LBN 149.02-00.13

Many consider the shamrock to be a symbol of rebirth and life, making it a fitting symbol for St. Patrick's Day, which happens to occur around the same time as the Spring Equinox in the Northern Hemisphere. It is also fitting that today's image from NASA's Wide-field Infrared Survey Explorer, or WISE, features a region of star birth wrapped in a blanket of dust, colored green in this infrared view. Designated as LBN 149.02-00.13 (or Sh2-205 in the Sharpless catalog of nebulas), this interstellar cloud of dust and gas is a classic example of what astronomers call an HII region, because of all the ionized hydrogen, or HII, within it. Ionized gases carry an electric charge.

This stellar nursery is made up of a shell of ionized gas surrounding a void with an extremely hot, bright star in the middle. With strong stellar winds and intense ultraviolet radiation, the central star -- CY Camelopardalis -- both clears away nearby gas and dust and heats the remaining dust in the shell, causing it to glow in the infrared wavelengths that WISE detected. The dust in the surrounding shell, colored green in this image, is mostly made of polycyclic aromatic hydrocarbon grains, similar to soot. They are warmer in temperature than the more metallic dust grains seen glowing in red around CY Cam. The heavy elements in such dust particles are cooked up in previous generations of stars and then incorporated into the new stars that are born from the cloud. This really is a region of rebirth and life.

Regions very similar to LBN 149.02-00.13 have been featured in previous images, including the LBN 114.55+00.22 (PIA13127), and the LBN 211.91-01.37 (PIA13904) . Like these, LBN 149.02-00.13 can be found along the band of the Milky Way in the night sky, where clouds of gas and dust are much more common. It is located on the outer edge of our local spiral arm (the Orion Arm) about 3,000 light years away. WISE was particularly adept at seeing these types of regions because its infrared detectors were able to pick up light from the nebulae that many other telescopes cannot see.

Scattered throughout the region you can see small clusters of bright red objects, especially near the upper left portion of the image. These are likely "Young Stellar Objects," surrounded by cocoons of dense dust. Young Stellar Objects are stars in their earliest stages of life, just coming together and beginning to start their nuclear fusion. The clouds of gas and dust surrounding each star provide the material from which future planets might possibly form. Perhaps we are seeing the birth of several new planetary systems in this one image alone.

The colors used in this image represent specific wavelengths of infrared light. Blue and cyan (blue-green) 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

Opportunity is Still Smiling

The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter acquired this color image on March 9, 2011, of "Santa Maria" crater, showing NASA's Mars Exploration Rover Opportunity perched on the southeast rim.

The rover is the bluish speck at about the four o'clock position on the crater rim (with indicator arrow on Figure 1). North is up. Rover tracks are visible to the west of the crater.

Opportunity has been studying this relatively fresh, 90-meter-diameter (295-foot-diameter) crater to better understand how crater excavation occurred during the impact and how it has been modified by weathering and erosion since. Note the bright blocks and rays of ejecta surrounding the crater.

Spectral information from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), which is also on the Mars Reconnaissance Orbiter, indicates a hydrated sulfate at this location. Opportunity will soon resume a long-term trek toward a much larger crater, Endeavour. Santa Maria is about 6 kilometers (about 4 miles) from the rim of Endeavour crater, where CRISM indicates both hydrated sulfates as well as phyllosilicates that formed in a wetter past.

This view is one product from the HiRISE observation cataloged as ESP_021536_1780.

Comparisons with earlier HiRISE images of Santa Maria crater (PIA13706 and PIA13754) show the site before and shortly after the rover's arrival.

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

Topography of Sendai, Japan

The topography surrounding Sendai, Japan is well shown in this combined radar image and topographic view generated with data from NASA's Shuttle Radar Topography Mission (SRTM). On March 11, 2011, a magnitude 8.9 earthquake struck offshore about 130 kilometers (80 miles) east of Sendai, the capital city of Japan's Miyagi Prefecture, generating a tsunami that devastated the low-lying coastal city of about 1 million residents.

The city is centered in the image and lies along the coastal plain between the Ohu Mountains and the Pacific Ocean. The eastern part of the city is a low-lying plains area, with the city center being hilly (the city's official elevation is about 43 meters, or 141 feet). Sendai's western areas are mountainous, with its highest point being Mt. Funagata at an elevation of about 1,500 meters (4,921 feet) above sea level.

According to the U.S. Geological Survey, the earthquake occurred as a result of thrust faulting on or near the subduction zone interface plate boundary between the Pacific and North America plates. At the latitude of this earthquake, the Pacific plate moves approximately westwards with respect to the North America plate at a velocity of 83 millimeters per year. The Pacific plate thrusts underneath Japan at the Japan Trench, and dips to the west beneath Eurasia. The location, depth, and focal mechanism of the March 11 earthquake are consistent with the event having occurred as thrust faulting associated with subduction along this plate boundary.

This image combines a radar image acquired in February 2000 during the SRTM mission, and color-coding by topographic height using data from the same mission. Dark green colors indicate low elevations, rising through yellow and tan, to white at the highest elevations.

Location: 38.25 degrees North latitude, 140.85 degrees East longitude
Orientation: North toward the top
Size: approximately 174 by 160 kilometers (108 by 99 miles)
SRTM Data Acquired: February 2000

Image credit: NASA/JPL/NGA

Alpha Camelopardalis and Bow Shock

Just as some drivers obey the speed limit while others treat every road as if it were the Autobahn, some stars move through space faster than others. NASA's Wide-field Infrared Survey Explorer, or WISE, captured this image of the star Alpha Camelopardalis, or Alpha Cam in astronomer-speak, speeding through the sky like a motorcyclist zipping through rush-hour traffic. The supergiant star Alpha Cam is the bright star in the middle of this image, surrounded on one side by an arc-shaped cloud of dust and gas, colored red in this infrared view.

Such fast-moving stars are called runaway stars. The distance and speed of Alpha Cam is somewhat uncertain. It is probably somewhere between 1,600 and 6,900 light-years away and moving at an astonishing rate of somewhere between 680 and 4,200 kilometers per second (between 1.5 and 9.4 million miles per hour). It turns out that WISE is particularly adept at imaging bow shocks from runaway stars. Previous examples can be seen around Zeta Ophiuchi, AE Aurigae, and Menkhib. But Alpha Cam revs things up into a different gear. To put its speed into perspective, if Alpha Cam were a car driving across the United States at 4,200 kilometers per second, it would take less than one second to travel from San Francisco to New York City!

Astronomers believe runaway stars are set into motion either through the supernova explosion of a companion star or through gravitational interactions with other stars in a cluster. Because Alpha Cam is a supergiant star, it gives off a very strong wind. The speed of the wind is boosted in the forward direction the star is moving in space. When this fast-moving wind slams into the slower-moving interstellar material, a bow shock is created, similar to the wake in front of the bow of a ship in water. The stellar wind compresses the interstellar gas and dust, causing it to heat up and glow in infrared. Alpha Cam's bow shock cannot be seen in visible light, but WISE's infrared detectors show us the graceful arc of heated gas and dust around the star.

The red arc of Alpha Cam adds to collection of colorful objects in WISE images taken of the constellation Camelopardalis, or the Giraffe. The gaudily clad giraffe has what looks like a ruby choker above an emerald necklace just to the southeast, as well as an ankle bracelet.

The colors used in this image represent specific wavelengths of infrared light. Stars are seen primarily in blue and cyan (blue-green), because they are emitting light brightly at 3.4 and 4.6 microns. Green represents 12-micron light, primarily emitted by dust. The red of the blow shock represents light emitted at 22 microns.

Photo credit: NASA/JPL-Caltech/UCLA

Virtual Vesta

The animation shows the scientists' best guess to date of what the surface of the protoplanet Vesta might look like. It was created as part of an exercise for NASA's Dawn mission involving mission planners at NASA's Jet Propulsion Laboratory and framing camera team members at the German Aerospace Center (DLR).

The images incorporate the best data on dimples and bulges of the protoplanet Vesta from ground-based telescopes and NASA's Hubble Space Telescope. The topography is color-coded by altitude, with red indicating the highest altitude and blue the lowest. The cratering and small-scale surface variations are computer-generated, based on the patterns seen on the Earth's moon, an inner solar system object with a surface appearance that may be similar to Vesta.

Vesta, located in the main asteroid belt between Mars and Jupiter, formed very early in the history of the solar system and has one of the oldest surfaces in the system. Scientists are eager to get their first close-up look so they can better understand this early chapter.

Dawn science planners have used images like these to ensure optimal images when Dawn gets into orbit around Vesta in July 2011.

Video credit: NASA/JPL-Caltech; text credit: NASA/JPL-Caltech

Note: For more images of Vesta as seen in the above video, see: PIA13768: Virtual Vesta, PIA13769: Simulated Vesta from the South Pole, PIA13770: Model of Vesta, and PIA13890: Anaglyph of Vesta Model.

Carbonates at Huygens Crater

This image shows the context for orbital observations of exposed rocks that had been buried an estimated 5 kilometers (3 miles) deep on Mars. It covers an area about 560 kilometers (350 miles) across, dominated by the Huygens crater, which is about the size of Wisconsin.

The impact that excavated Huygens lifted material from far underground and piled some of it in the crater's rim. At about the 10 o'clock position around the rim of Huygens lies an unnamed crater about 35 kilometers (22 miles) in diameter that has punched into the uplifted rim material and exposed rocks containing carbonate minerals (Figure 1). The minerals were identified by observations with the Compact Reconnaissance Imaging Spectrometer for Mars on NASA's Mars Reconnaissance Orbiter.

North is toward the top of this image, which is centered at 14 degrees south latitude, 304.4 degrees west longitude.

The image combines topographical information from the Mars Orbiter Laser Altimeter instrument on NASA's Mars Global Surveyor with daytime infrared imaging by the Thermal Emission Imaging System camera on NASA's Mars Odyssey orbiter.

Photo credit: NASA/JPL-Caltech/Arizona State University

Sh2-284

NASA's Wide-field Infrared Survey Explorer, or WISE, captured this image of a star-forming cloud of dust and gas located in the constellation of Monoceros. The nebula, commonly referred to as Sh2-284, is relatively isolated at the very end of an outer spiral arm of our Milky Way galaxy. In the night sky, it's located in the opposite direction from the center of the Milky Way.

Perhaps the most interesting features in Sh2-284 are what astronomer call "elephant trunks." Elephant trunks are monstrous pillars of dense gas and dust. The most famous examples of are the "Pillars of Creation," found in an iconic image of the Eagle nebula from NASA's Hubble Space Telescope. In this WISE image, the trunks are seen as small columns of gas stretching towards the center of the void in Sh2-284, like little green fingers with yellow fingernails. The most notable one can be seen on the right side of the void at about the 3 o'clock position. It appears as a closed hand with a finger pointing towards the center of the void. That elephant trunk is about 7 light-years long.

Deep inside Sh2-284 resides an open star cluster, called Dolidze 25, which is emitting vast amounts of radiation in all directions, along with stellar winds. These stellar winds and radiation are clearing out a cavern inside the surrounding gas and dust, creating the void seen in the center. The bright green wall surrounding the cavern shows how far out the gas has been eroded. However, some sections of the original gas cloud were much denser than others, and they were able to resist the erosive power of the radiation and stellar winds. These pockets of dense gas remained and protected the gas "downwind" from them, leaving behind the elephant trunks. These pillars can also be thought of as rising like stalagmites from the cavern walls.

The Sh2-284 nebula is classified as an HII region, as is LBN 114.55+00.22 featured in the September 16, 2010 image. HII regions go hand in hand with star formation, and indeed the stars in the central Dolidze 25 cluster have just recently formed. They're hot, young, bright stars, with ages ranging from 1.5 to 13 million years -- infants by astronomical standards. In comparison, the sun is about 4.6 billion years old.

The colors used in this image represent specific wavelengths of infrared light. Blue and cyan (blue-green) 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

Epic Voyage Through the Universe

This is a rather impressive video featuring different celestial objects within the universe. Can you name them all?

Messier 63 - The Sunflower Galaxy

The various spiral arm segments of the Sunflower galaxy, also known as Messier 63, show up vividly in this image taken in infrared light by NASA's Spitzer Space Telescope. Infrared light is sensitive to the dust lanes in spiral galaxies, which appear dark in visible-light images. Spitzer's view reveals complex structures that trace the galaxy's spiral arm pattern.

Messier 63 is 37 million light-years away -- not far from the well-known Whirlpool galaxy and the associated Messier 51 group of galaxies.

The dust, glowing red in this image, can be traced all the way down into the galaxy's nucleus, forming a ring around the densest region of stars at its center. The dusty patches are where new stars are being born.

The short diagonal line seen on the lower right side of the galaxy's disk is actually a much more distant galaxy, oriented with its edge facing toward us.

Blue shows infrared light with wavelengths of 3.6 and 4.5 microns, green represents 8.0-micron light and red, 24-micron light.

Photo credit: NASA/JPL-Caltech

Note: See also PIA13900: Spitzer's Sunflower Galaxy .

Kizimen Volcano

Kizimen volcano in Kamchatka, Russia is an isolated stratovolcano, with a summit elevation of 2400 m. The summit consists of overlapping lava domes. In the last few months, Kizimen has erupted sporadically, sending eruption plumes as high as 3 km, and drifting more than 170 km. On February 25, a large ash-laden eruption plume can be seen, drifting towards the northeast. Thermal data (red) shows the presence of recent hot block-and-ash flows from summit dome collapses. The data cover an area of 42 x 42km, and are located at 55.2 degrees north latitude, 160.5 degrees east longitude.

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

NGC 247

This image of NGC 247, taken by the Wide Field Imager on the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile, reveals the fine details of this highly inclined spiral galaxy and its rich backdrop. Astronomers say this highly tilted orientation, when viewed from Earth, explains why the distance to this prominent galaxy was previously overestimated.

The spiral galaxy NGC 247 is one of the closest spiral galaxies of the southern sky. In this new view from the Wide Field Imager on the MPG/ESO 2.2-meter telescope in Chile large numbers of the galaxy’s component stars are clearly resolved and many glowing pink clouds of hydrogen, marking regions of active star formation, can be made out in the loose and ragged spiral arms.

NGC 247 is part of the Sculptor Group, a collection of galaxies associated with the Sculptor Galaxy (NGC 253, also shown in eso0902 and eso1025). This is the nearest group of galaxies to our Local Group, which includes the Milky Way, but putting a precise value on such celestial distances is inherently difficult.

To measure the distance from the Earth to a nearby galaxy, astronomers have to rely on a type of variable star called a Cepheid to act as a distance marker. Cepheids are very luminous stars, whose brightness varies at regular intervals. The time taken for the star to brighten and fade can be plugged into a simple mathematical relation that gives its intrinsic brightness. When compared with the measured brightness this gives the distance. However, this method isn’t foolproof, as astronomers think this period–luminosity relationship depends on the composition of the Cepheid.

Another problem arises from the fact that some of the light from a Cepheid may be absorbed by dust en route to Earth, making it appear fainter, and therefore further away than it really is. This is a particular problem for NGC 247 with its highly inclined orientation, as the line of sight to the Cepheids passes through the galaxy’s dusty disc.

However, a team of astronomers is currently looking into the factors that influence these celestial distance markers in a study called the Araucaria Project [1]. The team has already reported that NGC 247 is more than a million light-years closer to the Milky Way than was previously thought, bringing its distance down to just over 11 million light-years.

Apart from the main galaxy itself, this view also reveals numerous galaxies shining far beyond NGC 247. In the upper right of the picture three prominent spirals form a line and still further out, far behind them, many more galaxies can be seen, some shining right through the disc of NGC 247.

This color image was created from a large number of monochrome exposures taken through blue, yellow/green and red filters taken over many years. In addition exposures through a filter that isolates the glow from hydrogen gas have also been included and colored red. The total exposure times per filter were 20 hours, 19 hours, 25 minutes and 35 minutes, respectively.

Photo credit: European Southern Observatory

Note: The Araucaria Project is a collaboration between astronomers from institutions in Chile, the United States and Europe. ESO’s Very Large Telescope provided data for the project.

NGC 6992 - The Veil Nebula

This large mosaic image from NASA's Wide-field Infrared Survey Explorer, or WISE, features the wreckage of an exploded star, as well as other stars nearing the end of their lives. The wispy, colorful arc-shaped features are remnants of the explosion, called a supernova.

Located in the constellation Cygnus, this supernova remnant, called the Veil nebula, was created when a massive star exploded some 5,000 to 8,000 years ago, sending out shock waves that continue to interact with the gas and dust between the stars. This is among the largest of the WISE images featured so far, covering an area equivalent to nearly nine by nine full moons.

The Veil nebula is the name that generally refers to the visible sections of the whole supernova remnant that was seen in its entirety in radio light and called the Cygnus Loop. The portion of the nebula to the right is known as the Witch's Broom nebula. It can be seen in this WISE image as a reddish, long, vertical wispy cloud of dust. The unrelated star 52 Cygni, seen in bright blue, appears to ride the nebula as if a witch on a broom.

The colors of the Veil nebula are the result of shock waves from the supernova energizing the gas and the dust in the region and making it glow across the electromagnetic spectrum. Some astronomers suggest that the Veil nebula represents not one, but two supernova remnants that are interacting with each other.

There are several noteworthy bright stars in the image. The bright yellow star to the left of center is the star UX Cygni, a giant star in the late stages of its life. UX Cygni varies in brightness every 565 days as its surface puffs up and falls back down. Such stars create a large amount of dust in their outer atmospheres as the star moves toward becoming what is called a planetary nebula, a dying star surrounded by its shed layers. The dust surrounding UX Cygni gives it the yellow appearance in this WISE image. Towards the top and a little to the right of the image is a bright cyan star, AM Cygni, which is another variable star nearing the end of its life. On the right edge of the image we see an unidentified bright orange object. It is possibly a red giant star that is also in the last phase of its life, casting off its atmosphere as it becomes a planetary nebula.

Color in this WISE image represents specific wavelengths of infrared light. Blue and cyan (blue-green) represent 3.4-micron and 4.6-micron wavelengths, which is primarily from light emitted from stars. Green and red represent 12-micron and 22-micron wavelengths, which is mainly light from warm dust.

Photo credit:

Protoplanetary Disk Around Star T Chamaeleontis

Using ESO’s Very Large Telescope an international team of astronomers has been able to study the short-lived disc of material around a young star that is in the early stages of making a planetary system. For the first time a smaller companion could be detected that may be the cause of the large gap found in the disc. Future observations will determine whether this companion is a planet or a brown dwarf.

Planets form from the discs of material around young stars, but the transition from dust disc to planetary system is rapid and few objects are caught during this phase [1]. One such object is T Chamaeleontis (T Cha), a faint star in the small southern constellation of Chamaeleon that is comparable to the Sun, but very near the beginning of its life [2]. T Cha lies about 350 light-years from the Earth and is only about seven million years old. Up to now no forming planets have been found in these transitional discs, although planets in more mature discs have been seen before (eso0842, heic0821).

“Earlier studies had shown that T Cha was an excellent target for studying how planetary systems form,” notes Johan Olofsson (Max Planck Institute for Astronomy, Heidelberg, Germany), one of the lead authors of two papers in the journal Astronomy & Astrophysics that describe the new work. “But this star is quite distant and the full power of the Very Large Telescope Interferometer (VLTI) was needed to resolve very fine details and see what is going on in the dust disc.”

The astronomers first observed T Cha using the AMBER instrument and the VLT Interferometer (VLTI) [3]. They found that some of the disc material formed a narrow dusty ring only about 20 million kilometers from the star. Beyond this inner disc, they found a region devoid of dust with the outer part of the disc stretching out into regions beyond about 1.1 billion kilometers from the star.

Nuria Huélamo (Centro de Astrobiología, ESAC, Spain), the lead author of the second paper takes up the story: “For us the gap in the dust disc around T Cha was a smoking gun, and we asked ourselves: could we be witnessing a companion digging a gap inside its protoplanetary disc?”

However, finding a faint companion so close to a bright star is a huge challenge and the team had to use the VLT instrument NACO in a novel and powerful way, called sparse aperture masking, to reach their goal [4]. After careful analysis they found the clear signature of an object located within the gap in the dust disc, about one billion kilometers from the star — slightly further out than Jupiter is within our Solar System and close to the outer edge of the gap. This is the first detection of an object much smaller than a star within a gap in the planet-forming dust disc around a young star. The evidence suggests that the companion object cannot be a normal star [5] but it could be either a brown dwarf [6] surrounded by dust or, most excitingly, a recently formed planet.

Huélamo concludes: “This is a remarkable joint study that combines two different state-of-the-art instruments at ESO’s Paranal Observatory. Future observations will allow us to find out more about the companion and the disc, and also understand what fuels the inner dusty disc.”

Notes:

[1] The transitional discs can be spotted because they give off less radiation at mid-infrared wavelengths. The clearing of the dust close to the star and the creation of gaps and holes can explain this missing radiation. Recently formed planets may have created these gaps, although there are also other possibilities.

[2] T Cha is a T Tauri star, a very young star that is still contracting towards the main sequence.

[3] The astronomers used the AMBER instrument (Astronomical Multi-BEam combineR) and the VLTI to combine the light from all four of the 8.2-meter VLT Unit Telescopes and create a “virtual telescope” 130 meters across.

[4] NACO (or NAOS–CONICA in full) is an adaptive optics instrument attached to ESO’s Very Large Telescope. Thanks to adaptive optics, astronomers can remove most of the blurring effect of the atmosphere and obtain very sharp images. The team used NACO in a novel way, called sparse aperture masking (SAM) to search for the companion. This is a type of interferometry that, rather than combining the light from multiple telescopes as the VLTI does, uses different parts of the mirror of a single telescope (in this case, the mirror of the VLT Unit Telescope 4). This new technique is particularly good for finding faint objects very close to bright ones. VLTI/AMBER is better suited to studying the structure of the inner disc and is less sensitive to the presence of a distant companion.

[5] The astronomers searched for the companion using NACO in two different spectral bands — at around 2.2 microns and at 3.8 microns. The companion is only seen at the longer wavelength, which means that the object is either cool, like a planet, or a dust-shrouded brown dwarf.

[6] Brown dwarfs are objects between stars and planets in size. They are not massive enough to fuse hydrogen in their cores but are larger than giant planets such as Jupiter.

Image credit: ESO/L. Calçada