NASA's Chandra Finds Unexpected Fireworks in Aftermath of Stellar Explosions
M83
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Credit: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/AURA/STScI, Hubble Heritage Team, W. Blair (STScI/Johns Hopkins University) and R. O'Connell (University of Virginia); Image Processing: NASA/CXC/SAO/A. Jubett, L. Frattare and P. Edmonds
This graphic shows two of the X-ray sources in a nearby galaxy that are changing their brightness in surprising ways as described in our latest press release. By analyzing data from NASA’s Chandra X-ray Observatory that span over 14 years, researchers found over 20 previously identified supernova remnants — remains from stars that exploded — that vary unexpectedly in X-ray brightness in Messier 83 (M83). These represent roughly half of the X-ray sources associated with supernova remnants in their sample in M83.
The panel on the left contains a composite image of M83 with X-rays from Chandra (red, green, and blue) and optical light data from NASA’s Hubble Space Telescope (red, green, and blue). The two varying Chandra sources are circled in the composite image and close-up timelapse images of these sources are shown in the panels on the right.
This collection of varying sources is surprising because astronomers expect that about a hundred years after the explosion that created them, supernova remnants do not change their brightness dramatically. Rather, they typically fade in X-rays slowly over time. It would be unusual for M83 to have so many explode less than a century ago.
The most likely explanation given by the research team is that they uncovered a population of stellar survivors — stars that lived through their partner's destruction in a supernova explosion. In this scenario, each variable X-ray source began as a pair of massive stars orbiting each other. The more massive star collapsed and exploded as a supernova, leaving behind a black hole or ultra-dense neutron star. Its companion survived.
Credit: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/AURA/STScI, Hubble Heritage Team, W. Blair (STScI/Johns Hopkins University) and R. O'Connell (University of Virginia); Image Processing: NASA/CXC/SAO/A. Jubett, L. Frattare and P. Edmonds
Chandra detects X-rays produced by infalling material that becomes superheated by the intense gravitational pull of the compact object. Such systems — known as high-mass X-ray binaries (HMXBs) — are among the most variable X-ray sources in the universe and may be the cause of the variations seen in M83’s supernova remnants. At the distance of M83, the supernova remnants appear as point sources even though they are much larger than the HMXBs they contain, implying that the two sources of X-rays cannot be separated in images.
Astronomers have known about HMXBs for decades, but the difference with this group in M83 is their connection to supernova remnants. Previously only a handful of supernova remnants associated with HMXBs were known across observations of all galaxies and so it is unprecedented to find more than twenty strong candidates in just one galaxy.
This is a composite image of the galaxy M51 combining data from NASA's Chandra X-ray Observatory (purple) with optical data (red, green and blue) taken with ground-based telescopes by a team of astrophotographers. A surprisingly high number of X-ray sources associated with supernova remnants in M51 show large changes in brightness, similar to the behavior seen in M83.
Credit: Chandra X-ray Data: NASA/CXC/SAO; Astrobin/Optical Groundbased: C.Björk, T.Bähnck, S.Donoso, J.Gentillon, A. and D.Grelin, S.Guberski, R. Hall, T.Heuberger, J.Jacks, P.Kent, Br.Meyers, W.Ostling, N.Puig, T.Schaeffer, F.Schöfbänker, M.Vasilev
There is another possible explanation for the variability seen in the Chandra sources in M83. Rather than feeding off a companion star, the black hole or neutron star may be recapturing some of the material blasted outward in the original explosion. In a possible example of cosmic recycling, debris from the explosion falls back onto the very object the supernova created. The researchers suggest that both explanations could be happening in M83 with different sources in our sample having different origins.
These results were presented at the 248th meeting of the American Astronomical Society meeting in Pasadena, CA. In addition, a paper describing these results, led by Andrea Prestwich (Catholic University, Washington, DC), has been published in The Astrophysical Journal.
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.