More than fifty years ago, a supernova was discovered in M83, a spiral galaxy about 15 million light years from Earth. Astronomers have used NASA's Chandra X-ray Observatory to make the first detection of X-rays emitted by the debris from this explosion.
Named SN 1957D because it was the fourth supernova to be discovered in the year 1957, it is one of only a few located outside of the Milky Way galaxy that is detectable, in both radio and optical wavelengths, decades after its explosion was observed. In 1981, astronomers saw the remnant of the exploded star in radio waves, and then in 1987 they detected the remnant at optical wavelengths, years after the light from the explosion itself became undetectable.
A relatively short observation -- about 14 hours long -- from NASA's Chandra X-ray Observatory in 2000 and 2001 did not detect any X-rays from the remnant of SN 1957D. However, a much longer observation obtained in 2010 and 2011, totaling nearly 8 and 1/2 days of Chandra time, did reveal the presence of X-ray emission. The X-ray brightness in 2000 and 2001 was about the same as or lower than in this deep image.
This new Chandra image of M83 is one of the deepest X-ray observations ever made of a spiral galaxy beyond our own. This full-field view of the spiral galaxy shows the low, medium, and high-energy X-rays observed by Chandra in red, green, and blue respectively.
The new X-ray data from the remnant of SN 1957D provide important information about the nature of this explosion that astronomers think happened when a massive star ran out of fuel and collapsed. The distribution of X-rays with energy suggests that SN 1957D contains a neutron star, a rapidly spinning, dense star formed when the core of pre-supernova star collapsed. This neutron star, or pulsar, may be producing a cocoon of charged particles moving at close to the speed of light known as a pulsar wind nebula.
If this interpretation is confirmed, the pulsar in SN 1957D is observed at an age of 55 years, one of the youngest pulsars ever seen. The remnant of SN 1979C in the galaxy M100 contains another candidate for the youngest pulsar, but astronomers are still unsure whether there is a black hole or a pulsar at the center of SN 1979C.
Image Credits: X-ray: NASA/CXC/STScI/K.Long et al., Optical: NASA/STScI
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| Chandra X-ray Observatory |
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Wikipedia: Chandra-teleskopet, Chandra X-ray Observatory, uppskjutet 1999 av NASA, är ett rymdteleskop som letar efter röntgenstrålning. Teleskopet är uppkallat efter Subrahmanyan Chandrasekhar. Det har främst använts till att undersöka energirika fenomen som exempelvis svarta hål och kolliderande galaxer.
Uppskjutningen skedde med rymdfärjan Columbia, den 23 juli 1999 under uppdragsnamnet STS-93.
Wikipedia: Messier 83, Södra Vindsnurregalaxen, M83 eller NGC 5236 är en spiralgalax belägen på omkring 15 miljoner ljusårs avstånd i stjärnbilden Hydran.
Messier 83 är en av de närmaste stavspiralerna på stjärnhimlen, ligger ungefär 13 grader sydost om Messier 68. Messier 83 har en magnitud på 8 och är lätt att se med små teleskop och kikare. I ett 150 mm teleskop syns den som en suddig elliptisk ljusfläck med ett litet mycket ljust centrum.
Man har observerat totalt sex supernovor (SN 1923A, SN 1945B, SN 1950B, SN 1957D, SN 1968LL och SN 1983N) i Messier 83.
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