Parceiros NASA Grupo de Astrofísica do MSFC SAO (Observatório Smithsoniano de Astrofísica) - Câmera MIT (Instituto Tecnológico de Massachusets) - CCD/Redes Universidade do Estado de Pennsylvania - CCD Universidade de Leicester (Inglaterra) - Câmera SRON (Oganização Pesquisas Espaciais da Holanda) - Redes Instituto Max Planck (Alemanha) - Redes
Lançamento 23 de Julho de 1999 Cabo Canaveral (Flórida) Ônibus Epacial Columbia
This false-color image shows the central region of our Milky Way Galaxy as seen by Chandra. The bright, point-like source at the center of the image was produced by a huge X-ray flare that occurred in the vicinity of the supermassive black hole at the center of our galaxy. This central black hole has about 2.6 million times the mass of our sun and is associated with the compact radio source Sagittarius A*. During the observation the X-ray source at the galactic center brightened dramatically in a few minutes, and after about 3 hours, rapidly declined to the pre-flare level. The rapid variation in X-ray intensity indicates that the flare was due to material as close to the black hole as the Earth is to the sun. This is the most compelling evidence yet that matter falling toward the black hole is fueling energetic activity in the galactic center.
Left image: The X-ray data from the Chandra X-ray Observatory have revealed a bright central star surrounded by a cloud of multimillion-degree gas in the planetary nebula known as the Cat's Eye. This Chandra image, where the intensity of the X-ray emission is correlated to the brightness of the orange coloring, captures the expulsion of material from a star that is expected to collapse into a white dwarf in a few million years. The intensity of X rays from the central star was unexpected, and it is the first time astronomers have seen such X-ray emission from the central star of a planetary nebula. The ACIS X-ray camera aboard Chandra observed NGC 6543 on May 10-11, 1999, for a total exposure time of 46,000 seconds.
Right image: This composite image of Chandra and Hubble Space Telescope data offers astronomers an opportunity to compare where the hotter, X-ray emitting gas appears in relation to the cooler material seen in optical wavelengths. The Chandra team found that the chemical abundances in the region of hot gas (its X-ray intensity is shown in purple) were like those in the wind from the central star and different from the outer cooler material (the red and green structures.) Although still incredibly energetic and hot enough to radiate X rays, Chandra shows the hot gas to be somewhat cooler than scientists would have expected for such a system. These results present a puzzle since the temperature of the X-ray emitting material suggests that mixing might have occurred. This discrepancy means some other process has created the "lukewarm" X-ray emission observed by Chandra. The color composite of optical and X-ray images was made by Zoltan G. Levay (Space Telescope Science Institute). The optical images were taken by J.P. Harrington and K.J. Borkowski (University of Maryland) with the Hubble Space Telescope
Credit Left: X-ray (NASA/UIUC/Y.Chu et al.), Right: X-ray/Optical Composite (X-ray: NASA/UIUC/Y.Chu et al., Optical: NASA/HST) Scale Images are 30 arcsec on a side Category Planetary Nebula Coordinates (J2000) RA 17h 58m 33.30s | Dec +66'' 37' 59.20'' Constellation DracoDraco Observation Date (of primary image used) May 10-11, 2000 Observation Time (of primary image used) 12.8 hours Obs. ID (of primary image used) 630 Color Code Intensity Instrument ACIS
The Chandra image of the twin quasars Q2345+007 A, B shows that they are not identical twins. This means that it is unlikely that they are an optical illusion, rather, they were probably created by merging galaxies. When galaxies collide, the flow of gas onto the central supermassive black holes of each of the galaxies can be enhanced, resulting in two quasars. The light from the quasar pair started its journey toward Earth 11 billion years ago. Galaxies were about three times closer together then than they are now, so collisions were much more likely. Quasar pairs that are seen close to one another on the sky and are at the same distance from Earth often turn out to be an illusion as part of a gravitationally lensed system. In these cases, the image of a single quasar has been split into two or more images as its light has been bent and focused on its way to Earth by the gravity of an intervening massive object like a galaxy, or a cluster of galaxies.
The quasar pair Q2345+007 A, B was thought to be such an illusion because of the remarkably similar patterns of the light, or spectra, from the pair at both optical and ultraviolet wavelengths. However no intervening galaxy or cluster has been found for this pair, leading to the speculation that the gravitational light-bending might be caused by a new type of cluster that contains hot gas and dark matter, but no stars. Such a dark cluster would be invisible to optical and ultraviolet telescopes, but would be detectable in X-rays. The Chandra X-ray images showed no evidence for a massive dark cluster. Further, the X-ray spectra of the two quasars were distinctly different, supporting the idea that they are distinct objects, rather than a mirage.
Credit NASA/SAO/CXC/P.Green et al. Scale Image is 30 arcsec per side. Category Quasar Constellation PiscesPisces Observation Date May 26, 2000 and June 27, 2000 Observation Time 18 hours total Color Code colors indicate X-ray energy bands - red (low), green (medium), and blue (high) Instrument ACIS Distance Estimate 11 billion light years
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