Category: Astronomy

Image credit: Gemini
A timely discovery by American amateur astronomer Jay McNeil, followed immediately by observations at the Gemini Observatory, has provided a rare glimpse into the slow, yet violent birth of a star about 1,500 light-years away. The resulting findings reveal some of the strongest stellar winds ever detected around an embryonic Sun-like star.

McNeil?s find was completely serendipitous. He was surveying the sky in January from his backyard in rural Kentucky and taking electronic images through his 3-inch (8-centimeter) telescope. When he examined his work, he noticed a small glowing smudge of light in the constellation of Orion that wasn?t there before. ?I knew this part of the sky very well and I couldn?t believe what I was seeing,? said McNeil. Astronomers were alerted almost immediately, via the Internet, and quickly realized that he had come across something special.

?It is extremely rare that we have an opportunity to study an important event like this, where a newly born star erupts and sheds light on its otherwise dark stellar nursery,? said Gemini astronomer Dr. Colin Aspin. Dr. Aspin and Dr. Bo Reipurth, (of the University of Hawaii?s Institute for Astronomy), published the first paper on this object, now known as McNeil?s Nebula. Their work, based on observations using the Frederick C. Gillett Gemini North Telescope on Mauna Kea, is in press for Astrophysical Journal Letters.

?McNeil?s Nebula is allowing us to add another important piece to the puzzle of the long, protracted birth of a star,? said Reipurth. ?It has been more than thirty years since anything similar has been seen, so for the first time, we have an opportunity to study such an event with modern instrumentation like that available at Gemini.?

Detailed images and spectra of the stellar newborn, taken using the Gemini Near-Infrared Imager and Multi-Object Spectrograph, demonstrate that the star has brightened considerably. It is blasting gas away from itself at speeds of more than 600 kilometers per second (over 2000 times faster than a typical commercial airplane). The observations indicate the eruption was triggered by complex interactions in a rotating disk of gas and dust around the star. For reasons that are still not fully understood, the inner part of the disk begins to heat up, causing the gases to glow. At the same time, some gas funnels along magnetic field lines onto the surface of the star, creating very bright hot spots and causing the star to grow. The eruption also cleared out some of the dust and gas surrounding the young star, allowing light to escape and illuminate a cone-shaped cavity carved out by previous eruptions into the gas.

The birth of a star takes several tens of thousands of years and these observations are but a brief snapshot of the process. Although this is very a rapid schedule on astronomical time scales, Reipurth explained that it?s impossibly slow compared to a human lifetime. ?We astronomers therefore have no choice but to compare various objects where each one is in a different state of development,? he said. ?This is very similar to the imaginary situation of an alien landing on Earth with only half an hour to understand the full life cycle of humans. By looking at people of various ages and using some logic, this alien could piece together our growth from infant to old age. This is how we are beginning to understand the birth and youth of stars. Rare events like the one McNeil discovered help to fill in the blanks in our understanding of stellar origins.?

This outburst may not be the first time the star has flared during its long tumultuous birth. Following McNeil?s discovery, an inspection of archival plates revealed that a similar event took place in 1966, when the star flared and faded again into its enshrouding gas. ?We know so little about these kind of eruptions that we cannot even say whether the star will continue to flare or will rapidly fade from view again,? said Aspin. ?We were extremely fortunate that Mr. McNeil discovered this when he did. In an event like this, the earlier we can observe it, the better our chances are of understanding what is going on.?

Fortunately for Aspin and Reipurth, McNeil discovered this in the early winter while the Orion region is still high in the night-time sky. It was also fortunate that McNeil was so familiar with this part of the sky that he noticed right away that something had changed. This combination of circumstances enabled the astronomers to prepare an observation run on Gemini very quickly. ?Our window for observing this object is closing rapidly but it will become visible again later this year,? said Aspin. ?By then this eruption could be over.?

A striking color image from Gemini reveals fine details in McNeil?s Nebula. The star and its bright disk shine like a lighthouse through the cavity of gas and dust. The Gemini image and an artist?s conception of how the escaping gas and hotspots on a young star might have caused this event can be found here.

The Gemini Observatory is an international collaboration that has built two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai`i (Gemini North) and the Gemini South telescope is located on Cerro Pach?n in central Chile (Gemini South), and hence provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in each partner country with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the Canadian National Research Council (NRC), the Chilean Comisi?n Nacional de Investigaci?n Cientifica y Tecnol?gica (CONICYT), the Australian Research Council (ARC), the Argentinean Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) and the Brazilian Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq). The Observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

The Institute for Astronomy at the University of Hawaii conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea. Refer to http://www.ifa.hawaii.edu/ for more information about the Institute.

Original Source: Gemini Observatory News Release

Image credit: NASA/JPL
Like a busy urban family, planets rarely get together all at once. Later this month, however, the five so-called naked-eye planets – Mercury, Venus, Mars, Jupiter and Saturn – will reunite in the night sky, giving spectators a unique chance to see Earth’s closest companions in one easy sitting.

The gathering will be visible every night for an hour after sunset, beginning around March 22 and lasting about two weeks. While other opportunities to catch a five-planet rendezvous will take place in the next few years, both at dawn and dusk, this one is not to be missed.

“This particular planetary grouping will quite possibly offer the best nighttime views until 2036,” says Dr. Myles Standish, an astronomer at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

For early risers, there will be another chance to see all five naked-eye planets together just before sunrise in December of this year and early January 2005.

Since ancient times, the naked-eye planets have intrigued and inspired onlookers all over the world. But only sporadically, usually every few years or so, do their orbits take them to the same side of the Sun. When this happens, the planets stretch across the morning or evening skies depending on which side of the Sun they reside. More rare are planetary alignments in which the five planets assemble in a very small corner of the sky.

“Every so often the five visible planets will collect on one side of the Sun,” says Standish. “Only when conditions are right, will they all be clearly visible at either dusk or dawn.”

The Details
To catch the planetary get-together, you’ll need a good view of the sky, free of buildings and bright city lights (you should still be able to see the planets through urban light pollution). The show begins around March 22 and lasts through early April, when Mercury fades from sight. The finest views will take place during the last 8 to 10 days of March.

Begin by looking to the western horizon each evening just after sunset. Seated in a row up and across the sky will be Mercury, Venus, Mars and Saturn. Saturn will lie almost directly overhead. Following the line of the planets, Jupiter will be close to the eastern horizon. Together, the planets will span about 135 degrees. About an hour after dusk, Mercury will dip below the western horizon.

The Moon will also be attending the festivities, mingling through the planets in an orderly fashion. On March 22, it will take a seat next to Mercury, and then climbing up the night sky, it will end its tour on April 1 right above mighty Jupiter, the largest planet in our solar system. As the Moon slides from planet to planet, it will grow in size from a slender crescent to a nearly full circle of white.

Note that Venus is currently brighter than usual because of where it lies in relation to Earth and the Sun.

The Moon and planets will appear to follow nearly the same path through the stars. This is because their orbits around the Sun occupy planes that are close to that of Earth’s orbit. The plane Earth moves in is called the ecliptic.

If for some reason you miss the “Fab Five,” another set of orbiting bodies will soon make a grand debut. In April and May of this year, two naked-eye comets, C/2001 Q4 and C/2002 T7, will grace the twilight skies. To spot the cosmic balls of dust and ice look to the west at dusk or dawn. A pair of binoculars will help to initially locate the comets because they may be slightly washed out by the Sun. On May 12 to 16 look out for a mini-reunion with the naked-eye planets, when comet C/2001 Q4 lines up with Venus, Mars, Saturn and Jupiter.

Original Source: NASA/JPL News Release

Image credit: Sky and Telescope
For the next couple weeks, all five planets that are ever visible to the unaided eye shine at once during dusk. Moreover, the Moon and a prominent star cluster join the show as well, forming striking combinations in the early-evening sky.

“This is a special time for anyone who notices the sky,” says Alan MacRobert, a senior editor of Sky & Telescope magazine. “You don’t have to be any kind of great astronomer to enjoy this.”

Sky & Telescope offers news media the following guide to the changing celestial scenery. (All descriptions are for midnorthern latitudes, such as those in the United States and southern Canada.)

Every Evening, March 19?31: Spot All Five Planets
Look west as twilight fades on any clear evening, and there’s dazzling white Venus. You can’t miss it. Venus is the brightest point of light in the early-evening sky.

Look very far below Venus, and perhaps a bit to the right, to catch fainter little Mercury near the horizon. Be sure to look early (about 45 to 60 minutes after sunset) before Mercury gets too low and sets.

To the upper left of Venus, by roughly the width of your fist held at arm’s length, you’ll find fainter Mars, glimmering pale orange-red.

Three times farther to Mars’s upper left is pale yellow Saturn. It’s positioned high above the bright constellation Orion.

And Jupiter is the big, bright point of light shining high in the east-southeast. It’s second in brightness only to Venus.

One-Day Events
March 22: Crescent Moon and Mercury
Look low in the west (far below bright Venus) as twilight fades to pick up the beautifully thin crescent Moon. Look to its lower right ? and there’s Mercury. Binoculars give a fine view.

March 23: Moon under Venus
The crescent Moon shines below bright Venus in the west this evening, offering a foretaste of their beautiful conjunction (close pairing) tomorrow.

March 24: Crescent Moon and Venus Grab the Eye!
The Moon and Venus are closely paired in the western sky this evening, a strikingly beautiful sight. “This is going to be a real head-turner,” says MacRobert. “People will see this through their windshields driving home from work and say, ‘What’s that?'”

The Moon and Venus are the two brightest objects in the sky after the Sun. Binoculars will give an especially gorgeous view of them paired. This is also a good time to look for “earthshine” making the dark portion of the Moon glow dimly gray. Earthshine is sunlight reflected from the Earth onto the Moon’s nighttime landscape ? the same way a full Moon lights the ground on Earth at night.

As dusk deepens, look for fainter Mars to the upper left of the Moon and Venus, the star Aldebaran to the left or upper left of Mars (looking like its twin), and the Pleiades star cluster nearer to Mars’s right. The cluster is about as big as your fingertip held at arm’s length.

March 25: Moon with Mars
As a coda to yesterday’s Moon-Venus pairing, the Moon now pairs very closely with dimmer orange-red Mars ? while Venus blazes brightly to their lower right.

March 27: Saturn Left of the Moon
The Moon now pairs up with Saturn, the next planet east across the sky. Saturn is to the Moon’s left. Look below them for the bright constellation Orion.

March 28: Saturn under the Moon
Tonight you’ll find the pale yellow point of Saturn shining beneath the Moon, which is now at first-quarter phase (half lit).

April 1?4: Venus Meets the Pleiades
Meanwhile, action has been developing in the west. During and after nightfall in the first few days of April, you’ll see the little Pleiades star cluster positioned close to brilliant Venus. Again, binoculars give a wonderful view.

April 2: Moon Shines with Jupiter
Tonight the gibbous Moon shines close to bright Jupiter ? the last of the five naked-eye planets that it meets ? high in the southeast.

Original Source: S&T News Release

Image credit: ESA
ESA’s Integral gamma-ray observatory has resolved the diffuse glow of gamma rays in the centre of our Galaxy and has shown that most of it is produced by a hundred individual sources.

Integral’s high sensitivity and pointing precision have allowed it to detect these celestial objects where all other telescopes, for more than thirty years, had seen nothing but a mysterious, blurry fog of gamma rays…

During the spring and autumn of 2003, Integral observed the central regions of our Galaxy, collecting some of the perpetual glow of diffuse low-energy gamma rays that bathe the entire Galaxy.

These gamma rays were first discovered in the mid-1970s by high-flying balloon-borne experiments. Astronomers refer to them as the ‘soft’ Galactic gamma-ray background, with energies similar to those used in medical X-ray equipment.

Initially, astronomers believed that the glow was caused by interactions involving the atoms of the gas that pervades the Galaxy. Whilst this theory could explain the diffuse nature of the emission, since the gas is ubiquitous, it failed to match the observed power of the gamma rays. The gamma rays produced by the proposed mechanisms would be much weaker than those observed. The mystery has remained unanswered for decades.

Now Integral’s superb gamma-ray telescope IBIS, built for ESA by an international consortium led by Principal Investigator Pietro Ubertini (IAS/CNR, Rome, Italy), has seen clearly that, instead of a fog produced by the interstellar medium, most of the gamma-rays are coming from individual celestial objects. In the view of previous, less sensitive instruments, these objects appeared to merge together.

In a paper published today in Nature, Francois Lebrun (CEA Saclay, Gif sur Yvette, France) and his collaborators report the discovery of 91 gamma-ray sources towards the direction of the Galactic centre. Lebrun’s team includes Ubertini and seventeen other European scientists with long-standing experience in high-energy astrophysics. Much to the team’s surprise, almost half of these sources do not fall in any class of known gamma-ray objects. They probably represent a new population of gamma-ray emitters.

The first clues about a new class of gamma-ray objects came last October, when Integral discovered an intriguing gamma-ray source, known as IGRJ16318-4848. The data from Integral and ESA’s other high-energy observatory XMM-Newton suggested that this object is a binary system, probably including a black hole or neutron star, embedded in a thick cocoon of cold gas and dust. When gas from the companion star is accelerated and swallowed by the black hole, energy is released at all wavelengths, mostly in the gamma rays.

However, Lebrun is cautious to draw premature conclusions about the sources detected in the Galactic centre. Other interpretations are also possible that do not involve black holes. For instance, these objects could be the remains of exploded stars that are being energised by rapidly rotating celestial ‘powerhouses’, known as pulsars.

Observations with another Integral instrument (SPI, the Spectrometer on Integral) could provide Lebrun and his team with more information on the nature of these sources. SPI measures the energy of incoming gamma rays with extraordinary accuracy and allows scientist to gain a better understanding of the physical mechanisms that generate them.

However, regardless of the precise nature of these gamma-ray sources, Integral’s observations have convincingly shown that the energy output from these new objects accounts for almost ninety per cent of the soft gamma-ray background coming from the centre of the Galaxy. This result raises the tantalising possibility that objects of this type hide everywhere in the Galaxy, not just in its centre.

Again, Lebrun is cautious, saying, “It is tempting to think that we can simply extrapolate our results to the entire Galaxy. However, we have only looked towards its centre and that is a peculiar place compared to the rest.”

Next on Integral’s list of things to do is to extend this work to the rest of the Galaxy. Christoph Winkler, ESA’s Integral Project Scientist, says, “We now have to work on the whole disc region of the Galaxy. This will be a tough and long job for Integral. But at the end, the reward will be an exhaustive inventory of the most energetic celestial objects in the Galaxy.”

Original Source: ESA News Release

Image credit: SDSS
One of the largest astronomy catalogs ever compiled was released to the public today by the Sloan Digital Sky Survey (SDSS).

With photometric and spectroscopic observations of the sky gathered during the last two years, this second data release (DR2) offers six terabytes of images and catalogs, including two terabytes in an easy to use searchable database.

This public data release provides digital images and measured properties of more than 88 million celestial objects, as well as spectra and redshifts of over 350,000 objects. The data are available from the SDSS Web site (http://www.sdss.org/DR2) or from the SkyServer Web site more attuned to the general public (http://skyserver.sdss.org/).

The SDSS is the most ambitious astronomical survey ever undertaken. A consortium of more than 200 astronomers at 13 institutions around the world, the SDSS will map in detail one-quarter of the entire sky, determining the positions and brightnesses of several hundred million celestial objects. It will also measure the distances to approximately one million galaxies and quasars.

“Getting DR2 out to the broader astronomical community and to the general public will allow these data to be analyzed for projects limited only by the imagination and ingenuity of the user,” said Michael Strauss of Princeton University, scientific spokesperson for the SDSS.

Strauss explained that while members of the SDSS international collaboration have written more than 200 scientific papers with SDSS data, “we feel we’ve barely started. There is far more interesting science to be done and discoveries to be made with these data than we have time or people to do. This is why this data release is so important.” Public searchable data in the survey have doubled from June 2003 to today.

“Many external researchers are already using the data from earlier public releases”, explained Alex Szalay of the Johns Hopkins University, an architect of the SDSS’s data mining tools. In fact, researchers from outside of the consortium wrote roughly half of the SDSS-related papers presented at recent American Astronomical Society meetings. “This is a clear indication that we’ve kept our promise to the scientific community of getting them uniformly high quality data in a timely manner and in a searchable format.”

The first public data release from the SDSS in 2003 contained information on 50 million objects, including spectra and redshifts for almost 200,000 of these objects. The SDSS is an ongoing survey that recorded its first observations in May 1998 and is funded for operations through Summer 2005.

The 2.5-meter SDSS telescope is located at Apache Point Observatory in New Mexico and is operated by the Astrophysical Research Consortium. The telescope has two main instruments: an imaging camera, one of the largest ever built, and a spectrograph capable of recording data from 640 objects at a time. The camera creates images from digital scans through five filters: ultraviolet, green, red, and two infrared bands.

CATALOG OF RESULTS
Scientific findings and ground-breaking discoveries already achieved with the DR2 data from the most distant quasars, to the coolest stars, the properties of galaxies to the sizes of asteroids, the structure of the halo of our Milky Way and the large-scale structure of the universe.

DR2 consists of images from 3,324 square degrees of the Northern sky and more than 88 million galaxies, stars, and quasars. The survey is complete for objects as faint as 22.2 magnitude, three million times fainter than the faintest star that can be seen with the naked eye on a dark night.

In addition to images from the SDSS telescope, the DR2 includes the spectra, and therefore redshifts, of 260,000 galaxies, 36,000 quasars, and 48,000 stars, according to consortium member Mark Subbarao of the University of Chicago. The galaxy and quasar catalogs are the largest ever produced.

SEARCH REFINEMENTS
Jim Gray of Microsoft Corp. was part of the team working to make the observations accessible to the astronomical community and the public. The team developed several algorithms to efficiently search the complicated database.

“The SDSS is a BIG database with researchers making very complicated queries for spatial, color and space parameters,” explained Gray, a distinguished engineer in Microsoft’s Scaleable Servers Research Group and manager of Microsoft’s Bay Area Research Center.

“It has been very rewarding working with the SDSS. The people are very creative, enthusiastic, and bright. The SDSS has shown that we database folks need to do a better job in many ways,” Gray said. “For Microsoft, the SkyServer and Catalog Archive Server are an information-at-your-fingertips project we’ve helped develop for astronomers. I see them as archetypes of what all the sciences need.”

Ani Thakar, an SDSS astronomer from the Johns Hopkins University’s Center for Astrophysical Sciences, who has worked closely with Szalay and Gray on the SkyServer, said the DR2 database has a form-based Web page for imaging and spectroscopic queries.

“This gives astronomers the ability to extract detailed information from the database without having to learn a query language. We’ve also added a batch service that lets users submit queries that are likely to take a long time. They can come back later and pick up the results,” Thakar explained.

DR2 also offers enhanced querying and filtering options like image cutout and finding chart services. Users can cross-identify objects by uploading lists of object positions on the sky.

The SDSS anticipates releasing more data in its ongoing celestial census late this year.

Original Source: SDSS News Release

Image credit: NASA/JPL
NASA-funded researchers have discovered the most distant object orbiting Earth’s Sun. The object is a mysterious planet-like body three times farther from Earth than Pluto.

“The Sun appears so small from that distance that you could completely block it out with the head of a pin,” said Dr. Mike Brown, California Institute of Technology, Pasadena, Calif., associate professor of planetary astronomy and leader of the research team. The object, called “Sedna” for the Inuit goddess of the ocean, is 13 billion kilometers (8 billion miles) away, in the farthest reaches of the solar system.

This is likely the first detection of the long-hypothesized “Oort cloud,” a faraway repository of small icy bodies that supplies the comets that streak by Earth. Other notable features of Sedna include its size and reddish color. After Mars, it is the second reddest object in the solar system. It is estimated Sedna is approximately three-fourths the size of Pluto. Sedna is likely the largest object found in the solar system since Pluto was discovered in 1930.

Brown, along with Drs. Chad Trujillo of the Gemini Observatory, Hawaii, and David Rabinowitz of Yale University, New Haven, Conn., found the planet-like object, or planetoid, on Nov. 14, 2003. The researchers used the 48-inch Samuel Oschin Telescope at Caltech’s Palomar Observatory near San Diego. Within days, telescopes in Chile, Spain, Arizona and Hawaii observed the object. NASA’s new Spitzer Space Telescope also looked for it.

Sedna is extremely far from the Sun, in the coldest know region of our solar system, where temperatures never rise above minus 240 degrees Celsius (minus 400 degrees Fahrenheit). The planetoid is usually even colder, because it approaches the Sun only briefly during its 10,500-year solar orbit. At its most distant, Sedna is 130 billion kilometers (84 billion miles) from the Sun, which is 900 times Earth’s solar distance.

Scientists used the fact that even the Spitzer telescope was unable to detect the heat of the extremely distant, cold object to determine it must be less than 1,700 kilometers (about 1,000 miles) in diameter, which is smaller than Pluto. By combining available data, Brown estimated Sedna’s size at about halfway between Pluto and Quaoar, the planetoid discovered by the same team in 2002.

The elliptical orbit of Sedna is unlike anything previously seen by astronomers. However, it resembles that of objects predicted to lie in the hypothetical Oort cloud. The cloud is thought to explain the existence of certain comets. It is believed to surround the Sun and extend outward halfway to the star closest to the Sun. But Sedna is 10 times closer than the predicted distance of the Oort cloud. Brown said this “inner Oort cloud” may have been formed by gravity from a rogue star near the Sun in the solar system’s early days.

“The star would have been close enough to be brighter than the full moon, and it would have been visible in the daytime sky for 20,000 years,” Brown explained. Worse, it would have dislodged comets farther out in the Oort cloud, leading to an intense comet shower that could have wiped out some or all forms of life that existed on Earth at the time.

Rabinowitz said there is indirect evidence that Sedna may have a moon. The researchers hope to check this possibility with NASA’s Hubble Space Telescope. Trujillo has begun to examine the object’s surface with one of the world’s largest optical/infrared telescopes, the 8-meter (26-foot) Frederick C. Gillett Gemini Telescope on Mauna Kea, Hawaii. “We still don’t understand what is on the surface of this body. It is nothing like what we would have predicted or what we can explain,” he said.

Sedna will become closer and brighter over the next 72 years, before it begins its 10,500-year trip to the far reaches of the solar system. “The last time Sedna was this close to the Sun, Earth was just coming out of the last ice age. The next time it comes back, the world might again be a completely different place,” Brown said.

NASA’s Jet Propulsion Laboratory, Pasadena, Calif, manages the Spitzer Space Telescope. For more information about the research and images on the Internet, visit http://www.spitzer.caltech.edu/Media/releases/ssc2004-05. For information about NASA on the Internet, visit http://www.nasa.gov.

Original Source: NASA/JPL News Release

Image credit: Caltech
The California Institute of Technology and Cornell University are in the planning stages for a new 25-meter telescope to be built in Chile. The submillimeter telescope will cost an estimated $60 million and will be nearly two times larger in diameter than the largest submillimeter telescope currently in existence.

The first step of the plan, which is being announced today jointly by Caltech and Cornell, commits the two institutions to a $2-million study, says Jonas Zmuidzinas, a physics professor at Caltech who is leading the Institute’s part of the collaboration. The telescope is projected for a 2012 completion date on a high site in the Atacama Desert of northern Chile, and will significantly ramp up Caltech’s research in submillimeter astronomy.

Scientists from Cornell, Caltech, and Caltech’s Jet Propulsion Laboratory (JPL) will be participating in the telescope study, including Caltech faculty members Andrew Blain, Sunil Golwala, Andrew Lange, Tom Phillips, Anthony Readhead, Anneila Sargent, and others.

“We are very much looking forward to working with our Cornell colleagues on this project,” says Zmuidzinas.

At Cornell, the participants will include professors Riccardo Giovanelli, Terry Herter, Gordon Stacey, and Bob Brown.

Submillimeter wavelength astronomy allows the study of a number of astrophysical phenomena that do not emit much visible or infrared light. The new telescope will observe stars and planets forming from swirling disks of gas and dust, will make measurements to determine the composition of the molecular clouds from which the stars are born, and could even discover large numbers of galaxies undergoing huge bursts of star formation in the very distant universe.

Also, the 25-meter telescope could be used to study the origin of large-scale structure in the universe.

“So far, we have gotten just a small taste of what there is to learn at submillimeter wavelengths,” says Zmuidzinas. “This telescope will be a huge step forward for the field.”

The new telescope is poised to take advantage of the rapid development of sensitive superconducting detectors, an area in which Zmuidzinas and his Caltech/JPL colleagues have been making important contributions. The new superconducting detectors enable large submillimeter cameras to be built, which will produce very sensitive panoramic images of the submillimeter sky.

The 25-meter telescope is a natural progression in Caltech and JPL’s longstanding interest in submillimeter astronomy. Caltech already operates the Caltech Submillimeter Observatory (CSO), a 10.4-meter telescope constructed and operated with funding from the National Science Foundation, with Tom Phillips serving as director. The telescope is fitted with sensitive submillimeter detectors and cameras, many of which were developed in collaboration with JPL, making it ideal for seeking out and observing the diffuse gases and their constituent molecules, crucial to understanding star formation.

The advantages of the new telescope will be fourfold. First, due to the larger size of its mirror and its more accurate surface, the 25-meter telscope should provide six to 12 times the light-gathering ability of the CSO, depending on the exact wavelength. Second, the larger diameter and better surface will result in much sharper images of the sky. Third, the large new cameras will provide huge advantages over those currently available.

Finally, the 16,500-foot elevation of the Atacama Desert will provide an especially dry sky for maximum effectiveness. Submillimeter wavelengths (as short as two-tenths of a millimeter) are strongly absorbed by the water vapor in the atmosphere. For maximum effectiveness, a submillimeter telescope must be located at a very high, very dry altitude–the higher the better–or best of all, in space.

However, while the idea of a large (10-meter) submillimeter telescope in space is being considered by NASA and JPL, it is still more than a decade away. Meanwhile, existing space telescopes such as the Hubble and the Spitzer work at shorter wavelengths, in the visible and infrared, respectively.

In 2007, the European Space Agency plans to launch the 3.5-meter Herschel Space Observatory, which will be the first general-purpose submillimeter observatory in space. NASA is participating in this project, and scientists at JPL and Caltech are providing detectors and components for the science instruments.

“It is a very exciting time for submillimeter astronomy,” says Zmuidzinas. “We are making rapid progress on all fronts–in detectors, instruments, and new facilities–and this is leading to important scientific discoveries.”

Original Source: Caltech News Release

Image credit: Spitzer
In a small nearby galaxy lies a luminous cloud of gas and dust, called a nebula, which houses a family of newborn stars. If not for the death of a massive star millions of years ago, this stellar nursery never would have formed.

The nebula, Henize 206, and the remnants of the exploding star that created it, are pictured in superb detail in a new image from NASA’s Spitzer Space Telescope. Henize 206 sits just outside our own galaxy, the Milky Way, in a satellite galaxy 163,000 light-years away called the Large Magellanic Cloud. It is home to hundreds and possibly thousands of stars, ranging in age from two to 10 million years old.

“The image is a wonderful example of the cycle of birth and death that gives rise to stars throughout the universe,” said Dr. Varoujan Gorjian, a scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., and principal investigator for the latest observation.

As in other stellar nurseries, the stars in Henize 206 were created when a dying star, or supernova, exploded, shooting shock waves through clouds of cosmic gas and dust. The gas and dust were subsequently compressed, gravity kicked in, and stars were born. Eventually, some of the stars will die in a fiery blast, triggering another cycle of birth and death. This recycling of stellar dust and gas occurs across the universe. Earth’s own Sun descended from multiple generations of stars.

The new Spitzer picture provides a detailed snapshot of this universal phenomenon. By imaging Henize 206 in the infrared, Spitzer was able to see through blankets of dust that dominate visible light views. The resulting false-color image shows embedded young stars as bright white spots, and surrounding gas and dust in blue, green and red. Also revealed is a ring of green gas, which is the wake of the ancient supernova’s explosion.

“Before Spitzer, we were only seeing tantalizing hints of the newborn stars peeking through shrouds of dust,” Gorjian said.

These observations provide astronomers with a laboratory for understanding the early universe, and stellar birth and death cycles. Unlike large galaxies, the Large Magellanic Cloud has a quirk. The gas permeating it contains roughly 20 to 50 percent of the heavier elements, such as iron, possessed by the Sun and gas clouds in the Milky Way. This low-metallicity state approximates the early universe, allowing astronomers to catch a glimpse of what stellar life was like billions of years ago, when heavy metals were scarce.

Henize 206 was first catalogued in the early 1950s by Dr. Karl Henize (pronounced Hen-eyes), an astronomer who became a NASA astronaut. He flew aboard the Challenger Space Shuttle in 1985. He died in 1993 at age 66 while climbing Mount Everest.

Launched on August 25, 2003, from Cape Canaveral, Fla., the Spitzer Space Telescope is the fourth of NASA’s Great Observatories. The program includes the Hubble Space Telescope, Chandra X-ray Observatory and Compton Gamma Ray Observatory. JPL manages the Spitzer Space Telescope mission for NASA’s Office of Space Science, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena, which manages JPL.

For information about NASA and agency exploration programs on the Internet, visit http://www.nasa.gov. The Spitzer picture is available at http://www.spitzer.caltech.edu and http://photojournal.jpl.nasa.gov. For information about the Spitzer Space Telescope, visit http://www.spitzer.caltech.edu.

Original Source: NASA News Release

Image credit: RAS
Using a British radio telescope called the Very Small Array (VSA), located on the flanks of Mount Teide in Tenerife, astronomers from the Universities of Manchester and Cambridge and the Instituto de Astrofisica de Canarias (IAC) have made measurements of the Cosmic Microwave Background (CMB) – radiation left over from the Big Bang – which shed new light on events in the first minute fraction of the Universe’s existence.

By combining their results with those of NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) satellite, they have been able to constrain the behaviour of the Universe during the ‘inflationary’ phase believed to have taken place when it was only 10(-35) seconds old. If confirmed, these results will significantly challenge our current views of inflation and the first moments of creation.

Dr. Richard Davis of Jodrell Bank Observatory, University of Manchester, who was involved in the design and building of the VSA and leads the Jodrell Bank team, said, “From the holiday island of Tenerife we have probed the first moment of creation, when the Universe was a million-million-millionth of the size of the atom. Using this British-funded instrument, we see echoes of the crazy expansion which took place in the early Universe; it is quite incredible!”

The idea of inflation is that the Universe expanded extremely quickly during its very early existence, creating a Universe whose properties are very uniform on the largest scales. However Quantum Mechanics, the theory of the sub-atomic world, would have created minute fluctuations in the density of the early Universe which eventually led to the formation of galaxies such as our own Milky Way. These fluctuations also imprinted minute temperature variations on the observed CMB, so allowing them to be studied by extremely sensitive instruments such as the VSA.

The Quantum Mechanical fluctuations produced variations in density and temperature over a very wide range of scale sizes. The finer detail of the VSA observations, as compared with those of WMAP, has enabled a better understanding of how the distribution of these fluctuations varies as a function of size.

Previous ideas had suggested that, once the subsequent history of the Universe is accounted for, the distribution of fluctuations would be independent of scale. However, the current results show that the fluctuations are most apparent at an angular scale of about 1/2 degree, the size of the Moon in the night sky. On both larger (the size of the Universe) and smaller (the size of a cluster of galaxies) scales, these variations in density and temperature are much less.

“The most popular inflation models predict much smaller variations than those seen in the new observations,” said Dr. Richard Battye (Jodrell Bank Observatory), who was involved in the analysis and interpretation of the data. “The increasing sensitivity of instruments such as the VSA is enabling us to test these inflation models. The results are not totally conclusive at this stage, but if true they will require a complete re-think of the prevailing view of the first moments of creation.”

The results from the VSA have been confirmed by a concurrent experiment, the Cosmic Background Imager (CBI), which is located high in the Chilean Andes and operated by the California Institute of Technology. The results at this stage are highly suggestive, but it is hoped that further measurements by the VSA, CBI and eventually the PLANCK satellite, will allow more definitive conclusions to be drawn. PLANCK, which is due to be launched by the European Space Agency in 2007, will employ highly sensitive receivers built by engineers at the Jodrell Bank Observatory.

Two papers detailing these results have been submitted to the Monthly Notices of the Royal Astronomical Society.

Original Source: RAS News Release

Image credit: UC Berkeley
University of California, Berkeley, astronomers have taken advantage of a recently mounted laser guide star system at UC’s Lick Observatory to obtain sharp, twinkle-free images of the faint dusty disks of distant massive stars. The images clearly show that stars two to three times larger than the sun form in the same way as solar-type stars – inside a swirling spherical cloud that collapses into a disk, like that from which the sun and its planets emerged.

The yellow laser beam piercing the heavens over Lick Observatory became operational on the 10-foot Shane telescope last year, expanding use of the telescope’s “rubber mirror” system, called adaptive optics, to the entire nighttime sky. The addition of the laser makes Lick the only observatory to provide a laser guide star for routine use.

The UC Berkeley team and its colleagues at UC Santa Cruz’s Center for Adaptive Optics and Lawrence Livermore National Laboratory (LLNL) report their results in the Feb. 27 issue of the journal Science.

“The paradigm for stars like our sun is gravitational collapse of a cloud to a protostar and a pancake-like accretion disk, but there’s some mass at which this can’t work – the luminosity of the star becomes sufficient to disrupt the disk, and it falls apart as fast as it pulls together,” said James R. Graham, professor of astronomy at UC Berkeley. “Our data show that the standard model paradigm still works for stars two to three times as massive as the sun.”

“Without adaptive optics, we’d see only a big fuzzy blob from the ground and would be unable to detect any of the fine structure around the sources,” added UC Berkeley graduate student Marshall D. Perrin. “Our observations provide strong support for an emerging view that low and intermediate mass stars form in a similar manner.”

An adaptive optics system, which removes the blurring effects of atmospheric turbulence, was added to Lick’s Shane telescope in 1996. However, like all other telescopes with adaptive optics today, including the twin 10-meter Keck Telescopes in Hawaii, the Lick telescope has had to rely upon bright stars in the field of view to provide the reference needed to remove the blur. Only about one to 10 percent of the objects in the sky are sufficiently near a bright star for such a “natural” guide star system to work.

The sodium dye laser, developed by ace laser scientists Deanna M. Pennington and Herbert Friedman of LLNL, finally completes the adaptive optics system so that astronomers can use it to view any part of the sky, whether or not a bright star is nearby.

Strapped to the bore of the Lick telescope, the laser shines a narrow beam about 60 miles through the turbulent zone into the upper atmosphere, where the laser light stimulates sodium atoms to absorb and re-emit light of the same color. The sodium comes from micrometeorites that flame out and evaporate as they enter the Earth’s atmosphere.

The yellow glowing spot created in the atmosphere is equivalent to a 9th magnitude star – about 40 times fainter than the human eye can see. Nevertheless, it provides a steady light source just as effective as a bright distant star.

“We use that light to measure the turbulence in the atmosphere over our telescope hundreds of times per second, and then use that info to shape a special flexible mirror in such a way that when the light, both from the laser and the target you are looking at, bounces off it, the effects of the turbulence are removed,” said Claire Max, a professor of astronomy and astrophysics at UC Santa Cruz, deputy director of the Center for Adaptive Optics and a researcher at LLNL who has been working for more than 10 years to develop a laser guide star system.

In one of the first tests of this system, Graham and Perrin turned the telescope on rare, young, massive stars called Herbig Ae/Be stars that are fuzzy from the ground and typically too faint to be imaged by natural guide star adaptive optics. Herbig Ae/Be stars, with masses between 1.5 and 10 times that of the sun and probably less than 10 million years old, are thought to be the beginnings of massive stars – stars that will end up like the hot, Type A stars Sirius and Vega. Herbig Ae/Be stars were cataloged years ago by UC Santa Cruz astronomer George Herbig, now at the University of Hawaii.

The most massive of the Herbig Ae/Be stars are of great interest because they are the ones that undergo supernova explosions that seed the galaxy with heavy atoms, making solid planets and even life possible. They also trigger star formation in nearby clouds.

What the astronomers saw was very similar to the known picture of T Tauri stars, which are the formative stages of stars up to 50 percent bigger than our sun and up to 100 million years old. Images of the two Herbig Ae/Be stars clearly show a dark line bisecting each star, caused by a disk blocking the star’s bright glare, and a glowing spherical halo of dust and gas enveloping the star and disk. In each star, two jets of gas and dust can be seem emerging from the poles of the accretion disk.

The two stars, catalogued as LkH( 198 and LkH( 233 (Lick hydrogen-alpha sources), are 2,000 and 3,400 light years away, respectively, in a distant region of the Milky Way galaxy.

“Material from the protostellar cloud cannot fall directly into the infant star, so it first lands in an accretion disk and only moves inward to fall onto the star after it has shed its angular momentum,” Perrin explained. “That process of angular momentum transfer, along with the evolution of magnetic fields, leads to the launching of the bipolar outflows. These outflows eventually clear away the envelope, leaving a newborn star surrounded by an accretion disk. Over a few million years, the rest of the material in the disk is accreted, leaving only the young star behind.”

Perrin added that the Hubble Space Telescope has provided “very clear-cut, unambiguous images of disks and outflows around T Tauri stars,” confirming theories about the formation of stars like our sun. But, due to the relative rarity of Herbig Ae/Be stars, such clear data for those stars has been lacking until now, he said.

Astronomers have proposed that very massive stars form from the collision of two or more stars, or in a turbulent cloud unlike the swirling accretion disk. Interestingly, a third star imaged the same night by Graham and Perrin turned out to be two sun-like stars with a ribbon of gas and dust between them, looking suspiciously like one star capturing matter from the other.

Graham hopes to photograph more massive Herbig Ae/Be stars to see if the standard star formation model extends to even larger stars. The detailed images of the Herbig Ae/Be stars owe as much to the new laser guide star system as to a near-infrared imaging polarimeter built by Perrin and added to the Berkeley Near Infrared Camera (IRCAL) already mounted on the telescope.

“Without a polarimeter, light from the stars largely obscures the structures around them,” Perrin said. “The polarimeter separates unpolarized starlight from polarized scattered light from the circumstellar dust, which increases the detectability of that dust. Now that we’ve developed this technique at Lick, it will be possible to extend it to the 10-meter Keck telescopes as the laser guide star system there becomes operational.”

The polarimeter splits the light from the image into its two polarizations using a new type of birefringent crystal made of lithium, yttrium and fluorine (LiYF4), an improvement over the calcite crystals used to date.
Many other groups are developing lasers to be used as guide stars, but Max’s group has been ahead of its competitors since first demonstrating the concept in the early 1990s at Livermore. Since then, she and colleagues have been perfecting the laser and the software that allows the mirror – in the case of Lick’s 120-inch telescope, a 3-inch secondary mirror inside the main telescope – to be flexed just right to remove the twinkle from stars.

The 11- to 12-watt laser is a sodium dye laser tuned to the frequency that will excite the cold sodium atoms in the atmosphere. The dye laser is pumped by a green neodymium YAG laser, a bigger brother to the readily available green milliwatt laser pointers.

“The reason we can now do science with the laser guide star system is that its reliability and usability is so much improved,” Graham said. “The laser opens up adaptive optics to a much larger community.”

“I think it’s going to be a workhorse instrument at Lick,” added Max. “The laser itself and adaptive optics system hardware are pretty stable and pretty robust. What’s going to happen now is that people are going to do astronomy with it, they’re going to develop new techniques to observe with it, try it on new types of objects. In the typical way, a good astronomer will come and do things with your instrument that you never imagined.”

Max and her colleagues have tested an identical laser guide star system at the Keck Telescopes in Hawaii, but it is not yet ready for routine use, she said.
“The Keck is using the same technology we have at Lick,” Max said. “I expect to see this general technology used on most telescopes, but with different kinds of lasers. People are inventing new types of lasers right and left, so I think that game remains to settle out.”

Other authors of the Science paper, aside from Graham, Perrin, Max and Pennington, are affiliated with the National Science Foundation’s Center for Adaptive Optics, centered at UC Santa Cruz: assistant research astronomer Paul Kalas of UC Berkeley, James P. Lloyd of the California Institute of Technology, Donald T. Gavel of UC Santa Cruz’s Laboratory for Adaptive Optics, and Elinor L. Gates of the UC Observatories/Lick Observatory.

The observations and development of the laser guide star were funded by the National Science Foundation and the U.S. Department of Energy.

Original Source: UC Berkeley News Release