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Hubble Heritage Archive - 2002 Hubble Heritage Archive: 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 Gemini | Apollo | Hubble Space Telescope
Hubble Heritage Picture - January 2002
These globules, first identified by astronomer A.D. Thackeray in 1950, float in this very active star-forming region. Globules like these were first identified by Dutch-American astronomer Bart Bok in 1947, but little was known about them except that they are associated with large areas of star formation, known as "HII regions" due to the high concentrations of hydrogen gas. The high resolution offered by the HST allows astronomers to study these in detail for the first time. Observations in both visible and radio wavelengths show that this seemingly serene locale is in actuality undergoing dramatic change, with the dark clouds moving at high speeds throughout the area with the large O-type stars creating intense ultraviolet radiation creating high pressure that is contracting and destroying the denser dark clouds, each with enough material to make 15 of our suns. Hubble Heritage Picture - February 2002 February's Hubble Heritage image is of NGC 4622, a face-on spiral galaxy. 111 million light-years from us, NGC 4622 lies in the constellation Centaurus; this image covers approximately 1.6 arcminutes across (52,200 light-years). The image was originally taken on May 25, 2001, for a total exposure time of 1.7 hours. This spiral galaxy is special in that it is rotating in a direction opposite to that which astronomers thought: Clockwise. Normally, spiral arms appear to be trailing behind the directions of rotation. This is not the case in NGC 4622, where the two outside arms are actually "leading" the rotation and there is an inner arm trailing. Astronomers believe that this galaxy interacted with another, smaller galaxy. The outer arms are lopsided, indicating a disturbance. Images of the core of the galaxy offer additional clues to a merger past. The Hubble images offer new clues to understanding the peculiar properties of this galaxy. Hubble Heritage Picture - March 2002
A bow shock in space is created when two streams of gas collide. The intense solar wind from the young star featured in the center of this image is colliding with the slow-moving gas that is evaporating away from the center of the nebula (right of image). A smaller bow shock is seen in the star in the upper right of the image. These three-dimensional bow shocks have very well-defined borders facing away from the star, but the boundaries on the inside (toward the star) are much more diffuse. Scientists have found many more bow shocks around young stars in the Orion Nebula, and they are using these data to better understand the complex processes in star formation. Hubble Heritage Picture - April 2002 April's Hubble Heritage image is of NGC 2787, a galaxy with spiral arm structure. 24 million light-years from us, NGC 2787 lies in the constellation Ursa Major; this image covers approximately 38 arcseconds across (4,400 light-years). The image was originally taken on January 29, 1999, for a total exposure time of 1.2 hours. Galaxies are traditionally thought to fall into three groups: Elliptical, Spiral, and Irregular. This galaxy, however, would be classified (by the system developed by Edwin Hubble) as an SB0 - a barred lenticular galaxy. These lens-shaped galaxies have little or no spiral structure but have a bar in the center (slight, but not apparent in this image of NGC 2787). This galaxy has been used to help understand galaxy formation processes, including the roles of galaxy collisions and central black holes. In this image are also globular clusters belonging to NGC 2787. Each globular cluster are conglomerations of hundreds of thousands of stars in orbit around the galaxy. Hubble Heritage Picture - May 2002
N44C encompasses the region of ionized hydrogen gas that surrounds many hot, young stars in the Large Magellanic Cloud, a small, satellite galaxy of the Milky Way that is visible from the Southern Hemisphere. The most massive stars, 10-50 times the mass of our sun, shine at temperatures of 30,000-50,000 K (54,000-90,000 °F). The central illuminating star of N44C, however, is 75,000 K (135,000 °F). These unusually high temperatures have several proposed explanations. The most accepted is that it is a neutron star or black hole that sometimes produces x-rays, but it is now "off." N44C is part of the larger N44 complex that includes hot, young, massive stars, nebulae, and a large "bubble" that was cleared as a result of a supernova (part of this bubble is seen in red in the lower left of the image). Hubble Heritage Picture - June 2002 June's Hubble Heritage image is of IC 4406, AKA the Retina Nebula, a planetary nebula. 1,900 light-years from us, the Retina Nebula lies in the constellation Lupus; this image shows the nebula to be 0.25 light-years in the short direction and about 0.9 light-years in the long direction. The image was originally taken on June 28, 2001, and January 19, 2002, for a total exposure time of 1.3 hours. This, like most planetary nebulae, is very symmetric about the central axis. This two-dimensional image is actually of a three-dimensional torus - a shape commonly referred to as a donut. This vantage point allows a view of the filaments and structures that make up the sides of this common shape. The torus shows the confines of the central dying star's radiation. The image is made of three separate filtered images: Hydrogen is red, oxygen is blue, and nitrogen green. Radio telescopes have shown a larger zone of neutral gas, but this is not seen in visible light so is not visible in this image. One of the most interesting features of this nebula are the dark, net-like veins that run through the center of the image. These are dust lanes that are up to 160 A.U. wide and are 1000 times as dense as the rest of the nebula. They are directly at the boundary between the hot glowing gas seen in visible light and the cooler neutral gas seen in radio light. The fate of these filaments - whether or not they will survive the expansion of the nebula - remains unknown. Hubble Heritage Picture - July 2002
Cas A for short, this is the remnant from the most recent known supernova in our galaxy - 300 years ago. The former star was between 15-25 times the mass of the sun. Stars such as that have short lives - on the order of several million years - and end their existence in a massive Type II supernova. The high resolution offered by Hubble is now allowing scientists to see for the first time Cas A in detail. This image is from the upper rim of the remnant's expanding shell. In it, for the first time, can be seen a myriad of small chains, filaments, and clumps of gas and dust. Each one of these is tens of times the diameter of our solar system. The different colors shown are coded as bluer is higher oxygen concentration and redder is higher sulfur content. Hubble Heritage Picture - August 2002 August's Hubble Heritage image is of Gomez's Hamburger, a proto-planetary nebula. 6,500 light-years from us, Gomez's Hamburger lies in the constellation Sagittarius. The image was originally taken on February 22, 2002, for a total exposure time of 32 minutes. The future of our own star, this image shows the initial formation of a planetary nebula. This later phase of stellar evolution is when a star has started to expand and to slough off its outer layers. This is the vista presented in this month's Hubble Heritage picture - dust has been expelled from the central star at a wide angle and light is reflected off making the "buns." Intervening dust in a narrow band around the star block light from this portion. These effects combine to present this proto-planetary nebula that resembles a hamburger. It will further evolve into a colorful planetary nebula, such as the one in the June 2002 Hubble Heritage picture of the Retina Nebula. It is unclear how this structure formed. One theory is that this is actually a binary system, in which case one of the stars may be rapidly revolving, throwing off dust in its equatorial region much more than at higher latitudes. Gomez's Hamburger was first discovered in photographs obtained by Arturo Gomez, an astronomer at the Cerro Tololo Inter-American Observatory in Chile. Those early photographs suggested the existence of the dark band, but it was unclear due to the poorer resolution and the fuzziness that is inherent in all images taken from the ground that do not have adaptive optics. Hubble Heritage Picture - September 2002
The Hubble image represents the most detailed image of this object ever taken. It has a large, outer ring of young, hot, blue stars and an inner sphere of cooler, old, yellow stars. The seemingly empty ring area may be filled with star clusters that are too faint to see. As a side note, at the 1:00 position between the two main features resides a background object that looks remarkably similar to the foreground galaxy. There are several different ways a ring galaxy can form. One of the most common is that one galaxy smashes into or through another (such as the Cartwheel galaxy) setting off a wave of star formation. Hoag's Object shows no signs of a collision, though, so another theory is that an old galaxy was shredded into the ring shape when it passed close by. This supposed counter probably happened 2-3 billion years ago. Hoag's Object was discovered in 1950 by astronomer Art Hoag. He thought that the object looked like a planetary nebula; he quickly discounted that option and suggested that it was more likely a galaxy. Observations in the 1970's confirmed this. Hubble Heritage Picture - October 2002 October's Hubble Heritage image is of NGC 4319 and Markarian 205 (Mrk 205), a barred spiral galaxy and a quasar galaxy with companion. 80 million light-years and 1.1 billion light-years from us, respectively, these lie in the constellation Draco; this image covers approximately 1.8 arcminutes across (43,000 light-years at the distance of NGC 4319). The image was originally taken on March 10, 1997, and February 26, 2002, for a total exposure time of 1.4 hours. The barred spiral structure is clearly visible in this image. The anti-symmetric dust lanes in the interior show evidence of a recent disturbance, possibly with NGC 4291, not shown in this. In the lower left is a section of one of the outer arms of the galaxy. The much farther off quasar is pretty nearby for a quasar. Quasars, ultra-luminous galaxies thought to be powered by supermassive black holes, are found throughout the ancient universe. Usually seen as point-like objects, telescopes such as Hubble can resolve the disk of surrounding material. Mrk 205 has a smaller, compact companion galaxy, and the two are thought to be interacting. This might be responsible for the structure of the Mrk 205 halo. Optical pairings such as this are of particular interest to some astronomers, who use such pairings to argue that the quasars and galaxies really are linked, and that the methods to determine the distances (mainly redshift) give false results. Hubble Heritage Picture - November 2002
This planetary nebula is known as the Little Ghost to amateur astronomers because it appears as a faint, ghostly cloud surrounding the central dying star. This Hubble image reveals the intricate detail of the ejection process that is not visible from the ground. In its current stage of evolution, the star is emitting intense ultraviolet (UV) radiation. This has stripped gas molecules of their electrons, ionizing them (green ring). Farther out, the radiation is less intense, and the ionization process is less advanced. The gas is being ejected from the star at a rate of 24 kmps (15 miles per sec). Within 10,000 years, the gas will have dissipated into interstellar space. The color coding for this image is that doubly ionized oxygen is blue, singly ionized hydrogen is green, and singly ionized nitrogen is red. Hubble Heritage Picture - December 2002 December's Hubble Heritage image is of DEM L 106, an H II region and reflection nebula in the Large Magellanic Cloud. 160,000 light-years from us, DEM L 106 lies in the constellation Dorado; this image covers approximately 1.25 arcseconds across (59 light-years). The image was originally taken on November 14, 1998, and October 18, 2001, for a total exposure time of 1.7 hours. This image reveals complex interactions of light, gas, and dust in the satellite galaxy of the Milky Way. The small, bright gas cloud near the top of the image, N30B, was discovered in the 1950's by K. Henize, who later became a NASA astronaut. The cloud surrounds a group of hot, blue stars that have recently formed through gravitational contraction of the gas. The radiation from these stars ionizes the surrounding gas, causing it to glow by fluorescence. The bright star in the top left is called Henize S22, is a very hot and luminous supergiant star, and it is only 25 light-years from N30B. This star is rare, and it is of a blue type that is believed to be surrounded by a dense, dusty disk. The disk acts to redden the light from the star. If we were in N30B, S22 would appear to be about 250 times as bright as Venus does from Earth. The star illuminates the interstellar dust in N30B, causing a faint glow around it - a reflection nebula. The band of gas across the bottom of the image is part of the shell wall of a giant superbubble created by the stellar wind of S22. The shroud of gas surrounding N30B also shows a bow shock from the S22 wind. 
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January's
Hubble Heritage image is of Thackeray's Globules, inside of IC 2944, which
are dark clouds inside the IC 2944 star-forming region. 5,900 
March's
Hubble Heritage image is of LL Ori, a bow shock around T-Tauri 
May's
Hubble Heritage image is of N44C, a hydrogen gas (HII) region in the Large
Magellanic Cloud. 160,000 light-years from us, the Egg Nebula lies in the
constellation Dorado; this image covers approximately 2.7 arcminutes across
(126 light-years). The image was originally taken on November 13, 1996, for
a total exposure time of 1.3 hours.
July's
Hubble Heritage image is of Cassiopeia A, a 
September's
Hubble Heritage image is of Hoag's Object, a ring galaxy. 600 million light-years
from us, Hoag's Object lies in the constellation Serpens; the inner edge
of the ring has a diameter of 75,000 light-years and the outer edge a diameter
of 120,000 light-years. The image was originally taken on July 9, 2001, for
a total exposure time of 3.6 hours.
November's
Hubble Heritage image is of NGC 6369, AKA the Little Ghost Nebula, a 