DG 129 - In the Grip of the Scorpion's Claw

Gripped in the claw of the constellation Scorpius sits the reflection nebula DG 129, a cloud of gas and dust that reflects light from nearby, bright stars. This infrared view of the nebula was captured by NASA's Wide-field Infrared Survey Explorer, or WISE.

Viewed in visible light, this portion of the sky seems somewhat unremarkable. But in infrared light, a lovely reflection nebula is revealed. DG 129 was first cataloged by a pair of German astronomers, named Johann Dorschner and Josef Gärtler, in 1963.

Much like gazing at Earth-bound clouds, it is fun to use your imagination when looking at images of nebulae. Some people see this nebula as an arm and hand emerging from the cosmos. If you picture the "thumb" and "forefinger" making a circle, it is as though you are seeing a celestial "okay" sign.

The bright star on the right with the greenish haze is Pi Scorpii. This star marks one of the claws of the scorpion in the constellation Scorpius. It is actually a triple-star system located some 500 light-years away. Perhaps a cross-species celestial handshake is imminent?

The colors used in this image represent different wavelengths of infrared light. The image was constructed from frames taken after WISE ran out of some of the coolant needed to chill its infrared detectors and began to warm up. The WISE detector sensitive to 22-micron light has become too warm to produce good images, but the three shorter wavelength detectors continue to crank out over 7,000 pictures of the sky every day, like the ones that make up this picture. Blue represents infrared radiation at 3.4 microns, while green represents light with a wavelength of 4.6 microns. Red represents 12-micron infrared light.

Photo credit: NASA/JPL-Caltech/UCLA

Coreshine in the L183 Dark Cloud

This series of images from NASA's Spitzer Space Telescope shows a dark mass of gas and dust, called a core, where new stars and planets will likely spring up.

The image on the far right shows the core as seen at longer wavelengths of infrared light (8 microns); when viewed at this wavelength, the core appears dark. The middle image shows the core as seen at a shorter infrared wavelength (3.6 microns). In this view, the core lights up because it is deflecting starlight from nearby stars. This unexpected light, called coreshine, tells astronomers that the dust making up the core must be bigger than previously thought -- smaller particles would not have been big enough to scatter the light. The image on the left is a combination of the other two images.

This particular core lies deep within a larger dark cloud called L183. Spitzer's infrared vision allows it to peer into the dark cloud to see the even darker cores buried inside.

The observations were made with Spitzer's infrared array camera.

Photo credit:

LBN 114.55+00.22

Nebulae are enormous clouds of dust and gas occupying the space between the stars. Some have pretty names to match their good looks, for example the Rose Nebula, while others have much more utilitarian names. Such is the case with LBN 114.55+00.22, seen here in an image from NASA's Wide-field Infrared Survey Explorer, or WISE.

Named after the astronomer who published a catalog of nebulae in 1965, LBN stands for "Lynds Bright Nebula." The numbers 114.55+00.22 refer to nebula's coordinates in our Milky Way galaxy, serving as a sort of galactic home address.

Astronomers classify LBN 114.55+00.22 as an emission nebula. Unlike a reflection nebula, which reflects light from nearby stars, an emission nebula emits light. High-energy light blasted out from a nearby massive star strips away electrons from the nebula's hydrogen gas, causing the gas to become charged. These nebulae are also called HII regions, with the "H" standing for hydrogen and the "II" indicating that the gas is ionized. As the ionized gas begins to cool from a higher-energy state to a lower-energy state, it glows. In the case of LBN 114.55+00.22, dust blocks the view of most of this nebula in visible light. But the dust of the nebula is also warmed by the light of the young stars within, and WISE's infrared detectors see its beautiful infrared colors. Emission nebulae are usually found in the disks of spiral galaxies, and are places where new stars are forming.

In the lower left corner of the image is the bright red star IRAS 23304+6147, which is in the last phase of its life. As the hydrogen in its core burns out, the star will become a planetary nebula, ejecting material that absorbs visible light and glows in the infrared. This star's name comes from the 1983 survey mission Infrared Astronomical Satellite (IRAS).

Another bright object in this image is the supergiant variable star HIP 117078, seen above and to the right of the nebula. In this case, HIP stands for Hipparcos, a European Space Agency satellite that cataloged the positions of over 100,000 stars.

The colors used in this image represent specific wavelengths of infrared light. Blue and cyan represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars. Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust.

Photo credit: NASA/JPL-Caltech/UCLA

A Brief Discontinuity in the Space-Time Continuum

The Minister is sad to note that his home is going through some renovation work through early next week. Blogging is more or less halted until then, although, if he can find some time to do some posts, he'll try to put up some new material. In the meantime, please feel free to visit the archives of Areology, Ministry of Space Exploration, and Saturnology.

BP Psc: Stellar Cannibalism

The composite image on the left shows X-ray and optical data for BP Piscium (BP Psc), a more evolved version of our Sun about 1,000 light years from Earth. Chandra X-ray Observatory data are colored in purple, and optical data from the 3-meter Shane telescope at Lick Observatory are shown in orange, green and blue. BP Psc is surrounded by a dusty and gaseous disk and has a pair of jets several light years long blasting out of the system. A close-up view is shown by the artist's impression on the right. For clarity a narrow jet is shown, but the actual jet is probably much wider, extending across the inner regions of the disk. Because of the dusty disk, the star's surface is obscured in optical and near-infrared light. Therefore, the Chandra observation is the first detection of this star in any wavelength.

The disk and the jets, seen distinctly in the optical data, provide evidence for a recent and catastrophic interaction in which BP Psc consumed a nearby star or giant planet. This happened when BP Psc ran out of nuclear fuel and expanded into its "red giant" phase.

Jets and a disk are often characteristics of very young stars, so astronomers thought BP Psc might be one as well. However, the new Chandra results argue against this interpretation, because the X-ray source is fainter than expected for a young star. Another argument previously used against the possible youth of BP Psc was that it is not located near any star-forming cloud and there are no other known young stars in its immediate vicinity. The Chandra image supports this absence of a cluster of young stars, since multiwavelength studies show that most of the X-ray sources in the composite image are likely to be rapidly growing supermassive black holes in the centers of distant galaxies.

Credits: X-ray (NASA/CXC/RIT/J.Kastner et al), Optical (UCO/Lick/STScI/M.Perrin et al); Illustration: NASA/CXC/M.Weiss

Halfway to Endeavour Crater

NASA's Mars Exploration Rover Opportunity used its navigation camera to record this view at the end of a 111-meter (364-foot) drive on the 2,353rd Martian day, or sol, of the rover's mission on Mars (September 6, 2010). This sol's drive took Opportunity past the estimated halfway point of the approximately 19-kilometer (11.8-mile) journey from Victoria Crater to the much larger Endeavour Crater.

Opportunity began the trip from Victoria to Endeavour in September 2008 after two years of exploring in and around Victoria. After the rover science team selected Endeavour as the rover's next long-term destination, observations of Endeavour's rim by NASA's Mars Reconnaissance Orbiter revealed the presence of clay minerals. This finding makes the site an even more compelling science destination. Clay minerals, which form exclusively under wet conditions, have been found extensively on Mars from orbit, but have not been examined on the surface.

A portion of the Endeavour rim is visible on the horizon in this image. In the nearer ground, exposures of bright-toned outcrop are visible between crests of darker, wind-sculpted sand ripples.

Opportunity completed its three-month prime mission on Mars in April 2004 and has been operating as an extended mission since then.

Photo credit: NASA/JPL-Caltech

Messier 74 with Asteroid 3540 Protesilaos

It's a bird! It's a plane! Nope, it's an asteroid tracking its way across the sky with a beautiful spiral galaxy in the background. In the center of this new mosaic image captured by NASA's Wide-field Infrared Survey Explorer (WISE) is the galaxy Messier 74, with its spiral arms seen face-on. The bright reddish object moving across the lower right part of the image is the much closer asteroid 3540 Protesilaos, seen at different points in its orbit around the Sun. WISE observed and detected this previously known asteroid a total of ten times, although only a few of those frames were used in this mosaic.

Also known as NGC 628, the Messier 74 galaxy is between 24.5 and 36 million light-years away, and has a diameter of about 100,000 light-years. It is suspected to have a black hole at its center, with a mass equal to 10,000 suns. It is one of only a handful of known black holes with masses intermediate between the relatively smaller ones that form from collapsing stars and the supermassive black holes millions of times more massive than the sun, which are more typically found at the centers of galaxies. Although it is called a Messier object, Messier 74 was actually discovered by Pierre Mechain in 1780, who then told his friend Charles Messier about it. As one of the dimmest of all Messier objects, this galaxy is a challenge for amateur astronomers to see in visible light, but the WISE cameras captured it clearly in infrared light.

The colors used in this image represent different wavelengths of infrared radiation. Blue and cyan represent light at 3.4 and 4.6 microns, respectively. These colors show both nearby stars inside the Milky Way galaxy and the combined light of billions of stars that make up Messier 74. Green and red represent light from 12 and 22 microns, respectively. These colors show light from cooler objects and material. Dust in star-forming regions in Messier 74 traces its spiral structure. The coolest object in the picture is the asteroid 3540 Protesilaos.

This asteroid was first seen in 1973 by the German astronomer Freimut Börngen, who discovered more than 500 asteroids while he was researching galaxies. At the time that WISE observed 3540 Protesilaos, it was at a distance of 772 million kilometers from Earth (480 million miles, or about 43 light-minutes). It is classified as a Jupiter Trojan minor planet, which are small rocky bodies that share the same orbit around the Sun as the planet Jupiter. Based on the infrared observations, the WISE team estimates the asteroid to be about 90 kilometers (56 miles) across and to reflect only a few percent of the light that lands on it, which makes it about as dark as coal.

By convention, Trojan asteroids are named after the heroes from the Trojan War. In this case, asteroid 3540 is named after the hero Protesilaos. According to Greek mythology, Protesilaos was the first Greek to set foot on Trojan land during the war. Unfortunately for him, there was a prophecy that the first soldier in the war to step onto land from a battle ship would die. The prophecy quickly came true and Protesilaos was killed.

Photo credit: NASA/JPL-Caltech/UCLA

The Heart of a Rose

This composite image shows the Rosette star formation region, located about 5,000 light years from Earth. Data from the Chandra X-ray Observatory are colored red and outlined by a white line. The X-rays reveal hundreds of young stars clustered in the center of the image and additional fainter clusters on either side. Optical data from the Digitized Sky Survey and the Kitt Peak National Observatory (purple, orange, green and blue) show large areas of gas and dust, including giant pillars that remain behind after intense radiation from massive stars has eroded the more diffuse gas.

A recent Chandra study of the cluster on the right side of the image, named NGC 2237, provides the first probe of the low-mass stars in this satellite cluster. Previously only 36 young stars had been discovered in NGC 2237, but the Chandra work has increased this sample to about 160 stars. The presence of several X-ray emitting stars around the pillars and the detection of an outflow -- commonly associated with very young stars -- originating from a dark area of the optical image indicates that star formation is continuing in NGC 2237. By combining these results with earlier studies, the scientists conclude that the central cluster formed first, followed by expansion of the nebula, which triggered the formation of the neighboring clusters, including NGC 2237.

Photo credit: X-ray (NASA/CXC/SAO/J. Wang et al), Optical (DSS & NOAO/AURA/NSF/KPNO 0.9-m/T. Rector et al)

Comet 103/P Hartley 2

This first image of Comet 103P/Hartley 2 was taken from NASA's Deep Impact spacecraft 60 days prior to the spacecraft's flyby of the comet.

Seven successive one-minute exposures taken by the spacecraft's Medium Resolution Imager were combined to make this single image. The exposures were taken on September 5th beginning at about 6:30 a.m. PDT (9:30 a.m. EDT, 13:30 UTC). The comet was 60 million kilometers (37.2 million miles) from the spacecraft when the set of images were taken.

Photo credit: NASA/JPL-Caltech/University of Maryland

Update (27 October 2010): NASA has released three videos with respect to the upcoming rendezvous with Comet Hartley 2:
PIA13546: EPOXI's Trip to Meet Comet Hartley 2 - A video showing the orbital trajectories of the Earth, Comet Hartley 2 and the Deep Impact spacecraft.
PIA13547: Hartley 2 on the Move - A time lapse animation of the comet by Deep Impact as the spacecraft gets nearer (from 21 million kilometers on October 15th to just under 12 million kilometers on October 24th).
PIA13548: Comet Hartley 2 Gets a Visitor - An artist's animation showing the flyby of Deep Impact past the comet from the spacecraft's perspective.

NGC 300

ESO has released a spectacular new image of NGC 300, a spiral galaxy similar to the Milky Way, and located in the nearby Sculptor Group of galaxies. Taken with the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile, this 50-hour exposure reveals the structure of the galaxy in exquisite detail. NGC 300 lies about six million light-years away and appears to be about two thirds the size of the full Moon on the sky.

Originally discovered from Australia by the Scottish astronomer James Dunlop early in the nineteenth century, NGC 300 is one of the closest and most prominent spiral galaxies in the southern skies and is bright enough to be seen easily in binoculars. It lies in the inconspicuous constellation of Sculptor, which has few bright stars, but is home to a collection of nearby galaxies that form the Sculptor Group. Other members that have been imaged by ESO telescopes include NGC 55 (eso0914), NGC 253 (eso1025, eso0902) and NGC 7793 (eso0914). Many galaxies have at least some slight peculiarity, but NGC 300 seems to be remarkably normal. This makes it an ideal specimen for astronomers studying the structure and content of spiral galaxies such as our own.

This picture from the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile was assembled from many individual images taken through a large set of different filters with a total exposure time close to 50 hours. The data was acquired over many observing nights, spanning several years. The main purpose of this extensive observational campaign was to take an unusually thorough census of the stars in the galaxy, counting both the number and varieties of the stars, and marking regions, or even individual stars, that warrant deeper and more focused investigation. But such a rich data collection will also have many other uses for years to come. By observing the galaxy with filters that isolate the light coming specifically from hydrogen and oxygen, the many star-forming regions along NGC 300’s spiral arms are shown with particular clarity in this image as red and pink clouds. With its huge field of view, 34 x 34 arcminutes, similar to the apparent size of the full Moon in the sky, the WFI is an ideal tool for astronomers to study large objects such as NGC 300.

NGC 300 is also the home of many interesting astronomical phenomena that have been studied with ESO telescopes. ESO astronomers recently discovered the most distant and one of the most massive stellar-mass black holes yet found (eso1004) in this galaxy, as the partner of a hot and luminous Wolf–Rayet star in a binary system. NGC 300 and another galaxy, NGC 55, are slowly spinning around and towards each other, in the early stages of a lengthy merging process (eso0914). The current best estimate of the distance to the NCG 300 was also determined by astronomers using ESO’s Very Large Telescope at the Paranal Observatory (eso0524), among others.

Photo credit: European Southern Observatory

Ariel

This picture is part of the highest-resolution Voyager 2 imaging sequence of Ariel, a moon of Uranus about 1,300 kilometers (800 miles) in diameter. The clear-filter, narrow-angle image was taken January 24, 1986, from a distance of 130,000 km (80,000 mi). The complexity of Ariel's surface indicates that a variety of geologic processes have occurred. The numerous craters, for example, are indications of an old surface bombarded by meteoroids over a long period. Also conspicuous at this resolution, about 2.4 km (1.5 mi), are linear grooves (evidence of tectonic activity that has broken up the surface) and smooth patches (indicative of deposition of material).

Photo credit: NASA/JPL

Hurricane Earl Multi-Level Winds

The Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra spacecraft captured this image of Hurricane Earl at 15:00 UTC on August 30, 2010. At this time, Hurricane Earl was a Category 3 storm on the Saffir-Simpson scale. The image (left panel) extends approximately 1,110 kilometers (690 miles) in the north-south direction and 380 kilometers (236 miles) in the east-west direction. The hurricane's eye is just visible on the right edge of the MISR image swath.

Winds at various altitudes were obtained by processing the data from five of MISR's nine cameras to produce the display shown on the right. The lengths of the arrows indicate the wind speeds and their orientation shows wind direction. The altitude of a given wind vector is shown in color. Low clouds, less than 4 kilometers (2.5 miles) in altitude (shown in purple), follow the cyclonic (counter-clockwise) flow of air into the hurricane. This warm, moist air is the power source for the hurricane. Mid- and high-level clouds (green and yellow-orange, respectively) move in an anti-cyclonic (clockwise) direction as they flow out from the top of the storm. The very highest clouds with altitudes around 17 kilometers (10.6 miles) are flowing directly away from the eye of the hurricane.

Photo credit: NASA/GSFC/LaRC/JPL, MISR Team

Oslo, Norway

Oslo is the capital and largest city in Norway. Founded in 1048, the city was rebuilt after a disastrous fire in 1648, and re-named Christiania. In 1925, the city reclaimed its original name, Oslo. With the discovery of vast reserves of oil in the North Sea, Norway has become one of the wealthiest countries in the world, and in 2009 Oslo became the world's most expensive city. Oslo's ~900,000 inhabitants live along and at the end of the 60km long Oslofjord. This image was acquired August 26, 2000, covers an area of 35.4 x 41.2 km, and is located at 59.9 degrees north latitude, 10.8 degrees east longitude.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra spacecraft. The instrument was built by Japan's Ministry of Economy, Trade and Industry.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

NGC 4666

The galaxy NGC 4666 takes pride of place at the center of this new image, made in visible light with the Wide Field Imager on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile. NGC 4666 is a remarkable galaxy with very vigorous star formation and an unusual “superwind” of out-flowing gas. It had previously been observed in X-rays by the ESA XMM-Newton space telescope, and the image presented here was taken to allow further study of other objects detected in the earlier X-ray observations.

The prominent galaxy NGC 4666 in the center of the picture is a starburst galaxy, about 80 million light-years from Earth, in which particularly intense star formation is taking place. The starburst is thought to be caused by gravitational interactions between NGC 4666 and its neighboring galaxies, including NGC 4668, visible to the lower left. These interactions often spark vigorous star formation in the galaxies involved.

A combination of supernova explosions and strong winds from massive stars in the starburst region drives a vast flow of gas from the galaxy into space — a so-called “superwind.” The superwind is huge in scale, coming from the bright central region of the galaxy and extending for tens of thousands of light-years. As the superwind gas is very hot it emits radiation mostly as X-rays and in the radio part of the spectrum and cannot be seen in visible light images such as the one presented here.

This image was made as part of a follow-up to observations made with the ESA XMM-Newton space telescope in X-rays. NGC 4666 was the target of the original XMM-Newton observations, but thanks to the telescope’s wide field-of-view many other X-ray sources were also seen in the background. One such serendipitous detection is a faint galaxy cluster seen close to the bottom edge of the image, right of center. This cluster is much further away from us than NGC 4666, at a distance of about three billion light-years.

In order to fully understand the nature of astronomical objects, researchers must study them at several wavelengths. This is because light of different wavelengths can tell us about different physical processes taking place. In this case the Wide Field Imager (WFI) observations were made in visible light to further investigate these serendipitously detected X-ray objects — a good example of how astronomers using different telescopes work together to explore the Universe.

Photo credit: ESO/J. Dietrich

Water Around CW Leonis

The Herschel infrared space observatory has discovered that ultraviolet starlight is the key ingredient for making water in space. It is the only explanation for why a dying star is surrounded by a gigantic cloud of hot water vapor. Herschel is a European Space Agency mission with important participation from NASA.

Every recipe needs a secret ingredient. When astronomers discovered an unexpected cloud of water vapor around the old star IRC+10216, also known as CW Leonis, using NASA's Submillimeter Wave Astronomy Satellite in 2001, they immediately began searching for the source. Stars like IRC+10216 are known as carbon stars and are thought not to make much water. Initially they suspected the star's heat must be evaporating comets or even dwarf planets to produce the water.

Now, Herschel has revealed that the secret ingredient is ultraviolet light, because the water is too hot to have come from the destruction of icy celestial bodies.

"Models predict that there should be no water in the envelopes around stars like this, so astronomers were puzzled about how it got there," said Paul Goldsmith, the NASA project scientist for Herschel at NASA's Jet Propulsion Laboratory, Pasadena, California. "These Herschel observations confirm the surprising presence of water vapor in what we thought was an astronomical desert."

This research, which was led by Leen Decin of the Katholieke Universiteit Leuven, Belgium, appears in the September 2 issue of Nature.

Photo credit: ESA/PACS/SPIRE Consortia

Note: For the ESA press release about this topic, click here: Herschel Detection Explains the Origin of Water in a Carbon Star.

Abell 1758: Cluster Collisions Switch On Radio Halos

This is a composite image of the northern part of the galaxy cluster Abell 1758, located about 3.2 billion light years from Earth, showing the effects of a collision between two smaller galaxy clusters. Chandra X-ray data (blue) reveals hot gas in the cluster and data from the Giant Metrewave Radio Telescope (GMRT) in India (pink) shows huge "halos" generated by ultra-relativistic particles and magnetic fields over vast scales. Optical data from the Digitized Sky Survey are colored gold.

A study of this galaxy cluster and 31 others with Chandra and the GMRT shows that huge radio halos are generated during collisions between galaxy clusters. This result implies that galaxy clusters with radio halos are still forming, while clusters without this radio emission are not still accumulating large amounts of material. The result also implies that relativistic electrons are likely accelerated by turbulence generated by mergers between clusters.

Galaxy clusters are the largest structures in the Universe that are bound together by gravity. They form when smaller clusters or groups of galaxies collide and merge. Collisions between galaxy clusters, such as this one in Abell 1758 and its more famous cousin the Bullet Cluster, are the most energetic events in the Universe since the Big Bang. Their growth rate over the last 7 billion years has been slowed by the effects of dark energy, as shown by previous studies with Chandra.

Photo credit: X-ray (NASA/CXC/SAO/M.Markevitch); Radio (TIFR/GMRTSAO/INAF/R.Cassano, S.Giacintucci); Optical (DSS)

Earth and Moon by Messenger

In the lower left portion of this image, the Earth can be seen, as well as the much smaller Moon to Earth's right. When MESSENGER took this image, a distance of 183 million kilometers (114 million miles) separated the spacecraft and Earth. To provide context for this distance, the average separation between the Earth and the Sun is about 150 million kilometers (93 million miles). Though it is a beautiful, thought-provoking picture, viewing our planet from far away was not the main reason that the mission team planned the collection of this image. Instead, this image was acquired as part of MESSENGER's campaign to search for vulcanoids, small rocky objects that have been postulated to exist in orbits between Mercury and the Sun. Though no vulcanoids have yet been detected, the MESSENGER spacecraft is in a unique position to look for smaller and fainter vulcanoids than has ever before been possible. MESSENGER's vulcanoid searches occur near perihelion passages, when the spacecraft's orbit brings it closest to the Sun. Today is another such perihelion, and MESSENGER is taking a new set of images to search for tiny asteroids lurking close to the Sun.

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Spectrum Analysis of Organic Molecules in the Orion Nebula

The HIFI spectrum of the Orion Nebula, superimposed on a Spitzer image of Orion. A characteristic feature is the spectral richness: among the organic molecules identified in this spectrum are water, carbon monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide, sulphur oxide, sulphur dioxide and their isotope analogues. It is expected that new molecules will also be identified. This spectrum is the first glimpse at the spectral richness of regions of star and planet formation. It harbors the promise of a deep understanding of the chemistry of space once the complete spectral surveys are available.

Image credit: ESA, HEXOS and the HIFI consortium

Notes: HIFI stands for Heterodyne Instrument for the Far Infrared, an instrument on board the Herschel Space Observatory. For more information, see Herschel-HIFI Unveils Precursors of Life-Enabling Molecules in Orion Nebula.