|
|
Bubbly Little Star
| Title |
Bubbly Little Star |
| Description |
In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive "bubbles." The star is 1,140 light-years away from Earth. The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust. These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material. Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution. This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles. This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red. |
|
HH46/47
| Title |
HH46/47 |
| Description |
This image from NASA's Spitzer Space Telescope transforms a dark cloud into a silky translucent veil, revealing the molecular outflow from an otherwise hidden newborn star. Using near-infrared light, Spitzer pierces through the dark cloud to detect the embedded outflow in an object called HH 46/47. Herbig-Haro (HH) objects are bright, nebulous regions of gas and dust that are usually buried within dark clouds. They are formed when supersonic gas ejected from a forming protostar, or embryonic star, interacts with the surrounding interstellar medium. These young stars are often detected only in the infrared. The Spitzer image was obtained with the infrared array camera. Emission at 3.6 microns is shown as blue, emission from 4.5 and 5.8 microns has been combined as green, and 8.0 micron emission is depicted as red. HH 46/47 is a striking example of a low mass protostar ejecting a jet and creating a bipolar, or two-sided, outflow. The central protostar lies inside a dark cloud (known as a 'Bok globule') which is illuminated by the nearby Gum Nebula. Located at a distance of 1140 light-years and found in the constellation Vela, the protostar is hidden from view in the visible-light image (inset). With Spitzer, the star and its dazzling jets of molecular gas appear with clarity. The 8-micron channel of the infrared array camera is sensitive to emission from polycyclic aromatic hydrocarbons. These organic molecules, comprised of carbon and hydrogen, are excited by the surrounding radiation field and become luminescent, accounting for the reddish cloud. Note that the boundary layer of the 8-micron emission corresponds to the lower right edge of the dark cloud in the visible-light picture. Outflows are fascinating objects, since they characterize one of the most energetic phases of the formation of low-mass stars (like our Sun). The jets arising from these protostars can reach sizes of trillions of miles and velocities of hundreds of thousands miles per hour. Outflows are clear evidence of the presence of a process that creates supersonic beams of gas. This mechanism is tightly bound to the presence of circumstellar discs which surround the young stars. Such discs are likely to contain the materials from which planetary systems form. Our Sun probably underwent a similar process some 4.5 billion years ago. Hence the interest in understanding how quickly and efficiently this mass accretion and loss process takes place in protostars. |
|
HH46/47
| Title |
HH46/47 |
| Description |
This image from NASA's Spitzer Space Telescope transforms a dark cloud into a silky translucent veil, revealing the molecular outflow from an otherwise hidden newborn star. Using near-infrared light, Spitzer pierces through the dark cloud to detect the embedded outflow in an object called HH 46/47. Herbig-Haro (HH) objects are bright, nebulous regions of gas and dust that are usually buried within dark clouds. They are formed when supersonic gas ejected from a forming protostar, or embryonic star, interacts with the surrounding interstellar medium. These young stars are often detected only in the infrared. The Spitzer image was obtained with the infrared array camera. Emission at 3.6 microns is shown as blue, emission from 4.5 and 5.8 microns has been combined as green, and 8.0 micron emission is depicted as red. HH 46/47 is a striking example of a low mass protostar ejecting a jet and creating a bipolar, or two-sided, outflow. The central protostar lies inside a dark cloud (known as a 'Bok globule') which is illuminated by the nearby Gum Nebula. Located at a distance of 1140 light-years and found in the constellation Vela, the protostar is hidden from view in the visible-light image (inset). With Spitzer, the star and its dazzling jets of molecular gas appear with clarity. The 8-micron channel of the infrared array camera is sensitive to emission from polycyclic aromatic hydrocarbons. These organic molecules, comprised of carbon and hydrogen, are excited by the surrounding radiation field and become luminescent, accounting for the reddish cloud. Note that the boundary layer of the 8-micron emission corresponds to the lower right edge of the dark cloud in the visible-light picture. Outflows are fascinating objects, since they characterize one of the most energetic phases of the formation of low-mass stars (like our Sun). The jets arising from these protostars can reach sizes of trillions of miles and velocities of hundreds of thousands miles per hour. Outflows are clear evidence of the presence of a process that creates supersonic beams of gas. This mechanism is tightly bound to the presence of circumstellar discs which surround the young stars. Such discs are likely to contain the materials from which planetary systems form. Our Sun probably underwent a similar process some 4.5 billion years ago. Hence the interest in understanding how quickly and efficiently this mass accretion and loss process takes place in protostars. |
|
HH46/47
| Title |
HH46/47 |
| Description |
This image from NASA's Spitzer Space Telescope transforms a dark cloud into a silky translucent veil, revealing the molecular outflow from an otherwise hidden newborn star. Using near-infrared light, Spitzer pierces through the dark cloud to detect the embedded outflow in an object called HH 46/47. Herbig-Haro (HH) objects are bright, nebulous regions of gas and dust that are usually buried within dark clouds. They are formed when supersonic gas ejected from a forming protostar, or embryonic star, interacts with the surrounding interstellar medium. These young stars are often detected only in the infrared. The Spitzer image was obtained with the infrared array camera. Emission at 3.6 microns is shown as blue, emission from 4.5 and 5.8 microns has been combined as green, and 8.0 micron emission is depicted as red. HH 46/47 is a striking example of a low mass protostar ejecting a jet and creating a bipolar, or two-sided, outflow. The central protostar lies inside a dark cloud (known as a 'Bok globule') which is illuminated by the nearby Gum Nebula. Located at a distance of 1140 light-years and found in the constellation Vela, the protostar is hidden from view in the visible-light image (inset). With Spitzer, the star and its dazzling jets of molecular gas appear with clarity. The 8-micron channel of the infrared array camera is sensitive to emission from polycyclic aromatic hydrocarbons. These organic molecules, comprised of carbon and hydrogen, are excited by the surrounding radiation field and become luminescent, accounting for the reddish cloud. Note that the boundary layer of the 8-micron emission corresponds to the lower right edge of the dark cloud in the visible-light picture. Outflows are fascinating objects, since they characterize one of the most energetic phases of the formation of low-mass stars (like our Sun). The jets arising from these protostars can reach sizes of trillions of miles and velocities of hundreds of thousands miles per hour. Outflows are clear evidence of the presence of a process that creates supersonic beams of gas. This mechanism is tightly bound to the presence of circumstellar discs which surround the young stars. Such discs are likely to contain the materials from which planetary systems form. Our Sun probably underwent a similar process some 4.5 billion years ago. Hence the interest in understanding how quickly and efficiently this mass accretion and loss process takes place in protostars. |
|
Herbig-Haro 46/47
| Title |
Herbig-Haro 46/47 |
| Description |
This 18-second animation zooms in on Herbig-Haro 46/47 and its embedded protostar with molecular outflows. Spitzer/IRAC lifts the cosmic veil and transforms the dark and opaque cloud seen at visible light wavelengths to a spectacular view of a previously unseen protostar and its bipolar outflows. |
|
Lifting the Cosmic Veil
| Title |
Lifting the Cosmic Veil |
| Description |
The first images from the Spitzer Space Telescope, the fourth element of NASA's Great Observatories program. |
|
Vela Pulsar: Chandra Reveals
…
| Name |
Vela Pulsar: Chandra Reveals a Compact Nebula Created by a Shooting Neutron Star |
| Category |
Neutron Stars/X-ray Binaries |
| Release Date |
June 06, 2000 |
|
Vela Pulsar: Wide-Angle View
…
| Name |
Vela Pulsar: Wide-Angle View Of Vela Pulsar |
| Category |
Neutron Stars/X-ray Binaries |
| Release Date |
July 02, 2001 |
|
Vela Pulsar Jet: Firehose-Li
…
| Name |
Vela Pulsar Jet: Firehose-Like Jet Observed In Action |
| Category |
Neutron Stars |
| Release Date |
June 30, 2003 |
|
Supernova Shock Wave Paints
…
| Title |
Supernova Shock Wave Paints Cosmic Portrait |
| General Information |
What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. Back to top [ #top ] |
|
Supernova Shock Wave Paints
…
| Title |
Supernova Shock Wave Paints Cosmic Portrait |
| General Information |
What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. Back to top [ #top ] |
|
Supernova Shock Wave Paints
…
| Title |
Supernova Shock Wave Paints Cosmic Portrait |
| General Information |
What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. Back to top [ #top ] |
|
Supernova Shock Wave Paints
…
| Title |
Supernova Shock Wave Paints Cosmic Portrait |
| General Information |
What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. Back to top [ #top ] |
|
Vela Pulsar: Neutron Star-Ri
…
| Title |
Vela Pulsar: Neutron Star-Ring-Jet |
| Explanation |
This stunning image [ http://chandra.harvard.edu/photo/cycle1/vela/ ] from the orbiting Chandra X-ray Observatory [ http://chandra.harvard.edu/index.html ] is centered on the Vela pulsar -- the collapsed stellar core within the Vela supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/ap960612.html ] some 800 light-years distant. The Vela pulsar is a neutron star [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/ pulsars.html ]. More massive than the Sun, it has the density of an atomic nucleus. About 12 miles in diameter it spins 10 times a second as it hurtles through the supernova debris cloud [ http://antwrp.gsfc.nasa.gov/apod/ap980425.html ]. The pulsar's [ http://www.jb.man.ac.uk/~pulsar/Education/Sounds/ sounds.html ] electric and magnetic fields accelerate particles to nearly the speed of light, powering the compact x-ray [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/ history1_xray.html ] emission nebula revealed in the Chandra picture. The cosmic crossbow shape is over 0.2 light-years across, composed of an arrow-like jet emanating from the polar region of the neutron star [ http://astro.uchicago.edu/home/web/miller/nstar.html ] and bow-like inner and outer arcs believed to be the edges of tilted rings of x-ray emitting high energy particles. Impressively, the swept back compact nebula indicates the neutron star is moving up and to the right in this picture, exactly along the direction of the x-ray jet. The Vela pulsar (and associated supernova remnant [ http://www.seds.org/billa/twn/velax.html ]) was created by a massive star which exploded over 10,000 years ago. Its awesome x-ray rings and jet are reminiscent of another well-known pulsar powered system, the Crab Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap990929.html ]. |
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Gamma-Ray Burst: A Milestone
…
| Title |
Gamma-Ray Burst: A Milestone Explosion |
| Explanation |
Gamma-Ray Bursts (GRBs) were discovered [ http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/grbhist.html ] by accident. Thirty three years ago today, satellites first recorded a GRB [ http://antwrp.gsfc.nasa.gov/htmltest/ jbonnell/www/grbhist.html#firstburst ]. The data plotted here show that the count rate of the satellite gamma-ray instrument abruptly jumped [ http://antwrp.gsfc.nasa.gov/apod/ap991104.html ] indicating a sudden flash of gamma-rays. The Vela satellites [ http://leonardo.jpl.nasa.gov/msl/QuickLooks/velaQL.html ] that detected this and other GRBs were developed to test technology to monitor nuclear test ban treaties [ http://www.state.gov/www/global/arms/treaties/ltbt1.html ]. With on board sensors they watched [ http://antwrp.gsfc.nasa.gov/apod/ap951105.html ] for brief x-ray [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/ history_xray.html ] and gamma-ray [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/ history_gamma.html ] flashes, the telltale signatures of nuclear [ http://www.em.doe.gov/timeline/ ] explosions. As intended, the Velas found flashes of gamma-rays - but not from nuclear detonations near Earth. Instead, the flashes were determined to come from deep space! Dubbed "cosmic gamma-ray bursts" [ http://antwrp.gsfc.nasa.gov/apod/ap961123.html ] they are now known [ http://antwrp.gsfc.nasa.gov/diamond_jubilee/ debate_1995.html ] to be the most powerful explosions originating in distant galaxies. What could power a gamma-ray burst [ http://www.sciam.com/0797issue/ 0797fishman.html ]? |
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ROSAT Explores The X-Ray Sky
| Title |
ROSAT Explores The X-Ray Sky |
| Explanation |
Launched in 1990, the orbiting ROSAT observatory [ http://heasarc.gsfc.nasa.gov/docs/rosat/rosat.html ] explored the Universe by viewing the entire sky in x-rays [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/ history1_xray.html ] -- photons with about 1,000 times more energy than visible light. This ROSAT survey [ http://www.xray.mpe.mpg.de/rosat/survey/sxrb/12/ass.html ] produced the sharpest, most sensitive image of the x-ray sky to date. The all-sky image is shown with the plane of our Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap980523.html ] running horizontally through the center. Both x-ray brightness and relative energy are represented with red, green, and blue colors indicating three x-ray energy ranges (from lowest to highest). Bright x-ray spots near the galactic plane are within our own Milky Way. The brightest region (right of center) is toward the Vela Pulsar [ http://antwrp.gsfc.nasa.gov/apod/ap000609.html ] and the Puppis supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/ap991209.html ]. Bright sources beyond our Galaxy are also apparent, notably the Virgo cluster of galaxies [ http://www.seds.org/messier/more/virgo.html ] (near top right) and the Large Magellanic Cloud (LMC) [ http://www.seds.org/messier/xtra/ngc/lmc.html ]. The LMC is easy to find here as several of the black stripes (blank areas caused by missing data) seem to converge on its position (lower right). Over large areas of the sky a general diffuse background of x-rays [ http://chandra.harvard.edu/press/00_releases/ press_011400bg.html ] dominates. Hot gas in our own Galaxy provides much of this background and gives rise to the grand looping structures [ http://antwrp.gsfc.nasa.gov/apod/ap990503.html ] visible in the direction of the galactic center (image center). Unresolved extragalactic sources also add to this background, particularly above and below the plane. Despite the x-ray sky's exotic appearance, a very familiar feature is visible - the gas and dust clouds which line the plane of our galaxy absorb x-rays as well as optical light and produce the dark bands running through the galactic center [ http://antwrp.gsfc.nasa.gov/apod/ap000629.html ]. |
|
Vela Supernova Remnant in Vi
…
| Title |
Vela Supernova Remnant in Visible Light |
| Explanation |
The explosion is over but the consequences continue. About eleven thousand years ago a star in the constellation of Vela [ http://www.hawastsoc.org/deepsky/vel/index.html ] could be seen to explode [ http://www.youtube.com/watch?v=gL1xUWgBlFw ], creating a strange point of light briefly visible to humans living near the beginning of recorded history [ http://en.wikipedia.org/wiki/Cave_painting ]. The outer layers of the star crashed into the interstellar medium [ http://antwrp.gsfc.nasa.gov/apod/ap020210.html ], driving a shock wave [ http://antwrp.gsfc.nasa.gov/apod/ap020313.html ] that is still visible today. A roughly spherical, expanding shock wave is visible in X-rays [ http://antwrp.gsfc.nasa.gov/apod/ap960612.html ]. The above image [ http://www.skyfactory.org/vela/vela.htm ] captures much of that filamentary and gigantic shock in visible light [ http://imagers.gsfc.nasa.gov/ems/visible.html ], spanning almost 100 light years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] and appearing twenty times the diameter of the full moon [ http://antwrp.gsfc.nasa.gov/apod/ap051113.html ]. As gas flies away from the detonated star, it decays [ http://imagine.gsfc.nasa.gov/docs/features/exhibit/cgro_snr.html ] and reacts with the interstellar medium, producing light in many different colors and energy bands. Remaining at the center of the Vela Supernova Remnant [ http://en.wikipedia.org/wiki/Vela_Supernova_Remnant ] is a pulsar [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html ], a star as dense as nuclear matter that completely rotates more than ten times in a single second. |
|
Pulsar Wind in the Vela Nebu
…
| Title |
Pulsar Wind in the Vela Nebula |
| Explanation |
The Vela pulsar was born [ http://antwrp.gsfc.nasa.gov/apod/ap980425.html ] 10,000 years ago at the center of a supernova -- an exploding star [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/ supernovae.html ]. In this Chandra Observatory x-ray image [ http://chandra.harvard.edu/photo/cycle1/velawv/ index.html ], the pulsar still produces a glowing nebula at the heart of the expanding cloud of stellar debris. The pulsar [ http://www.jb.man.ac.uk/~pulsar/Education/Sounds/ sounds.html ] itself is a neutron star [ http://heasarc.gsfc.nasa.gov/docs/objects/binaries/ neutron_star_structure.html ], formed as the stellar core was compacted [ http://observe.ivv.nasa.gov/nasa/space/stellardeath/ stellardeath_3a.html ] to nuclear densities. With a strong magnetic field, approximately the mass of the Sun, and a diameter of about 20 kilometers, the Vela pulsar rotates 11 times "a second". The sharp Chandra image aids astronomers [ http://xxx.lanl.gov/abs/astro-ph/0105128 ] in understanding such extreme systems as efficient high-voltage generators [ http://chandra.harvard.edu/chronicle/0201/vela.html ] which drive structured winds [ http://antwrp.gsfc.nasa.gov/apod/ap000609.html ] of electrically charged particles. An x-ray bright nebula is created as the pulsar winds slam into the surrounding material. This view spans about 6 light-years across the central region of the much larger Vela supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/ap960612.html ]. |
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Vela Satellites: The Watcher
…
| Title |
Vela Satellites: The Watchers |
| Explanation |
In October of 1963 the US Air Force [ http://www.dtic.dla.mil/airforcelink/ ] launched the first in a series of satellites inspired by a recently signed nuclear test ban treaty [ gopher://wealaka.okgeosurvey1.gov/11/nuke.treaties ]. Signatories of this treaty agreed not to test nuclear devices in the atmosphere or in space. These "Vela" (from the Spanish verb [ http://www.willamette.edu/~tjones/Language-Page.html ] velar, to watch) satellites were part of an unclassified program whose goal was to develop the technology to monitor nuclear tests from space. A Vela satellite [ http://heasarc.gsfc.nasa.gov/docs/heasarc/missions/vela5a.html ] is pictured above in an artist's conception, keeping watch over the Earth. The high energy radiation sensors onboard the Velas did not detect any clandestine nuclear explosions [ http://www.pal.xgw.fi/hew/ ]. Instead, in the most surprising discovery [ http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/grbhist.html ] in the history of space based astronomy, they found bursts of gamma rays [ http://antwrp.gsfc.nasa.gov/apod/ap950827.html ] coming from deep space! The mysterious origin of these brief, intense flashes of gamma rays is one of the most hotly debated topics [ http://antwrp.gsfc.nasa.gov/diamond_jubilee/debate.html ] in modern astrophysics. |
|
Star-Forming Region RCW38 fr
…
| Title |
Star-Forming Region RCW38 from 2MASS |
| Explanation |
The star cluster in RCW38 was hiding. Looking at the star forming region [ http://antwrp.gsfc.nasa.gov/apod/stellar_nurseries.html ] RCW38 [ http://www.ipac.caltech.edu/2mass/gallery/showcase/rcw38/caption.html ] will not normally reveal most of the stars in this cluster. The reason is that the open cluster [ http://antwrp.gsfc.nasa.gov/apod/open_clusters.html ] is so young that it is still shrouded in thick dust [ http://antwrp.gsfc.nasa.gov/apod/ap990509.html ] that absorbs visible light. This dust typically accompanies the gas that condenses to form young stars. When viewed in infrared [ http://www.ipac.caltech.edu/Outreach/Edu/infrared.html ] light, however, many stars in RCW38 are revealed, because dust is less effective at absorbing infrared light. The above representative-color image [ http://www.ipac.caltech.edu/2mass/gallery/showcase/rcw38/index.html ] mosaic of RCW38 taken by the 2MASS sky survey [ http://www.ipac.caltech.edu/2mass/overview/about2mass.html#about ] in infrared light shows not only many bright blue stars from the star cluster but clouds of brightly emitting gas [ http://antwrp.gsfc.nasa.gov/apod/emission_nebulae.html ] and dramatic lanes of dark dust. RCW38 [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1987MNRAS.228..721M ] spans about 10 light-years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] and is located about 5500 light years away towards the constellation [ http://www.astro.wisc.edu/~dolan/constellations/extra/constellations.html ] of Vela [ http://www.astronomical.org/constellations/vel.html ]. |
|
X-Ray Mystery in RCW 38
| Title |
X-Ray Mystery in RCW 38 |
| Explanation |
A mere 6,000 light-years distant and sailing through the constellation Vela [ http://www.hawastsoc.org/deepsky/vel/index.html ], star cluster RCW 38 [ http://antwrp.gsfc.nasa.gov/apod/ap020717.html ] is full of powerful stars. It's no surprise that these stars, only a million years young with hot outer atmospheres, appear as [ http://antwrp.gsfc.nasa.gov/apod/ap990828.html ] point-like x-ray sources dotting this x-ray image [ http://chandra.harvard.edu/photo/2002/rcw38/index.html ] from the orbiting Chandra Observatory [ http://chandra.harvard.edu/about/axaf_mission.html ]. But the diffuse cloud of x-rays surrounding them is a bit mysterious. The image is color coded by x-ray energy, with high energies in blue, medium in green, and low energy x-rays in red. Just a few light-years across, the cloud which pervades the cluster has colors suggesting the x-rays [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/ history_xray.html ] are produced by high energy electrons moving through magnetic fields [ http://chandra.harvard.edu/xray_astro/xrays3.html ]. Yet a source of energetic electrons, such as shockwaves from exploding stars (supernova remnants [ http://chandra.harvard.edu/xray_sources/ supernovas.html ]), or rotating neutron stars (pulsars), is not apparent in the Chandra data. Whatever their origins, the energetic particles could leave an imprint on planetary systems forming in young star cluster RCW 38, just as nearby energetic [ http://www.pbs.org/wgbh/nova/gamma/ milkyway.html ] events seem to have affected the chemistry and isotopes found in our own solar system [ http://www.psrd.hawaii.edu/Mar00/ supernovaDebris.html ]. |
|
Vela Supernova Remnant in X-
…
| Title |
Vela Supernova Remnant in X-ray |
| Explanation |
What happens when a star explodes? [ http://lheawww.gsfc.nasa.gov/users/jonathan/outreach_pages/supernova.html ] A huge fireball of hot gas [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ] shoots out in all directions. When this gas slams into the existing interstellar medium [ http://lsnt7.lightspeed.net/astronomy/ismnotes/ismnotes.html ], it heats up so much it glows in X-rays [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#X-ray ]. The above picture [ http://heasarc.gsfc.nasa.gov/Images/rosat/rosat08.html ] by the ROSAT satellite [ http://heasarc.gsfc.nasa.gov/docs/heasarc/missions/rosat.html ] has captured some of these X-rays and shown -- for the first time -- the Vela supernova explosion [ http://www.seds.org/billa/twn/velax.html ] was roughly spherical. Non-uniformity of the interstellar medium causes Vela's appearance to be irregular. [ http://adsabs.harvard.edu/cgi-bin/nph-article_query?bibcode=1994ApJ...437..209B&type=SCREEN_VIEW&data_type=GIF&page=1&db_key=AST ] The size of this X-ray emitting spherical shell is immense - 230 light years across, covering over 100 times the sky-area of the full Moon. The supernova [ http://antwrp.gsfc.nasa.gov/apod/lib/supernova.html ] that created this nebula occurred about 1500 light years away and about 11,000 years ago. Coincidently, a completely different supernova [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/msblues.html ] shell can also be seen in X-rays in this picture! It is visible as the bright patch near the upper right. This Puppis supernova remnant [ http://lheawww.gsfc.nasa.gov/users/jonathan/outreach_pages/neutron_stars.html ] nebula is actually about four times farther than the Vela nebula. |
|
ROSAT Explores the X-Ray Sky
| Title |
ROSAT Explores the X-Ray Sky |
| Explanation |
Launched in 1990, the orbiting ROSAT observatory [ http://legacy.gsfc.nasa.gov/docs/heasarc/missions/rosat.html ] explored the Universe by viewing the entire sky in x-rays [ http://heasarc.gsfc.nasa.gov/docs/learning_center/ basic/xray/xray_information.html ] - photons with about 1,000 times more energy than visible light [ http://heasarc.gsfc.nasa.gov/docs/learning_center/ basic/emspectrum.html ]. This ROSAT survey [ http://www.rosat.mpe-garching.mpg.de/survey/sxrb/ ] produced the sharpest, most sensitive image of the x-ray sky to date. The all-sky image is shown with the plane of our Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap960213.html ] running horizontally through the center. Both x-ray brightness and relative energy are represented with red, green, and blue colors indicating three x-ray energy ranges (from lowest to highest). Bright x-ray spots near the galactic plane are within our own Milky Way. The brightest region (right of center) is toward the Vela Pulsar and the Puppis supernova remnant [ http://lheawww.gsfc.nasa.gov/users/jonathan/outreach_pages/ neutron_stars.html ]. Bright sources beyond our Galaxy are also apparent, notably the Virgo cluster of galaxies [ http://antwrp.gsfc.nasa.gov/apod/ap960419.html ] (near top right) and the Large Magellanic Cloud (LMC) [ http://antwrp.gsfc.nasa.gov/apod/ap950918.html ]. The LMC is easy to find here as several of the black stripes (blank areas caused by missing data) seem to converge on its position (lower right). Over large areas of the sky a general diffuse background of x-rays dominates [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ%2E%2E%2E454%2E%2E643S&db_key=AST ]. Hot gas in our own Galaxy provides much of this background and gives rise to the grand looping structures visible in the direction of the galactic center (image center). Unresolved extragalactic sources also add to this background, particularly above and below the plane. Despite the x-ray sky's exotic appearance, a very familiar feature is visible - the gas and dust clouds which line the plane of our galaxy absorb x-rays as well as optical light and produce the dark bands running through the galactic center [ http://antwrp.gsfc.nasa.gov/apod/ap960605.html ]. |
|
The Gum Nebula Supernova Rem
…
| Title |
The Gum Nebula Supernova Remnant |
| Explanation |
Because the Gum Nebula is the closest supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/supernova_remnants.html ], it is actually hard to see. Spanning 40 degrees [ http://math.rice.edu/~pcmi/sphere/drg_txt.html ] across the sky, the nebula is so large and faint [ http://antwrp.gsfc.nasa.gov/apod/ap020217.html ] it is easily lost in the din of a bright and complex background. The Gum Nebula [ http://www.southernskyphoto.com/southern_sky/gum_nebula.htm ], highlighted nicely in the above wide angle photograph [ http://www.celestialimage.com/page107.html ], is so close that we are much nearer the front edge than the back edge, each measuring 450 and 1500 light years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] respectively. The complex nebula [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1993A%26A...280..231S ] lies in the direction of the constellations [ http://www.dibonsmith.com/stars.htm ] of Puppis [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Puppis.html ] and Vela [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Vela.html ]. Oddly, much remains unknown about the Gum Nebula [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001MNRAS.325.1213W ], including the timing and even number of supernova explosions [ http://heasarc.gsfc.nasa.gov/docs/snr.html ] that formed it. |
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The Pencil Nebula Supernova
…
| Title |
The Pencil Nebula Supernova Shockwave |
| Explanation |
At 500,000 kilometers per hour, a supernova [ http://heasarc.gsfc.nasa.gov/docs/snr.html ] shockwave [ http://www.sciam.com/article.cfm?articleID=0004A908-9AAC-1CDC-B4A8809EC588EEDF ] plows through interstellar space. This shockwave is known as the Pencil Nebula [ http://www.ast.cam.ac.uk/AAO/images/captions/aat084.html ], or NGC 2736, and is part of the Vela supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/ap960612.html ], an expanding shell of a star that exploded about 11,000 years ago. Initially the shockwave [ http://heritage.stsci.edu/2003/16/caption.html ] was moving at millions of kilometers per hour, but the weight of all the gas it has swept up has slowed it considerably. Pictured above [ http://hubblesite.org/newscenter/archive/2003/16/image/a ], the shockwave [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003ApJ...589..242S ] moves from left to right, as can be discerned by the lack of gas on the left. The above region [ http://heritage.stsci.edu/2003/16/fast_facts.html ] spans nearly a light year [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] across, a small part of the 100+ light-year span of the entire Vela supernova remnant [ http://antwrp.gsfc.nasa.gov/apod/ap990803.html ]. The Hubble Space Telscope [ http://antwrp.gsfc.nasa.gov/apod/ap010806.html ] ACS [ http://acs.pha.jhu.edu/ ] captured the above image last October. |
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Gamma-Ray Burst: A Milestone
…
| Title |
Gamma-Ray Burst: A Milestone Explosion |
| Explanation |
Gamma-Ray Bursts (GRBs) were discovered [ http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/grbhist.html ] by accident. In fact, GRBs [ http://antwrp.gsfc.nasa.gov/apod/ap970625.html ] always seem to be where scientists least expect them. Thirty years ago today, satellites first recorded a GRB [ http://antwrp.gsfc.nasa.gov/htmltest/ jbonnell/www/grbhist.html#firstburst ]. The burst data plotted in this histogram [ http://www.stat.ufl.edu/~hyper/Sections/lect2/node17.html ] show that the count rate of the gamma-ray instrument abruptly jumped indicating a sudden flash of gamma-rays. The Vela satellites [ http://antwrp.gsfc.nasa.gov/apod/ap951105.html ] that detected this and other GRBs were developed to test technology to monitor nuclear test ban treaties [ gopher://wealaka.okgeosurvey1.gov:70/00/nuke.treaties/LTBT ]. With on board sensors they watched for brief X-ray and gamma-ray [ http://heasarc.gsfc.nasa.gov/docs/ learning_center/basic/emspectrum.html ] flashes, the telltale signs of nuclear explosions from the vicinity of the Earth [ gopher://wealaka.okgeosurvey1.gov:70/11/nuke.cat ]. As intended, the Velas found flashes of gamma-rays - but not from nuclear detonations near Earth. Instead, the flashes came from deep space! Dubbed "cosmic gamma-ray bursts" [ http://antwrp.gsfc.nasa.gov/apod/ap961123.html ] their origin was then unknown and is still controversial [ http://antwrp.gsfc.nasa.gov/diamond_jubilee/debate_1995.html ]. However, the gamma-ray surprises were not over. Exploring the high-energy sky [ http://antwrp.gsfc.nasa.gov/apod/ap970222.html ] nearly 25 years later, the orbiting Compton Observatory's Burst and Transient Source Experiment (BATSE) [ http://www.batse.msfc.nasa.gov/astronomy/batse/harmon_allsky.html ], intentionally designed to detect cosmic gamma-ray bursts [ http://www.batse.msfc.nasa.gov/data/grb/skymap/ ], was searching for clues to the GRB mystery. But the second burst BATSE recorded did not come from deep space. It came from near the Earth! Don't worry, these terrestrial GRBs are not nuclear bombs exploding. They are a new phenomenon now thought [ http://www.batse.msfc.nasa.gov/astronomy/fishman_tgf.html ] to be related to a recently discovered type of high altitude lightning [ http://antwrp.gsfc.nasa.gov/apod/ap951111.html ]. Exploring new horizons continues to yield unexpected results. [ http://antwrp.gsfc.nasa.gov/apod/ap960915.html ] |
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Vela Supernova Remnant in Op
…
| Title |
Vela Supernova Remnant in Optical Credit: Photograph made from plates taken with the UK Schmidt Telescope [ http://www.roe.ac.uk/ukstu/ukst.html ]. Color photography by David Malin. Copyright: Anglo-Australian Telescope Board [ http://www.aao.gov.au/images.html ] |
| Explanation |
About 11,000 years ago a star in the constellation of Vela [ http://galileo.gmu.edu/constellation/VEL.html ] exploded. This bright supernova [ http://antwrp.gsfc.nasa.gov/apod/lib/supernova.html ] may have been visible to the first human farmers. Today the Vela supernova remnant [ http://www.seds.org/billa/twn/velax.html ] marks the position of a relatively close and recent explosion in our Galaxy [ http://antwrp.gsfc.nasa.gov/apod/lib/milky_way.html ]. A roughly spherical, expanding shock wave is visible in X-rays [ http://antwrp.gsfc.nasa.gov/apod/ap960611.html ]. In the above optical photograph, the upper left corner of the spherical blast wave is shown in detail. As gas flies away from the detonated star [ http://lheawww.gsfc.nasa.gov/users/jonathan/outreach_pages/supernova.html ], it reacts with the interstellar medium [ http://www-dapnia.cea.fr/Phys/Sap/Report/interstellar_medium.html ], knocking away closely held electrons from even heavy elements [ http://pdg.lbl.gov/cpep/adventure.html ]. When the electrons recombine with these atoms [ http://adsabs.harvard.edu/cgi-bin/nph-article_query?bibcode=1995ApJ%2E%2E%2E440%2E%2E227J&page=1&plate_select=NO&type=GIF ], light in many different colors and energy bands [ http://heasarc.gsfc.nasa.gov/docs/learning_center/basic/emspectrum.html ] is produced. |
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Runaway Star
| Title |
Runaway Star |
| Explanation |
Runaway stars are massive stars [ http://www.eso.org/outreach/press-rel/pr-1997/pr-01-97.html ] traveling rapidly through interstellar space. Like a ship plowing through the interstellar medium [ http://antwrp.gsfc.nasa.gov/apod/ap961218.html ], runaway star HD 77581 has produced this graceful arcing bow wave or "bow shock" - compressing the gaseous material in its path. Located near the centre of this European Southern Observatory photograph [ http://www.eso.org/outreach/press-rel/pr-1997/phot-02-97.html ], HD 77581 itself is so bright that it saturates the sensitive camera and produces the spiky cross shape. This star is over 6,000 light-years away in the constellation Vela [ http://www.astro.wisc.edu/~dolan/constellations/ constellations/Vela.html ], and appears to move at over 50 miles per second. What force could set this star in motion [ http://www.aas.org/meetings/aas184/abs/S601.html ]? A clue to the answer may lie in its optically invisible companion star, an X-ray bright [ http://antwrp.gsfc.nasa.gov/apod/ap961008.html ] pulsar [ http://antwrp.gsfc.nasa.gov/apod/ap960531.html ] known as Vela X-1. This pulsar [ http://crazyhorse.msfc.nasa.gov/data/pulsar/sources/velax1nml.html ] is clearly the remnant of a supernova explosion [ http://legacy.gsfc.nasa.gov/docs/snr.html ] ... which seems to have given this massive star and its companion a mighty kick [ http://antwrp.gsfc.nasa.gov/apod/ap970225.html ]! |
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X-Ray Mystery in RCW 38
| Title |
X-Ray Mystery in RCW 38 |
| Explanation |
A mere 6,000 light-years distant and sailing through the constellation Vela [ http://www.hawastsoc.org/deepsky/vel/index.html ], star cluster RCW 38 [ http://antwrp.gsfc.nasa.gov/apod/ap020717.html ] is full of powerful stars. It's no surprise that these stars, only a million years young with hot outer atmospheres, appear as [ http://antwrp.gsfc.nasa.gov/apod/ap990828.html ] point-like x-ray sources dotting this x-ray image [ http://chandra.harvard.edu/photo/2002/rcw38/index.html ] from the orbiting Chandra Observatory [ http://chandra.harvard.edu/ ]. But the diffuse cloud of x-rays surrounding them is a bit mysterious. The image is color coded by x-ray energy, with high energies in blue, medium in green, and low energy x-rays in red. Just a few light-years across, the cloud which pervades the cluster has colors suggesting the x-rays [ http://imagine.gsfc.nasa.gov/docs/science/know_l2/ history_xray.html ] are produced by high energy electrons moving through magnetic fields [ http://chandra.harvard.edu/xray_astro/xrays3.html ]. Yet a source of energetic electrons, such as shockwaves from exploding stars (supernova remnants [ http://chandra.harvard.edu/xray_sources/ supernovas.html ]), or rotating neutron stars (pulsars [ http://imagine.gsfc.nasa.gov/docs/science/ know_l1/pulsars.html ]), is not apparent in the Chandra data. Whatever their origins, the energetic particles could leave an imprint on planetary systems forming in young star cluster RCW 38, just as nearby energetic [ http://www.pbs.org/wgbh/nova/gamma/ milkyway.html ] events seem to have affected the chemistry and isotopes found in our own solar system [ http://www.psrd.hawaii.edu/Mar00/ supernovaDebris.html ]. |
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Ring Around the Galaxy
| Title |
Ring Around the Galaxy |
| Explanation |
It is difficult to hide one galaxy far behind another. The closer galaxy's gravity will act like a huge lens [ http://imagine.gsfc.nasa.gov/docs/features/news/grav_lens.html ], pulling images of the background galaxy around both sides. This is just the case observed in the above recently released image [ http://www.eso.org/outreach/press-rel/pr-1998/pr-20-98.html ] from the VLT [ http://antwrp.gsfc.nasa.gov/apod/ap960901.html ]: the red galaxy in the middle is in the foreground, lensing the image of the background green galaxy into surrounding contorted arcs [ http://antwrp.gsfc.nasa.gov/apod/ap981102.html ]. These images are more than sideshow [ http://vela.astro.ulg.ac.be/themes/extragal/gravlens/bibdat/engl/DE/DE106/didac106.html ]s, since the distance between background images increases [ http://vela.astro.ulg.ac.be/themes/extragal/gravlens/bibdat/engl/DE/DE103/didac103.html ] with the mass of the lens. This lens mass turns out to be much greater than the sum of all its stars - indicating the presence of dark matter [ http://www.sciam.com/specialissues/0398cosmos/0398rubin.html ]. The distorted galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap980614.html ] is said to appear as an Einstein ring [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/nslens_effects.html ], named after Albert Einstein [ http://antwrp.gsfc.nasa.gov/apod/ap980927.html ] who accurately predicted many attributes of the gravitational lens effect [ http://vela.astro.ulg.ac.be/themes/extragal/gravlens/bibdat/engl/index.html ] -- although he also guessed that such an effect was unlikely to be seen in practice. |
|
A Gallery of Gravitational M
…
| Title |
A Gallery of Gravitational Mirages |
| Explanation |
The deeper you peer into the universe, the harder it is to see straight. The reason is that distant galaxies act as gravitational lenses [ http://vela.astro.ulg.ac.be/themes/extragal/gravlens/bibdat/engl/index.html ], deflecting light that passes nearby. These deflections result in the distortion of background sources [ http://antwrp.gsfc.nasa.gov/apod/ap980614.html ], and in some cases the creation of multiple images [ http://antwrp.gsfc.nasa.gov/apod/ap990331.html ]. Pictured above [ http://oposite.stsci.edu/pubinfo/pr/1999/18/index.html ], candidate artifacts of gravitational lensing [ http://imagine.gsfc.nasa.gov/docs/features/news/grav_lens.html ] have been found [ http://xxx.lanl.gov/abs/astro-ph/9902100 ] in images from the Medium Deep Survey [ http://archive.stsci.edu/mds/index.html ] being done with the Hubble Space Telescope [ http://www.stsci.edu/hst/ ]. Background source images that are lensed [ http://science.nasa.gov/newhome/headlines/ast14may99_1.htm ] by foreground galaxies include quasars, appearing as multiple blue smudges [ http://antwrp.gsfc.nasa.gov/apod/ap951220.html ], and galaxies, distorted into curving arcs [ http://antwrp.gsfc.nasa.gov/apod/ap981223.html ]. Unusual and interesting candidates [ http://oposite.stsci.edu/pubinfo/pr/1999/18/extra-photos.html ] for gravitational lensing include an edge-on galaxy disk [ http://antwrp.gsfc.nasa.gov/apod/ap981220.html ] which might be acting as a lens (upper left) and an image nicknamed London Underground [ http://www.jle.lul.co.uk/ ] (far left) which could well be the distortion of a background galaxy into an optical Einstein ring [ http://antwrp.gsfc.nasa.gov/apod/ap981102.html ]. |
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The Vela Supernova Remnant E
…
| Title |
The Vela Supernova Remnant Expands |
| Explanation |
The explosion is over but the consequences continue. About eleven thousand years ago a star in the constellation of Vela [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Vela.html ] exploded, creating a strange point of light [ http://www.aao.gov.au/local/www/dfm/uks002.html ] briefly visible to humans living near the beginning of recorded history [ http://warrensburg.k12.mo.us/ew/human.html ]. The outer layers of the star crashed into the interstellar medium [ http://spacsun.rice.edu/~twg/lism.html ], driving a shock wave [ http://www.fireplug.net/~rshand/streams/vela/vela.html ] that is still visible today [ http://antwrp.gsfc.nasa.gov/apod/ap970713.html ]. Different colors in the complex, right moving shock, pictured on the left [ http://www.aao.gov.au/local/www/dfm/aat078.html ], represent different energies [ http://antwrp.gsfc.nasa.gov/apod/ap960612.html ] of impact of the shock front [ http://www.aao.gov.au/local/www/dfm/aat084.html ]. The star on the left appears by chance in the foreground, and the long diagonal line is also unrelated. Remaining at the center of the Vela Supernova Remnant [ http://www.seds.org/billa/twn/velax.html ] is a pulsar [ http://antwrp.gsfc.nasa.gov/apod/ap990803.html http://universe.gsfc.nasa.gov/videos/millisecond.html ], a star as dense as nuclear matter [ http://user88.lbl.gov/NSD_docs/abc/home.html ] that completely rotates more than ten times in a single second. |
|
Runaway Star
| Title |
Runaway Star |
| Explanation |
Runaway stars are massive stars [ http://www.eso.org/outreach/press-rel/pr-1997/pr-01-97.html ] traveling rapidly through interstellar space. Like a ship plowing through the interstellar medium [ http://antwrp.gsfc.nasa.gov/apod/ap961218.html ], runaway star HD 77581 has produced this graceful arcing bow wave or "bow shock" - compressing the gaseous material in its path. Located near the centre of this European Southern Observatory photograph [ http://www.eso.org/outreach/press-rel/pr-1997/phot-02-97.html ], HD 77581 itself is so bright that it saturates the sensitive camera and produces the spiky cross shape [ http://antwrp.gsfc.nasa.gov/apod/ap971119.html ]. This star is over 6,000 light-years away in the constellation Vela [ http://www.astro.wisc.edu/~dolan/constellations/ constellations/Vela.html ], and appears to move at over 50 miles per second. What force could set this star in motion? A clue to the answer may lie in its optically invisible companion star, an X-ray bright [ http://chandra.harvard.edu/ ] pulsar [ http://antwrp.gsfc.nasa.gov/apod/ap980905.html ] known as Vela X-1. This pulsar is clearly the remnant of a supernova explosion [ http://legacy.gsfc.nasa.gov/docs/snr.html ] ... which seems to have given this massive star and its companion a mighty kick [ http://antwrp.gsfc.nasa.gov/apod/ap990515.html ]! |
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![Vela Supernova Remnant in Optical Credit: Photograph made from plates taken with the UK Schmidt Telescope [ http://www.roe.ac.uk/ukstu/ukst.html ]. Color photography by David Malin. Copyright: Anglo-Australian Telescope Board [ http://www.aao.gov.au/images.html ]](http://mm04.nasaimages.org/MediaManager/srvr?mediafile=/Size1/NVA2-4-NA/8325/vela_roe.jpg&userid=1&username=admin&resolution=1&servertype=JVA&cid=4&iid=NVA2&vcid=NA&usergroup=NASA_Astronomy_Picture_of_the_Day_Collecti-4-Admin&profileid=16)
