Astronomers have long known that the supermassive black hole at the center of the Milky Way Galaxy, known as Sagittarius A* (or Sgr A* for short), is a particularly poor eater. The fuel for this black hole comes from powerful winds blown off dozens of massive young stars that are concentrated nearby. These stars are located a relatively large distance away from Sgr A*, where the gravity of the black hole is weak, and so their high-velocity winds are difficult for the black hole to capture and swallow. Scientists have previously calculated that Sgr A* should consume only about 1% of the fuel carried in the winds.
Evidence from NASA's Chandra X-ray Observatory and the Magellan telescopes suggest a star has been torn apart by an intermediate-mass black hole in a globular cluster. In this image, X-rays from Chandra are shown in blue and are overlaid on an optical image from the Hubble Space Telescope. The Chandra observations show that this object is a so-called ultraluminous X-ray source (ULX). An unusual class of objects, ULXs emit more X-rays than any known stellar X-ray source, but less than the bright X-ray sources associated with supermassive black holes in the centers of galaxies. Their exact nature has remained a mystery, but one suggestion is that some ULXs are black holes with masses between about a hundred and a thousands times that of the Sun.
When we get to this point in the calendar, the "year in review of fill-in-the-blank" lists just come out in droves. You can't seem to drive to the mall without running over a "best of 2009" compendium of something or other. It's as if we have all had collective amnesia over the past 12 months and are required to be subjected to a crash review course of the year that was.
These two supernova remnants are part of a new study from NASA's Chandra X-ray Observatory that shows how the shape of the remnant is connected to the way the progenitor star exploded. In this study, a team of researchers examined the shapes of 17 supernova remnants in both the Milky Way galaxy and a neighbor galaxy, the Large Magellanic Cloud.
This composite image of data from three different telescopes shows an ongoing collision between two galaxies, NGC 6872 and IC 4970 (roll your mouse over the image above). X-ray data from NASA's Chandra X-ray Observatory is shown in purple, while Spitzer Space Telescope's infrared data is red and optical data from ESO's Very Large Telescope (VLT) is colored red, green and blue.
John Scott is a mission planner for Chandraâ€™s Flight Operation Team, and from time to time provides an inside look for the outside world on just how people take care of this remarkable spacecraft. This entry has a bit of a mystery in the second half of the title. If you have a guess to what it means to "Preheat at 90 for 15 minutes," then post it to the comment section. (Note to the rest of the Flight Ops Team: you're not eligible!) If someone comes up with the right answer â€“ or close to it â€“ weâ€™ll send you a Chandra poster.
As most of the nation will spend the Thanksgiving holiday devouring a stuffed turkey in the warmth of their dining room, the Chandra X-ray Observatory will give thanks for the three batteries that will keep it powered during the first day of its 22nd eclipse season. With only three and a half weeks of eclipses (eight eclipses total), this season will be brief when compared to the upcoming eclipse seasons in the following few years.
This week, the United States marks the Thanksgiving holiday. For most of us, this means lots of time with family (sometimes too much), friends, and vast amounts of food. It also causes all productivity to cease anywhere close to Thursday and the days that follow. That said, however, science and space never sleep â€“ not even from an overdose of tryptophan.
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