WISE “First Light” Image Released

WISE First Light image. Image credit: NASA/JPL-Caltech/UCLA

Caption: WISE First Light image. Image credit: NASA/JPL-Caltech/UCLA

“In many respects, the most important moment for a telescope is its first light,” said Bill Irace, project manager for the Wide-field Infrared Survey Explorer (WISE) spacecraft, speaking at the 215th American Astronomical Society meeting. “And we are happy to be able to share WISE’s first light image with you today.” The image covers a patch of sky about three times larger than the full moon. An interstellar dust cloud shows in the upper left, and the bright object in the right-center is V 482 Carina, an old puffy, cool giant star. The image was taken with what will be WISE’s standard 8.8 seconds of exposure time where it “stares” at a specific point in the sky. Ultimately, WISE will take millions of images to conduct an all sky survey in 10 months, before the frozen hydrogen that keeps the instrument cold evaporates away.

The exposure shows infrared light from three of WISE’s four wavelength bands: Blue, green and red correspond to 3.4, 4.6, and 12 microns, respectively. WISE will search for millions of hidden objects, including asteroids, “failed” stars, powerful galaxies and brown dwarf stars too cool to emit light, including a potential brown dwarf that might be closer to Earth than Proxima Centauri. WISE data will also serve as navigation charts for other missions.

Irace and David Leisawitz from Goddard Space Flight Center said in about a month, the science team will release the first images from the first survey to the public. “Longer term, the astronomical community around the world has been looking forward to this,” said Leisawitz, “as all of WISE’s data will be released for anyone to use starting in April 2011, with the final release in March 2012. The data products include an atlas of images and catalog of individual objects.”

Leisawitz said that magnificently and stunningly, WISE provides 400 times better angular resolution than the infrared instrument on the COBE spacecraft.

Irace divulged that this image was strictly an engineering image with no regard to the field of view. “We actually took about six images, but this one was the prettiest,” he said. “We did not point at a particular point in the sky, and in fact we didn’t know if we were going to be able to do it this fast, so this is basically a random image.”

The science team believes the spacecraft will still be operational for 3 additional months following the 10 month prime mission, and are writing a proposal to NASA for funding to continue.

For a larger version of the image, visit this NASA webpage.

Source: AAS press conference

New Studies on the Vela Star Forming Region

A false-color infrared image of the star forming complex in Vela. Two new studies have measured for the first time the dust emission at very long infrared wavelengths, and found a set of young stars that are accreting material and flaring. Credit: NASA and the Spitzer Space Telescope
A false-color infrared image of the star forming complex in Vela. Two new studies have measured for the first time the dust emission at very long infrared wavelengths, and found a set of young stars that are accreting material and flaring. Credit: NASA and the Spitzer Space Telescope

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This week at the AAS meeting scientists revealed two new studies on a star forming region in Vela. The first used the Balloon-borned Large Aperture Submillimeter Telescope (BLAST, a proptotype detector for the one on the new Herschel Space Telescope) to classify the young stars and begin mapping the warm dust in the region. The second searched the nebula for flaring young stars. Both studies are to appear in an upcoming publication of the Astrophysical Journal.

Although star formation has been well modeled and understood theoretically, observational astronomy is often made more difficult due to the fact that it occurs shrouded in dusty nebulae. Visible light absorbed by the nebula and reemitted as lower energy infrared light. Most of the wavelengths in this region cannot permeate Earth’s atmosphere.

In order to study regions like this, astronomers are forced to use balloon based and space observatories. Astronomers Massimo Marengo, Giovanni Fazio, and Howard Smith, together with an international team of scientists used BLAST to study just such a star forming region in Vela. The first of their studies searched the nebula for newly formed stars. To do this, they searched for behaviors shown to be indicative of star formation, “such as proto-stellar jets and molecular outflows.” Additionally, to truly classify as a proto-star, the object was required to show up at more than one wavelength. In searching for these candidates, they confirmed 13 cores originally reported by a previous team, but discounted one because it did not have the proper spectral characteristics (although they may still later collapse to form stars).

By analyzing the mass of the forming regions, the team was also able to show that the Core Mass Function (CMF, a function that describes the frequencies of proto-star cores of various masses) is very similar to the Initial Mass Function (IMF, which is the same thing but for already formed stars). Although this is unsurprising, it is a necessary observation to confirm our understanding of how stars form and to show that stars do indeed come from such nebulae.

Another unsurprising confirmation of stellar formation models is that forming cores in the nebula are notably warmer when they’ve reached the density sufficient to create fusion in the core and have an embedded protostar. These results, “can thus provide guidelines
for understanding the physical conditions where the transition between pre- and proto-stellar cores takes place.”

The second of their studies analyzed known young stars to search for large flares thought to be caused by material being accreted onto the young star. The region was imaged once and then a second time six months later. Over this period, 47 of some 170,000 observed stars had increases in brightness consistent with what was expected for flaring. Closer inspection of these stars 19 had the further characteristics (mass, age, environment) expected of such flares. Eight showed evidence of being extremely young (on the order of a hundred thousand years or less) and were still enshrouded in gravitationally bound disks of dust.

Although this cannot confirm the prediction of such youthful flares being due to infalling material (as opposed to magnetic fields or interactions with a companion) it does show that BLAST and its successor, Herschel, will be a powerful tool for further study.

First Science Results in from Herschel Telescope

Herschel looks deep inside the heart of a dark cloud located 1000 light years away in the constellation Aquila, the Eagle.Credit: ESA and the SPIRE and PACS consortia

The science teams from the Herchel telescope are meeting this week to discuss their first results from the intial months of observations by the newest infrared space telescope, which was launched in May. While details of the scientific findings won’t be released until Friday after everyone at the meetings has had a chance to share their results, ESA released a few stunning new pictures to give everyone a sample of what is to come. In addition to the images shown here, hints of other upcoming images include the most distant known quasar, a dwarf planet, and water sublimating from a comet’s surface. Some of the images have been described as among the most important images obtained from space for decades.

Above, Herschel peered deep inside an unseen stellar nursery in located 1000 light years away in the constellation Aquila, the Eagle, revealing a surprising amounts of activity. Some 700 newly-forming stars are estimated to be crowded into filaments of dust stretching through the image. The image is the first new release of ‘OSHI’, ESA’s Online Showcase of Herschel Images.

Herschel's look at the Southern Cross. Credits: ESA and the PACS consortium
Herschel's look at the Southern Cross. Credits: ESA and the PACS consortium

Another images release of the Southern Cross shows that even the darkest patches of sky can shine brightly to Herschel. Usually, this region looks like a bland cloud of dust, but Herschel shows it to be a place of intense star formation with filaments and condensations of dust cocooning newly forming stars. The dust forms into clumps along magnetic lines – like pearls on a necklace. Each clump is a very early star – at its embryonic stage.

The third image is of the spiral galaxy M51, also known as the Whirlpool Galaxy, showing off its spectacular infrared colors. Two huge waves of star formation encircle its central nucleus, making beautiful spiral arms. Each one shines brightly with its dust being warmed by the young stars.

Herschel's Whirlpool Galaxy.  Credit:  ESA and PACS team
Herschel's Whirlpool Galaxy. Credit: ESA and PACS team

Source: OSHI

WISE Launches to Begin All-Sky Survey (Video)

WISE launch. Image Credit: Bill Hartenstein/United Launch Alliance

NASA’s Wide-field Infrared Survey Explorer, or WISE, successfully lifted off this morning on its way to map the entire sky in infrared light. A Delta II rocket carrying the spacecraft launched at 6:09 a.m. PST (9:09 a.m. EST) from Vandenberg Air Force Base in California. WISE quickly began transmitting data – just 10 seconds after spacecraft separation — and all through the events that lead to bringing the satellite into a polar orbit 326 miles above Earth.

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“WISE thundered overhead, lighting up the pre-dawn skies,” said William Irace, the mission’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “All systems are looking good, and we are on our way to seeing the entire infrared sky better than ever before.”

Because the instrument sees the infrared, or heat, signatures of objects, it must be kept at chilly temperatures. Its coldest detectors are less than minus 447 degrees Fahrenheit.

“WISE needs to be colder than the objects it’s observing,” said Ned Wright of UCLA, the mission’s principal investigator. “Now we’re ready to see the infrared glow from hundreds of thousands of asteroids, and hundreds of millions of stars and galaxies.”

With the spacecraft stable, cold and communicating with mission controllers at JPL, a month-long checkout and calibration is underway.

WISE will see the infrared colors of the whole sky with sensitivity and resolution far better than the last infrared sky survey, performed 26 years ago. The space telescope will spend nine months scanning the sky once, then one-half the sky a second time. The primary mission will end when WISE’s frozen hydrogen runs out, about 10 months after launch.

WISE will catalog a variety of astronomical targets. Near-Earth asteroids, stars, planet-forming disks and distant galaxies all will be easy for the mission to see. Hundreds of millions of objects will populate the WISE atlas, providing astronomers and other space missions, such as NASA’s planned James Webb Space Telescope, with a long-lasting infrared roadmap.

Source: NASA

NASA to Launch WISE on Friday

An artist's rendering of the WISE satellite, which will survey the sky in the infrared. Image Credit: NASA/JPL

NASA is getting WISE to the Universe this Friday. That is, they’re launching the Wide-field Infrared Survey Explorer, a new infrared space telescope that will survey objects in our Solar System and beyond, looking for asteroids and brown dwarfs close to home, and protoplanetary disks and newborn stars far off.

The WISE mission is another in a series of all-sky surveys that have become so very effective for research. The satellite will spend six months mapping the entire sky in the infrared, after which it will make a second, three-month pass to further refine the mapping. Rather than looking at any specific objects, the satellite will survey everything it can see with its infrared eyes, providing a detailed catalog of infrared-emitting objects for followup with telescopes like the Spitzer Space Telescope, the Herschel Space Observatory and the upcoming James Webb Space Telescope.

Infrared instruments detect heat, so the instrument must be cooled to a chilly 17 Kelvin (-265 degrees Celsius/ -445 degrees Fahrenheit). Otherwise, it would detect its own heat signature. This is accomplished by packing it in a cryostat, which is basically a large thermos filled with solid hydrogen. The cryostat is expected to keep the instrument cool enough for about 10 months of observation after the launch.

WISE is all ready to go, with the chilled instrument stowed safely in the nosecone that will fit atop a Delta II rocket. WISE will launch from Vandenberg Air Force Base in California on Friday, Dec. 11, between 9:09 a.m. and 9:23 a.m. EST. NASA will have live coverage of the launch available on NASA TV.

WISE tucked safely in its nose cone, ready for launch aboard a Delta II rocket this Friday. Image Credit:United Launch Alliance/ JPL-Caltech

Objects that the WISE telescope will pick up include asteroids in our own Solar System that remain undetected because they are invisible in visible light. By doing an all-sky survey, WISE is expected to see hundreds of thousands of asteroids in our Solar System that haven’t been discovered, hundreds of them lying in the path of the Earth’s orbit. By cataloging these Earth orbit-crossing objects, astronomers can get a better idea of what threats from asteroid impact are lurking in the dark.

WISE will also be sensitive enough to pick up brown dwarfs, objects that straddle the line between planet and star. Though they are massive, they don’t quite make the cut for igniting nuclear fusion in their cores, but are warm enough to emit infrared light. It’s thought that there are quite a few of these objects in our own back yard waiting to be discovered, and WISE may double or triple the amount of star-like objects that are within 25 light-years of the Earth.

In addition to these smaller, closer finds, WISE will be able to see ultra-luminous infrared galaxies out in the distant regions of the Universe. These galaxies are bright in the infrared, but are invisible to telescopes that can only see in the visible light spectrum. The catalog may be a boon to extrasolar planet hunters, as the protoplanetary disks from which these planets form will be another object visible to the instrument.

The WISE telescope will have polar orbit with an altitude of 525 km (326 miles), and will circle the Earth 15 times each day. Snapshots of the sky will be taken every eleven seconds, allowing the instrument to image each position on the sky in the telescope’s field of view a minimum of eight times.

Be sure to check back with us for further coverage of the WISE launch on Friday!

Source: NASA press release, WISE mission site

Get the Big Picture of the Milky Way at the Adler Planetarium

Spitzer infrared image on display at the Adler Planetarium. Credit: Adler

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Astronomy is all about getting the big picture of our place in the cosmos, but some pictures are bigger than others. This one is really big. The world’s largest image of our Milky Way galaxy went on display today at the Adler Planetarium in Chicago. The image spans an area of 37 meters (120 feet) long by 1 meter (3 feet) wide at its sides, bulging to 2 meters (6 feet) to show the center of our humongous galaxy. The panorama represents 800,000 separate images taken by the Spitzer Space Telescope over a five-year period.


“This is the highest-resolution, largest, most sensitive infrared picture ever taken of our Milky Way,” said Sean Carey of NASA’s Spitzer Science Center, speaking when the image was unveiled in 2008 at the American Astronomical Society meeting in St. Louis (see our article and image of the unveiling). “Where previous surveys saw a single source of light, we now see a cluster of stars. With this data, we can learn how massive stars form, map galactic spiral arms and make a better estimate of our galaxy’s star-formation rate.”

Spitzer Survey image compiled.  Credit: NASA/JPL
Spitzer Survey image compiled. Credit: NASA/JPL

Data from Spitzer’s Infrared Array Camera (IRAC) and the Multiband Imaging Photometer were used to create the image.

If you want to download a very large version of this image (2400 x 3000) click here — warning: very big file.

From our vantage point on Earth, we see the Milky Way as a blurry, narrow band of light that stretches across the sky. In the visible, we only see about 5% of what’s actually out there. But with Spitzer’s dust-piercing infrared eyes, astronomers have peered 60,000 light-years away into this fuzzy band, called the galactic plane, and saw all the way to the other side of the galaxy.

The panorama reveals star formation as never seen before on both the large and small scale. Most of the star forming regions had not been seen before this project was undertaken.

I had the good fortune of seeing the image in St. Louis, and I highly recommend taking the opportunity to go see it at the Adler Planetarium if you are in Chicago. Here’s a video that explains how astronomers took the images and put them all together to form this gigantic panorama.

*Serendipitously, I am currently at the dotAstronomy conference where Eli Bressert from the Chandra X-Ray Center talked about the GLIMPSE Viewer. Here’s the link to see the Spitzer image with GLIMPSE (Galactic Legacy Infrared Midplane Extraordinaire).

Adler Planetarium is located at 1300 South Lake Shore Drive, Chicago, Ill., 60605. Phone: 312-922-7827. Adler Planetarium website. .

Infrared Spectroscopy

Silicates in Alien Asteroids. Credit: NASA/JPL/Caltech

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Infrared spectroscopy is spectroscopy in the infrared (IR) region of the electromagnetic spectrum. It is a vital part of infrared astronomy, just as it is in visual, or optical, astronomy (and has been since lines were discovered in the spectrum of the Sun, in 1802, though it was a couple of decades before Fraunhofer began to study them systematically).

For the most part, the techniques used in IR spectroscopy, in astronomy, are the same or very similar to those used in the visual waveband; confusingly, then, IR spectroscopy is part of both infrared astronomy and optical astronomy! These techniques involve use of mirrors, lenses, dispersive media such as prisms or gratings, and ‘quantum’ detectors (silicon-based CCDs in the visual waveband, HgCdTe – or InSb or PbSe – arrays in IR); at the long-wavelength end – where the IR overlaps with the submillimeter or terahertz region – there are somewhat different techniques.

As infrared astronomy has a much longer ground-based history than a space-based one, the terms used relate to the windows in the Earth’s atmosphere where lower absorption spectroscopy makes astronomy feasible … so there is the near-IR (NIR), from the end of the visual (~0.7 &#181m) to ~3 &#181m, the mid (to ~30 &#181m), and the far-IR (FIR, to 0.2 mm).

As with spectroscopy in the visual and UV wavebands, IR spectroscopy in astronomy involves detection of both absorption (mostly) and emission (rather less common) lines due to atomic transitions (the hydrogen Paschen, Brackett, Pfund, and Humphreys series are all in the IR, mostly NIR). However, lines and bands due to molecules are found in the spectra of nearly all objects, across the entire IR … and the reason why space-based observatories are needed to study water and carbon dioxide (to take just two examples) in astronomical objects. One of the most important class of molecules (of interest to astronomers) is PAHs – polycyclic aromatic hydrocarbons – whose transitions are most prominent in the mid-IR (see the Spitzer webpage Understanding Polycyclic Aromatic Hydrocarbons for more details).

Looking for more info on how astronomers do IR spectroscopy? Caltech has a brief introduction to IR spectroscopy. The ESO’s Very Large Telescope (VLT) has several dedicated instruments, including VISIR (which is both an imager and spectrometer, working in the mid-IR); CIRPASS, a NIR integrated field unit spectrograph on Gemini; Spitzer’s IRS (a mid-IR spectrograph); and LWS on the ESA’s Infrared Space Observatory (a FIR spectrometer).

Universe Today stories related to IR spectroscopy include Infrared Sensor Could Be Useful on Earth Too, Search for Origins Programs Shortlisted, and Jovian Moon Was Probably Captured.

Infrared spectroscopy is covered in the Astronomy Cast episode Infrared Astronomy.

Sources:
http://en.wikipedia.org/wiki/Infrared_spectroscopy
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/InfraRed/infrared.htm
http://www.chem.ucla.edu/~webspectra/irintro.html

Herschel Telescope Makes First Test Observations

Herschel's view of M51. Credit: ESA & the PACS Consortium

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The Herschel Telescope has given us a sneak preview of the infrared observational goodness we can expect from this new space telescope. The protective cryocover was taken off on June 14, and Herschel opened its ‘eyes,’ using the Photoconductor Array Camera and Spectrometer to take a few images of M51, ‘the whirlpool galaxy’ for a first test observation. The telescope obtained images in three colors from the observation, showing this largest of infrared space telescopes ever flown is functioning in fine form. Wonderful!

The above image shows the famous ‘whirlpool galaxy’, first observed by Charles Messier in 1773, who provided the designation Messier 51 (M51). This spiral galaxy lies relatively nearby, about 35 million light-years away, in the constellation Canes Venatici. M51 was the first galaxy discovered to harbor a spiral structure.

The image is a composite of three observations taken at 70, 100 and 160 microns, taken by Herschel’s Photoconductor Array Camera and Spectrometer (PACS) on June 14 and 15.

M51 seen by Spitzer (left) and Herschel (right). Credit: ESA
M51 seen by Spitzer (left) and Herschel (right). Credit: ESA

As a comparision, to the left is the best image of M51, taken by NASA’s Spitzer Space Telescope, with the Multiband Imaging Photometer for Spitzer (MIPS), and on the right is Herschel’s observation at 160 microns. The obvious advantage of the larger size of the telescope is clearly reflected in the much higher resolution of the image: Herschel reveals structures that cannot be discerned in the Spitzer image.

And here is Herschel’s glimpse of M51 at 70, 100, 160 microns:

M51 Herschel image at 160, 100 and 70 microns: Credit:  ESA
M51 Herschel image at 160, 100 and 70 microns: Credit: ESA

So, the shorter the wavelength, the sharper the image, showing the quality of Herschel’s optics.

Thanks, Herschel for a wonderful sneak preview of great images to come!

Source: ESA