a mass of about five Earth masses, placing it in rare company as one of the lightest exoplanets yet found.

"Since the planet's orbit is aligned so that we see it crossing the face of its parent star — it is said to be transiting — we can actually measure, and not simply infer, the mass of the exoplanet, which is the smallest that has been precisely measured for an exoplanet [3]," says team member Claire Moutou. "Moreover, as we have both the radius and the mass, we can determine the density and get a better idea of the internal structure of this planet."

With a mass much closer to that of Earth than, for example, ice giant Neptune's 17 Earth masses, CoRoT-7b belongs to the category of "super-Earth" exoplanets. About a dozen of these bodies have been detected, though in the case of CoRoT-7b, this is the first time that the density has been measured for such a small exoplanet. The calculated density is close to Earth's, suggesting that the planet's composition is similarly rocky.

"CoRoT-7b resulted in a 'tour de force' of astronomical measurements. The superb light curves of the space telescope CoRoT gave us the best radius measurement, and HARPS the best mass measurement for an exoplanet. Both were needed to discover a rocky planet with the same density as the Earth," says co-author Artie Hatzes.

CoRoT-7b earns another distinction as the closest known exoplanet to its host star, which also makes it the fastest — it orbits its star at a speed of more than 750 000 kilometres per hour, more than seven times faster than the Earth's motion around the Sun. "In fact, CoRoT-7b is so close that the place may well look like Dante's Inferno, with a probable temperature on its 'day-face' above 2000 degrees and minus 200 degrees on its night face. Theoretical models suggest that the planet may have lava or boiling oceans on its surface. With such extreme conditions this planet is definitively not a place for life to develop," says Queloz.

As a further testament to HARPS' sublime precision, the astronomers found from their dataset that CoRoT-7 hosts another exoplanet slightly further away than CoRoT-7b. Designated CoRoT-7c, it circles its host star in 3 days and 17 hours and has a mass about eight times that of Earth, so it too is classified as a super-Earth. Unlike CoRoT-7b, this sister world does not pass in front of its star as seen from Earth, so astronomers cannot measure its radius and thus its density.

Given these findings, CoRoT-7 stands as the first star known to have a planetary system made of two short period super-Earths with one that transits its host.

Notes

[1] The CoRoT mission is a cooperation between France and its international partners: ESA, Austria, Belgium, Brazil, Germany and Spain.

[2] We see exactly the same effect in our Solar System when Mercury or Venus transits the solar disc, as Venus did on 8 June 2004 (ESO PR 03/04). In the past centuries such events were used to estimate the Sun-Earth distance, with extremely useful implications for astrophysics and celestial mechanics.

[3] Gliese 581e, also discovered with HARPS, has a minimum mass about twice the Earth's mass (see ESO 15/09), but the exact geometry of the orbit is undefined, making its real mass unknown. In the case of CoRoT-7b, as the planet is transiting, the geometry is well defined, allowing the astronomers to measure the mass of the planet precisely.

More Information

This research was presented in a paper to appear in a special issue of the Astronomy and Astrophysics journal on CoRoT, volume 506-1, 22 October 2009: "The CoRoT-7 planetary system: two orbiting Super-Earths", by D. Queloz et al.

The team is composed of D. Queloz, R. Alonso, C. Lovis, M. Mayor, F. Pepe, D. Segransan, and S. Udry (Observatoire de Genève, Switzerland), F. Bouchy, F. and G. Hébrard, G. (IAP, Paris, France), C. Moutou, M. Barbieri, P. Barge, M. Deleuil, L. Jorda, and A. Llebaria (Laboratoire d'Astrophysique de Marseille, France), A. Hatzes, D. Gandolfi, E. Guenther, M. Hartmann, and G. Wuchterl (Thüringer Landessternwarte Tautenburg, Germany), M. Auvergne, A. Baglin, D. Rouan, and J. Schneider (LESIA, CNRS, Observatoire de Paris, France), W. Benz (University of Bern, Switzerland), P. Bordé, A. Léger, and M. Ollivier (IAS, UMR 8617 CNRS, Université Paris-Sud, France), H. Deeg (Instituto de Astrofísica de Canarias, Spain), R. Dvorak (University of Vienna, Austria), A. Erikson and H. Rauer (DLR, Berlin, Germany), S. Ferraz Mello (IAG-Universidade de Sao Paulo, Brazil), M. Fridlund (European Space Agency, ESTEC, The Netherlands), M. Gillon and P. Magain (Université de Liège, Belgium), T. Guillot (Observatoire de la Côte d'Azur, CNRS UMR 6202, Nice France), H. Lammer (Austrian Academy of Sciences), T. Mazeh (Tel Aviv University, Israel), and M. Pätzold (Köln University, Germany).

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".

Links
Contacts

Didier Queloz
Geneva Observatory, Switzerland
Phone: +41 22 379 2477
E-mail:
didier.queloz@unige.ch

François Bouchy
IAP, Paris and OHP, St Michel l'Observatoire, France
Phone: 33 4 92 70 64 94
E-mail:
bouchy@iap.fr

Claire Moutou
Laboratoire d'Astrophysique de Marseille, France
Phone: +33 4 91 05 59 66
E-mail:
Claire.Moutou@oamp.fr

Artie Hatzes
Thüringer Landessternwarte Tautenburg, Germany
Phone: +49 36 42 78 63 55
Mobile: +49 (0)163 69 13 863
E-mail:
artie@tls-tautenburg.de


ESO La Silla - Paranal - ELT Press Officer: Henri Boffin - +49 89 3200 6222 - hbofin@eso.org
ESO Press Officer in Chile: Valeria Foncea - +56 2 463 3123 - vfoncea@eso.org

National contacts for the media: http://www.eso.org/public/outreach/eson/

Sophisticated telescope camera debuts with peek at nest of black holes

This is a near-infrared image of the galactic center of our Milky Way obtained the week of Sept. 6, 2009, by a newly installed University of Florida-built near-infrared camera and spectrometer. The instrument, called FLAMINGOS-2, captures heat-generated light just beyond the visible spectrum. In this image, a standard camera could capture the scattered blue stars in the foreground, but only a near-infrared camera could “see” the yellow and red stars because their visible light is blocked by clouds of gas and dust. This part of space also contains thousands of exotic black holes and neutron stars, objects UF astronomers plan to locate and identify using the instrument, FLAMINGOS-2. The cluster of bright stars near the center of the image surrounds a gargantuan black hole. FLAMINGOS-2 is also anticipated to become the first instrument to track the growth and evolution of this black hole over the past 4 billion years.

This is a near-infrared image of the Tarantula Nebula in the Large Magellanic Cloud, the largest satellite galaxy circling the Milky Way. This image reveals a huge cluster of young stars being born from a cloud of gas. The large concentration of massive young stars in the very center of the image is illuminating the surrounding hydrogen gas with ultraviolet light, creating the glowing red nebula in the image.

GAINESVILLE, Fla. — Less than two months after they inaugurated the world’s largest telescope, University of Florida astronomers have used one of the world’s most advanced telescopic instruments to gather images of the heavens.

A team led by astronomy professor Stephen Eikenberry late last week captured the first images of the cosmos ever made with a UF-designed and built camera/spectrometer affixed to the Gemini South telescope in Chile. The handful of “first light” images include a yellow and blue orb-like structure that depicts our Milky Way galaxy, home to thousands of black holes – including, at its core, a “supermassive” black hole thought to be as massive as 4 million suns put together.

“We plan to use this instrument to provide the first accurate tracking of the growth and evolution of this black hole over the last 4 billion years,” Eikenberry said.

Installation of the instrument, called FLAMINGOS-2, caps a seven-year, $5 million effort involving 30 UF scientists, engineers, students and staff. Once the instrument is scientifically tested — a process expected to last around six months — it will support a range of new science. Astronomers will use FLAMINGOS-2 (FLAMINGOS is short for the Florida Array Multi-object Imaging Grism Spectrometer) to hunt the universe’s first galaxies, view stars as they are being born, reveal black holes and investigate other phenomena.

“Achieving first light is a great achievement and important milestone,” said Nancy Levenson, deputy director of the Gemini Observatory.

The 8-meter Gemini South telescope in the Chilean Andes is one of only about a dozen 8- to 10-meter telescopes worldwide. All require technologically sophisticated instruments to interpret the light they gather. FLAMINGOS-2 “sees” near-infrared or heat-generated light beyond the range of human vision. It can reveal objects invisible to the eye, such as stars obscured by cosmic dust, or objects so far away they have next to no visible light.

The instrument joins other near-infrared imagers installed on other large telescopes. But it is unusual in its ability to also act as a spectrometer, dividing the light into its component wavelengths. Astronomers analyze these wavelengths to figure out what distant objects are made of, how hot or cold they are, their distance from Earth, and other qualities.

Uniquely, FLAMINGOS-2 can take spectra of up to 80 different objects simultaneously, speeding astronomers’ hunt for old galaxies, black holes or newly forming stars and planets.

“At a cost of $1 per second for operating the Gemini telescope, it will make a huge gain in the scientific productivity and efficiency of the observatory,” Eikenberry said. “What would take an entire year previously can now be done in four nights. This is a real game changer.”

Astronomers compete heavily for time on the world’s largest telescopes, often waiting months or years for the opportunity to make observations. Eikenberry said his FLAMINGOS-2 agreement with Gemini South entitles him to at least 25 nights of observations. He will use the time to contribute to three large studies, or surveys, of the sky headed by UF astronomers.
The first is aimed at learning more about the thousands of black holes and neutron stars at the Milky Way’s center. The second will probe the formation and evolution of galaxies across time, while the third will investigate the birth of new stars.

Levenson said the Gemini telescopes are well-known for their excellent image quality. With its wide large field of view and ability examine dozens of objects at once, FLAMINGOS-2 is a good match with the Gemini South telescope.

“The center of our Milky Way galaxy is a very dusty, very crowded environment, so infrared measurements and the ability to separate the fine details of the different stars and other objects are very important,” she said.

FLAMINGOS-2’s debut comes less than two months after UF astronomers helped inaugurate the Gran Telescopio Canarias, the world’s largest telescope, in Spain’s Canary Islands. UF, which owns a 5 percent share of the 10-meter telescope, is the only participating U.S. institution.
The Gemini Observatory is the lead sponsor of FLAMINGOS-2 and the source of the $5 million for design and construction. The original FLAMINGOS, a smaller prototype that pioneered the approach used successfully in the larger version, was designed and built by the late UF astronomy professor Richard Elston. Elston was at work on the early stages of FLAMINGOS-2 when he died of cancer in 2004 at age 43.

The Gemini Observatory, which operates twin 8-m telescopes located in Chile in Hawaii, is an international collaboration supported in part by the National Science Foundation.

Credits

Writer:
Aaron Hoover, ahoover@ufl.edu, 352-392-0186

Source:
Stephen Eikenberry, eiken@ufl.edu, 352-672-4249