A visible light image from ESO of the reflection nebula Messier 78. Credit: ESO and Igor Chekalin
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Here’s another “Hidden Treasure” from the European Southern Observatory, from the astrophotography competition where amateurs create images from unused ESO data. In this new image of Messier 78, brilliant starlight ricochets off dust particles in the nebula, illuminating it with scattered blue light and creating what is called a reflection nebula. Almost like fog around a street light, a reflection nebula shines only with the light from an embedded source that illuminates the dust. This image was taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. Comparing this image with others previously taken of Messier 78 shows that remarkably, this object has changed significantly in the last ten years.
Messier 78 can easily be observed with a small telescope, being one of the brightest reflection nebulae in the sky. It lies about 1350 light-years away in the constellation of Orion (The Hunter) and can be found northeast of the easternmost star of Orion’s belt.
For those of you who want to take a look on your own:
Right Ascension: 05:46.7
Declination: +00:03
Distance: 1.6 (kly)
Visual Brightness: Magnitude 8.3
This image contains many other striking features apart from the glowing nebula. A thick band of obscuring dust stretches across the image from the upper left to the lower right, blocking the light from background stars. In the bottom right corner, many curious pink structures are also visible, which are created by jets of material being ejected from stars that have recently formed and are still buried deep in dust clouds.
Two bright stars, HD 38563A and HD 38563B, are the main powerhouses behind Messier 78. However, the nebula is home to many more stars, including a collection of about 45 low mass, young stars (less than 10 million years old) in which the cores are still too cool for hydrogen fusion to start, known as T Tauri stars. Studying T Tauri stars is important for understanding the early stages of star formation and how planetary systems are created.
Messier 78 region taken in 2006 (below) with the 4-metre Mayall telescope at Kitt Peak, Arizona with a new image from ESO.Credit: ESO/T. A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOAO/AURA/NSF and Igor Chekalin
But this object has changed significantly in the last ten years. In February 2004 the experienced amateur observer Jay McNeil took an image of this region with a 75 mm telescope and was surprised to see a bright nebula — the prominent fan shaped feature near the bottom of this picture — where nothing was seen on most earlier images. This object is now known as McNeil’s Nebula and it appears to be a highly variable reflection nebula around a young star.
This color picture was created from many monochrome exposures taken through blue, yellow/green and red filters, supplemented by exposures through an H-alpha filter that shows light from glowing hydrogen gas. The total exposure times were 9, 9, 17.5 and 15.5 minutes per filter, respectively.
The HARPS-N spectrograph will be installed on the 3.6-meter Telescopio Nazionale Galileo in the Canary Islands. Credit: INAF
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With the Kepler spacecraft finding over 1,200 planetary candidates, the next step is verifying their actual status. That will be a big job, but help is on the way. In April 2012, a new spectrograph called HARPS-North will come online to help confirm and characterize Kepler’s planetary candidates. It will be mounted on the 3.6-meter Telescopio Nazionale Galileo (TNG) in the Canary Islands.
“The Kepler mission gives us the size of a planet, based on the amount of light it blocks when it passes in front of its star. Now we need to measure planetary masses, so that we can calculate the densities. That will allow us to distinguish rocky planets and water worlds from ones dominated by atmospheres of hydrogen and helium,” explained astronomer David Latham from the Harvard-Smithsonian Center for Astrophysics (CfA).
If the name HARPS (High-Accuracy Radial velocity Planet Searcher) is familiar, it is because this new instrument is a duplicate the successful design of an existing instrument in the Southern Hemisphere, the original HARPS spectrograph whichoperates on the 3.6-meter European Southern Observatory telescope at La Silla, Chile. At the TNG telescope, the new HARPS-North will be able to study the same region of the sky viewed by the Kepler spacecraft, within the northern constellations of Cygnus and Lyra.
The Harvard-Smithsonian CfA is part of an international collaboration building the new instrument.
Kepler main field of view. Credit: NASA/JPL - Caltech
Verifying a exoplanet can be tricky. In some circumstances, an eclipsing binary star can mimic the shallow dimming due to a planet crossing in front of its star. Ground-based measurements are needed to verify an orbiting world by spotting the gravitational wobbles it induces in its host star, in a method known as radial velocity.
A spectrograph operates by splitting the light from a star into its component wavelengths or colors, much like a prism. Chemical elements absorb light of specific colors, leaving dark lines in the star’s spectrum. Those lines shift position slightly due to the Doppler shift created by the gravitational tug of an orbiting planet on its star.
The new HARPS-North will be augmented by technology now under development, such as a laser comb for wavelength calibration, which will allow it to detect subtle radial-velocity signals.
“We have set up an enthusiastic collaboration among various institutions to build a northern copy of HARPS. We all expect HARPS-N to be as successful as its southern ‘brother,'” said HARPS-N principal investigator Francesco Pepe of the Astronomical Observatory of Geneva.
“HARPS-N will pursue the most interesting targets found by Kepler, at a level that no one else in the world can do,” said Dimitar Sasselov, Director of the Harvard Origins of Life Initiative. “HARPS-N will partner with Kepler to characterize worlds enough like Earth that they might be able to support life as we know it.”
In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second — an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU).
The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. “Every day, I told myself, ‘I have to find a pulsar. I better find a pulsar before this class ends,'” said Mabry.
When she actually made the discovery, she could barely contain her excitement. “I started screaming and jumping up and down.”
Thompson was similarly expressive. “After three years of searching, I hadn’t found a single thing,” he said, “but when I did, I threw my hands up in the air and said, ‘Yes!’.”
Snider said, “It actually feels really neat to be the first person to ever see something like that. It’s an uplifting feeling.”
As part of the PSC, the students analyze real data from NRAO’s Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students’ teachers — Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School — all introduced the PSC in their classes, and interested students formed teams to continue the work.
Even before the discovery, Mabry simply enjoyed the search. “It just feels like you’re actually doing something,” she said. “It’s a good feeling.”
Basics of a Pulsar CREDIT: Bill Saxton, NRAO/AUI/NSF
Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the follow-up observations, and Thompson joined online.
“Observing with the students is very exciting. It gives the students a chance to learn about radio telescopes and pulsar observing in a very hands-on way, and it is extra fun when we find a pulsar,” said Rosen.
Snider, on the other hand, said, “I got very, very nervous. I expected when I went there that I would just be watching other people do things, and then I actually go to sit down at the controls. I definitely didn’t want to mess something up.”
Everything went well, and the observations confirmed that the students had found an exotic pulsar. “I learned more in the two hours in the control room than I would have in school the whole day,” Mabry said.
Pulsars are spinning neutron stars that sling lighthouse beams of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its normal life. With no nuclear fuel left to produce energy to offset the stellar remnant’s weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name neutron star. One tablespoon of material from a pulsar would weigh 10 million tons — as much as a supertanker.
The object that the students discovered is in a special class of pulsar that spins very fast – in this case, about 30 times per second, comparable to the speed of a kitchen blender.
“The big question we need to answer first is whether this is a young pulsar or a recycled pulsar,” said Maura McLaughlin, an astronomer at WVU. “A pulsar spinning that fast is very interesting as it could be newly born or it could be a very old, recycled pulsar.”
A recycled pulsar is one that was once in a binary system. Material from the companion star is deposited onto the pulsar, causing it to speed up, or be recycled. Mystery remains, however, about whether this pulsar has ever had a companion star.
If it did, “it may be that this pulsar had a massive companion that exploded in a supernova, disrupting its orbit,” McLaughlin said. Astronomers and students will work together in the coming months to find answers to these questions.
The PSC is a joint project of the National Radio Astronomy Observatory and West Virginia University, funded by a grant from the National Science Foundation. 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 the GBT, a giant, 17-million-pound telescope.
Some 300 hours of observing data were reserved for analysis by student teams. Thompson, Snider, and Mabry have been working with about 170 other students across the country. The responsibility for the work, and for the discoveries, is theirs. They are trained by astronomers and by their teachers to distinguish between pulsars and noise. The students’ collective judgment sifts the pulsars from the noise.
All three students had analyzed thousands of data plots before coming upon this one. Casey Thompson, who has been with the PSC for three years, has analyzed more than 30,000 plots.
“Sometimes I just stop and think about the fact that I’m looking at data from space,” Thompson said. “It’s really special to me.”
In addition to this discovery, two other astronomical objects have been discovered by students. In 2009, Shay Bloxton of Summersville, WV, discovered a pulsar that spins once every four seconds, and Lucas Bolyard of Clarksburg, WV, discovered a rapidly rotating radio transient, which astronomers believe is a pulsar that emits radio waves in bursts.
Those involved in the PSC hope that being a part of astronomy will give students an appreciation for science. Maybe the project will even produce some of the next generation of astronomers. Snider, surely, has been inspired.
“The PSC changed my career path,” confessed Thompson. “I’m going to study astrophysics.”
Snider is pleased with the idea of contributing to scientific knowledge. “I hope that astronomers at Green Bank and around the world can learn something from the discovery,” he said.
Mabry is simply awed. “We’ve actually been able to experience something,” she said.
The PSC will continue through 2011. Teachers interested in participating in the program can learn more at this link.
During its one-year mission, NASA's Wide-field Infrared Survey Explorer, or WISE, mapped the entire sky in infrared light. Among the multitudes of astronomical bodies that have been discovered by the NEOWISE portion of the WISE mission are 20 comets. Image credit: NASA/JPL-Caltech/UCLA
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The WISE spacecraft has completed a special mission called NEOWISE, looking for small bodies in the solar system, and has discovered a plethora of previously unknown objects. The NEOWISE mission found 20 comets, more than 33,000 asteroids in the main belt between Mars and Jupiter, and 134 near-Earth objects (NEOs). More data from NEOWISE also have the potential to reveal a brown dwarf even closer to us than our closest known star, Proxima Centauri, if such an object does exist. Likewise, if there is a hidden gas-giant planet in the outer reaches of our solar system, data from WISE and NEOWISE could detect it.
“WISE has unearthed a mother lode of amazing sources, and we’re having a great time figuring out their nature,” said Edward (Ned) Wright, the principal investigator of WISE at UCLA.
“Even just one year of observations from the NEOWISE project has significantly increased our catalog of data on NEOs and the other small bodies of the solar systems,” said Lindley Johnson, NASA’s program executive for the NEO Observation Program.
The NEOs are asteroids and comets with orbits that come within 45 million kilometers (28 million miles) of Earth’s path around the sun.
The NEOWISE mission made use of the the WISE spacecraft, the Wide-field Infrared Survey Explorer that launched in December 2009. WISE scanned the entire celestial sky in infrared light about 1.5 times. It captured more than 2.7 million images of objects in space, ranging from faraway galaxies to asteroids and comets close to Earth.
However, in early October 2010, after completing its prime science mission, the spacecraft ran out of the frozen coolant that keeps its instrumentation cold. But two of its four infrared cameras remained operational, which were still optimal for asteroid hunting, so NASA extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more asteroids and comets, and to finish one complete scan of the main asteroid belt.
Now that NEOWISE has successfully completed a full sweep of the main asteroid belt, the WISE spacecraft will go into hibernation mode and remain in polar orbit around Earth, where it could be called back into service in the future.
In addition to discovering new asteroids and comets, NEOWISE also confirmed the presence of objects in the main belt that had already been detected. In just one year, it observed about 153,000 rocky bodies out of approximately 500,000 known objects. Those include the 33,000 that NEOWISE discovered.
NEOWISE also observed known objects closer and farther to us than the main belt, including roughly 2,000 asteroids that orbit along with Jupiter, hundreds of NEOs and more than 100 comets.
These observations will be key to determining the objects’ sizes and compositions. Visible-light data alone reveal how much sunlight reflects off an asteroid, whereas infrared data is much more directly related to the object’s size. By combining visible and infrared measurements, astronomers also can learn about the compositions of the rocky bodies — for example, whether they are solid or crumbly. The findings will lead to a much-improved picture of the various asteroid populations.
NEOWISE took longer to survey the whole asteroid belt than WISE took to scan the entire sky because most of the asteroids are moving in the same direction around the sun as the spacecraft moves while it orbits Earth. The spacecraft field of view had to catch up to, and lap, the movement of the asteroids in order to see them all.
“You can think of Earth and the asteroids as racehorses moving along in a track,” said Amy Mainzer, the principal investigator of NEOWISE at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We’re moving along together around the sun, but the main belt asteroids are like horses on the outer part of the track. They take longer to orbit than us, so we eventually lap them.”
NEOWISE data on the asteroid and comet orbits are catalogued at the NASA-funded International Astronomical Union’s Minor Planet Center, a clearinghouse for information about all solar system bodies at the Smithsonian Astrophysical Observatory in Cambridge, Mass. The science team is analyzing the infrared observations now and will publish new findings in the coming months.
The first batch of observations from the WISE mission will be available to the public and astronomical community in April.
A patch of the sky 15 degrees wide (as large as a thousand full moons) taken in a single shot by LOFAR. The image reveals the stunning variety of objects which surround the quasar 3C196. Credit: ASTRON and LOFAR
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An array of radio telescopes has connected for the first time to its various locations across Europe, creating the largest telescope in the world at almost 1000 km wide. With the connection, the LOFAR telescope has delivered its first ‘radio pictures’. The images of the 3C196 quasar, a black hole in a distant galaxy, were taken in January 2011 by the International LOFAR Telescope (ILT). LOFAR is a network of radio telescopes designed to study the sky at the lowest radio frequencies accessible from the surface of the Earth with unprecedented resolution.
The UK based telescope at Chilbolton Observatory in Hampshire, was added to the network, and is the western most ‘telescope station’ in LOFAR.
“This is a very significant event for the LOFAR project and a great demonstration of what the UK is contributing”, said Derek McKay-Bukowski, STFC/SEPnet Project Manager at LOFAR Chilbolton. “The new images are three times sharper than has been previously possible with LOFAR. LOFAR works like a giant zoom lens – the more radio telescopes we add, and the further apart they are, the better the resolution and sensitivity. This means we can see smaller and fainter objects in the sky which will help us to answer exciting questions about cosmology and astrophysics.”
A close up of the quasar 3C196 (Credit: ASTRON and LOFAR)
“This is fantastic”, said Professor Rob Fender, LOFAR-UK Leader from the University of Southampton. “Combining the LOFAR signals together is a very important milestone for this truly international facility. For the first time, the signals from LOFAR radio telescopes in the Netherlands, France, Germany and the United Kingdom have been successfully combined in the LOFAR BlueGene/P supercomputer in the Netherlands. The connection between the Chilbolton telescope and the supercomputer requires an internet speed of 10 gigabits per second – over 1000 times faster than the typical home broadband speeds,” said Professor Fender. “Getting that connection working without a hitch was a great feat requiring close collaboration between STFC, industry, universities around the country, and our international partners.”
“The images show a patch of the sky 15 degrees wide (as large as a thousand full moons) centred on the quasar 3C196”, said Dr Philip Best, Deputy LOFAR-UK leader from the University of Edinburgh. “In visible light, quasar 3C196 (even through the Hubble Space Telescope) is a single point. By adding the international stations like the one at Chilbolton we reveal two main bright spots. This shows how the International LOFAR Telescope will help us learn about distant objects in much more detail.”
LOFAR was designed and built by ASTRON in the Netherlands and is currently being extended across Europe. As well as deep cosmology, LOFAR will be used to monitor the Sun’s activity, study planets, and understand more about lightning and geomagnetic storms. LOFAR will also contribute to UK and European preparations for the planned global next generation radio telescope, the Square Kilometre Array (SKA).
3D images of HD 62623, obtained with the VLTI (left), compared to the model of a rotating disk (right). In the boxes, the gas kinematics is shown (3rd dimension): blue-coloured gas approaches the observer, while red-coloured gas recedes from the observer. The size of the inner gas disk of approx. 2 milli-arcseconds corresponds to 1.3 astronomical units (distance Earth-Sun), while the outer dust ring seen in the images has a radius corresponding to 4 astronomical units, assuming 2100 light years as distance to HD 62623. Images: F. Millour et al.
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For several years, astronomers have been trying to get a good look at a peculiar supergiant star that is surrounded by a disk of gas and dust. The star, HD 62623, is one of the very few known supergiant stars to have such a disk. These disks are generally only associated with smaller, young stars, as supergiants have strong stellar winds that would blow away any surrounding plasma and debris. Now, using long-baseline stellar interferometry with the “Amber” instrument at ESO’s Very Large Telescope interferometer, a team of astronomers were able to capture, for the first time, a 3-D view of this strange star and its surrounding environment, which revealed a hidden secret: a companion star is likely responsible for the surrounding disk.
“Thanks to our interferometric observations with Amber we could synthetize a 3-D image of HD 62623 as seen through a virtual 130 m-diameter telescope”, says Florentin Millour, leading author of the study, from Observatoire de la Côte d’Azur. “The resolution is an order of magnitude higher compared with the world’s largest optical telescopes of 8-10 m diameter.”
HD 62623 is an exotic, hot, supergiant star. Supergiants are the most massive stars out there, ranging between 10 to 70 solar masses, and can range in brightness from 30,000 to hundreds of thousands of times the output of our Sun. They have very short lifespans, living from 30 million down to just a few hundred thousand years. Supergiants seem to always detonate as Type II supernovae at the end of their lives.
“Our new 3D image locates the dust-forming region around HD 62623 very precisely, and it provides evidence for the rotation of the gas around the central star,” said co-author Anthony Meilland from Max Planck Institute for Radio Astronomy. “This rotation is found to be Keplerian, the same way the Solar system planets rotate around the Sun.”
The companion star, although not seen directly because its light couldn’t be resolved among the brightness of HD62623, was detected by a central cavity between the gas disk and HD 62623. The companion is thought to be approximately the mass of our Sun, and its presence would explain the exotic characteristics of HD 62623, which has many similar characteristics to a monster among the old stars within our Galaxy, Eta Carinae.
HD 62623 is located in the constellation Cygnus near another bright supergiant, Deneb of the summer triangle. Deneb however, like most other supergiants, has no surrounding disk.
Four domes of the 1.8 m Auxiliary Telescopes (AT), utilized for the Very Large Telescope Interferometer (VLTI). ESO, Cerro Paranal, Chile. Image: F. Millour, OCA, Nice, France.
The images obtained with the Amber instrument combines spatial and velocity information, showing not only the shape of the close environment of HD 62623, but also its kinematics or motion. Up to now, the necessary kinematics information was missing in such images.
The astronomers were able to “disentangle” the dust and gas emission in the HD 62623 circumstellar disc, and measure the dusty disc inner rim. They also constrained the inclination angle and the position angle of the major-axis of the disc.
The new 3D imaging technique used by the team is equivalent to integral-field spectroscopy, but gives access to a 15 times larger angular resolution or capacity to detect fine details in the images. “With these new capacities, the VLTI will be able to provide a better comprehension of many sky targets, too small to be resolved by the largest telescopes,” said Millour. “We could aim at young stellar disks or jets, or even the central regions of active galaxies.”
‘First Light’ for VIRUS-W: This image (from the Sloan Digital Sky Survey) shows the galaxy NGC2903 and the field of view of the spectrograph. Credit: SDSS
The new observing instrument VIRUS-W, built by the Max Planck Institute for Extraterrestrial Physics and the University Observatory Munich, saw “first light” on 10th November at the Harlan J. Smith Telescope of the McDonald observatory in Texas. Its first images of a spiral galaxy about 30 million light-years away are an impressive confirmation of the capabilities of the instrument, which can determine the motion of stars in near-by galaxies to a precision of a few kilometers per second.
As an imaging field spectrograph, VIRUS-W can simultaneously produce 267 individual spectra – one for each of its glass fibers. By dispersing the light into its constituent colors, astronomers thus are able to study properties such as the velocity distribution of the stars in a galaxy. For this they use the so called Doppler shift, which means that the light from stars moving towards or away from us is shifted to blue or red wavelengths, respectively. This effect can also be observed on Earth, when a fast vehicle, such as a racing car, is driving past: the sound of the approaching car is higher, while for the departing car it is lower.
VIRUS-W´s unique feature is the combination of a large field of view (about 1×2 arcminutes) with a relatively high spectral resolution. With the large field of view astronomers can study near-by galaxies in just one or few pointings, while the high spectral resolution permits a very accurate determination of the velocity dispersion in these objects. In this way the astronomers obtain the large-scale kinematic structure of near-by spiral galaxies, which gives important insight into their formation history.
These are the first observational data taken by VIRUS-W at the beginning of November. The false colour image in the bottom row, left, shows an enlarged area of the galaxy NGC2903 shown above. Credit: M. Fabricius, MPE
Most galaxies are too distant and the separation between the billions upon billions of stars is too small to resolve it with even the best, cutting-edge instruments. The astronomers therefore cannot study individual stars but only the average motion along a specific line of sight.
The measured velocity distributions are characterized by two parameters: The mean velocity reveals the large-scale motion of the stars along the line of sight. The velocity dispersion measures how much the velocities of the individual stars differ from this mean velocity. If the stars have more or less the same velocity, the dispersion is small, if they have very different velocities, the dispersion is broad. For spiral galaxies, where the stars travel in fairly regular circular orbits, the velocity dispersion is mostly small. In elliptical galaxies, however, the stars have rather disordered orbits and so the dispersion is broad.
With the high spectral resolution of VIRUS-W, the astronomers can investigate relatively small velocity dispersions, down to about 20 km/s. This was impressively confirmed by the first images taken by VIRUS-W of the near-by spiral galaxy NGC2903.
“When we attached VIRUS-W around midnight on the 10th of November to the 2.7m telescope, we were very happy to see that the data delivered by VIRUS-W was of science quality virtually from the first moment on,” says Maximilian Fabricius from the Max-Planck-Institute for Extraterrestrial Physics. “As the first galaxy to observe we had selected the strongly barred galaxy NGC2903 at a distance of about 30 million lightyears – right in front of our doorstep. The data we collected reveal a centrally increasing velocity dispersion from about 80 km/s to 120 km/s within the field of view of the instrument. This was a very exciting moment and only possible because of the remarkable teamwork during the commissioning with a lot of support by the observatory staff!” The observing time at the telescope was made available by the VENGA project, to which VIRUS-W will be contributing from the beginning of 2011 onwards. It will then provide detailed kinematic data to this study.
The main instrument for VENGA is VIRUS-P, a spectrograph operating at the 2,7m Harlan J. Smith-Teleskope of the McDonald observatory since 2007. This instrument is a prototype of the VIRUS spectrographs being developed for the HETDEX project led by the University of Texas in Austin. For a study of the large scale distribution of galaxies, HETDEX will combine about 100 spectrographs at the 9.2m Hobby-Eberly Telescope of the McDonald observatory to form one large instrument. VIRUS-W (where the W stands for a later mission at the Wendelstein telescope of the Munich Observatory) is based on the same basic VIRUS design. Because of its broader spectral coverage and despite its much lower resolution, the prototype VIRUS-P already gives interesting insight into the age and chemical composition of stars and the interstellar medium as well as information about the star formation rate.
This new image of the Orion Nebula was captured using the Wide Field Imager camera on the MPG/ESO 2.2-metre telescope at the La Silla Observatory, Chile. Credit: ESO and Igor Chekalin
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This dreamy look inside the Orion Nebula is the latest “Hidden Treasure” released by the European South Observatory, part of its contest for amateurs to sift through the mountain of data ESO has generated with their telescopes and create new images from old data. The data used for this image were selected by Igor Chekalin from Russia, and this was the seventh highest ranked entry in the competition; another of Igor’s images was the eventual overall winner.
The image is a composite of several exposures taken through a total of five different filters with the Wide Field Imager on the MPG/ESO 2.2-meter telescope at the La Silla Observatory, Chile.
The Orion Nebula, also known as Messier 42, is a huge complex of gas and dust where massive stars are forming and is the closest such region to the Earth. The glowing gas is so bright that it can be seen with the unaided eye and is a fascinating sight through a telescope. Despite its familiarity and closeness there is still much to learn about this stellar nursery. It was only in 2007, for instance, that the nebula was shown to be closer to us than previously thought: 1,350 light-years, rather than about 1,500 light-years.
The data was originally used to find that the faint red dwarfs in the star cluster associated with the glowing gas radiate much more light than had previously been thought. But the data had not been made into a color image, until now.
This illustration shows the wealth of information on scales both small and large available in the SDSS-III’s new image. The picture in the top left shows the SDSS-III view of a small part of the sky, centered on the galaxy Messier 33 (M33). The middle top picture is a further zoom-in on M33, showing the spiral arms of this galaxy, including the blue knots of intense star formation known as “HII regions.” The top right-hand picture is a further zoom into M33 showing the object NGC 604, which is one of the largest HII regions in that galaxy. The figure at the bottom is a map of the whole sky derived from the SDSS-III image, divided into the northern and southern hemispheres of our galaxy. Visible in the map are the clusters and walls of galaxies that are the largest structures in the entire universe.
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Today, the Sloan Digital Sky Survey-III (SDSS-III) is releasing the largest digital color image of the sky ever made, and it’s free to all. Just how big? Step inside and find out…
According to the American Astronomical Society press release, the image has been put together over the last decade from
millions of 2.8-megapixel images, thus creating a color image of more than a trillion pixels. Just how does that relate? Even a large format professional CCD camera will only produce about 11 million pixels and really big screen to view – but this terapixel image is so big and detailed that it would take 500,000 high-definition TVs to view it at its full resolution. Can you imagine?! “This image provides opportunities for many new scientific discoveries in the years to come,” exclaims Bob Nichol, a professor at the University of Portsmouth and Scientific Spokesperson for the SDSS-III collaboration.
Where did this huge astrophoto come from? The new image is at the heart of new data being released today by the SDSS-III collaboration at 217th American Astronomical Society meeting in Seattle. This new information, along with the previous data releases which it builds upon, gives astronomers the most comprehensive view of the night sky ever made. SDSS data have already been used to discover nearly half a billion astronomical objects, including asteroids, stars, galaxies and distant quasars. The latest, most precise positions, colors and shapes for all these objects are also being released today. (Time to update our software programs!) “This is one of the biggest bounties in the history of science,” says Professor Mike Blanton from New York University, who is leading the data archive work in SDSS-III. Blanton and many other scientists have been working for months preparing the release of all this data. “This data will be a legacy for the ages,” explains Blanton, “as previous ambitious sky surveys like the Palomar Sky Survey of the 1950s are still being used today.” And who among us hasn’t used the POSS program to confirm something we’ve seen or perhaps caught unexpectedly on an astrophotograph? “We expect the SDSS data to have that sort of shelf life,” comments Blanton.
So when did all of this begin? The image was started in 1998 using what was then the world’s largest digital camera: a 138-megapixel imaging detector on the back of a dedicated 2.5-meter telescope at the Apache Point Observatory in New Mexico, USA. Over the last decade, the Sloan Digital Sky Survey has scanned a third of the whole sky. Now, this imaging camera is being retired, and it will rightfully become a part of the permanent collection at the Smithsonian in recognition of its contributions to astronomy. “It’s been wonderful to see the science results that have come from this camera,” says Connie Rockosi, an astronomer from the University of California, Santa Cruz, who started working on the camera in the 1990s as an undergraduate student with Jim Gunn, Professor of Astronomy at Princeton University and SDSS-I/II Project Scientist. Rockosi’s entire career so far has paralleled the history of the SDSS camera. “It’s a bittersweet feeling to see this camera retired, because I’ve been working with it for nearly 20 years,” she says.
But what next? Thanks to such incredible resolution, the enormous image will form the cornerstone for new surveys of the Universe using the SDSS telescope. These surveys rely on other forms of data, such as spectra – an astronomical technique which employs specialized instruments to break the light from a star or galaxy into its component wavelengths. Spectra can be used to find the distances to distant galaxies, and the properties (such as temperature and chemical composition) of different
types of stars and galaxies. “We have upgraded the existing SDSS instruments, and we are using them to measure distances to over a million galaxies detected in this image,” explains David Schlegel, an astronomer from Lawrence Berkeley National Laboratory, and the Principal Investigator of the new SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Schlegel
explains that measuring distances to galaxies is more time-consuming than simply taking their pictures, but in return, it provides a detailed three-dimensional map of the galaxies’ distribution in space. This is the type of accuracy we could only dream of five decades ago.
According to the press release, BOSS started taking data in 2009 and will continue until 2014, explains Schlegel. Once finished, BOSS will be the largest 3-D map of galaxies ever made, extending the original SDSS galaxy survey to a much larger volume of the Universe. The goal of BOSS is to precisely measure how so-called “Dark Energy” has changed over the recent history of the universe. These measurements will help astronomers understand the nature of this mysterious substance. “Dark energy is the biggest conundrum facing science today,” says Schlegel, “and the SDSS continues to lead the way in trying to figure out what the heck it is!” In addition to BOSS, the SDSS-III collaboration has been studying the properties and motions of hundreds of thousands of stars in the outer parts of our Milky Way Galaxy. The survey, known as the Sloan Extension for Galactic Understanding and Exploration or SEGUE started several years ago but has now been completed as part of the first year of SDSS-III.
Need more? In conjunction with the image being released today, astronomers from SEGUE are also releasing the largest map of the outer galaxy ever released. “This map has been used to study the distribution of stars in our galaxy,” says Rockosi, the Principal Investigator of SEGUE. “We have found many streams of stars that originally belonged to other galaxies that were torn apart by the gravity of our Milky Way. We’ve long thought that galaxies evolve by merging with others; the SEGUE observations confirm this basic picture.”
So what’s next? SDSS-III is also undertaking two other surveys of our galaxy through 2014. The first, called MARVELS, will use a new instrument to repeatedly measure spectra for approximately 8,500 nearby stars like our own Sun, looking for the telltale wobbles caused by large Jupiter-like planets orbiting them. MARVELS is predicted to discover around a hundred new giant planets, as well as potentially finding a similar number of “brown dwarfs” that are intermediate between the most massive planets and the smallest stars. The second survey is the APO Galactic Evolution Experiment (APOGEE), which is using one of the largest infrared spectrographs ever built to undertake the first systematic study of stars in all parts of our galaxy; even stars on the other side of our galaxy beyond the central bulge. Such stars are traditionally difficult to study as their visible light is obscured by large amounts of dust in the disk of our galaxy. However, by working at longer, infrared wavelengths, APOGEE can study them in great detail, thus revealing their properties and motions to explore how the different components of our galaxy were put together. “The SDSS-III is an amazingly diverse project built on the legacy of the original SDSS and SDSS-II surveys,” summarizes Nichol. “This image is the culmination of decades of work by hundreds of people, and has already produced many incredible discoveries. Astronomy has a rich tradition of making all such data freely available to the public, and
we hope everyone will enjoy it as much as we have.”
I do believe we will…
(The SDSS-III Data Release Eight (DR8) can be found at http://www.sdss3.org/dr8. All data published as part of DR8 is freely available to other astronomers, scientists, and the public. Technical journal papers describing DR8 and the SDSS-III project are on the arXiv e-Print server (http://arxiv.org).)
Credits: American Astronomical Society Press Release, M. Blanton and the SDSS-III.
Scientists using NASA’s Fermi Gamma-ray Space Telescope have detected beams of antimatter produced above thunderstorms on Earth, a phenomenon never seen before.
Scientists think the antimatter particles were formed in a terrestrial gamma-ray flash (TGF), a brief burst produced inside thunderstorms and shown to be associated with lightning. It is estimated that about 500 TGFs occur daily worldwide, but most go undetected.
“These signals are the first direct evidence that thunderstorms make antimatter particle beams,” said Michael Briggs, a member of Fermi’s Gamma-ray Burst Monitor (GBM) team at the University of Alabama in Huntsville (UAH). He presented the findings Monday, during a news briefing at the American Astronomical Society meeting in Seattle. Continue reading “Fermi Telescope Catches Thunderstorms Hurling Antimatter into Space”
