October 25, 2011 4:13
American astronomers using several space telescopes have unraveled the mystery of the earliest on record of a supernova that exploded about 2 thousand years ago, according to NASA.
In 185, the Chinese astronomers discovered a star in the sky, the guest, which suddenly appeared and remained visible for about eight months. In the 1960s, scientists have determined that the star was the first supernova, an outbreak of which survived documented. In its place was found nebula, designated RCW 86. It lies about 8000 light-years from Earth in the constellation Circinus.
The study of the nebula, or as it is called by astronomers remnant raised new questions: This spherical gas bubble was much larger than expected. If we could see in the infrared light, the size, the sky would have been larger than the full moon, it was about 85 light-years in diameter. In addition, it expands faster than it was supposed to.
"This supernova remnant was really big and very rapidly expanding. It is two to three times more than we could have expected after nablyudavvsheysya supernova explosion that occurred about two thousand years ago, "- said Brian Williams of the University of North Carolina, the lead author of the study published in the Astrophysical Journal.
"We are now able to determine the cause of this," — he said.
Helped unravel observations using infrared space telescope "Spitzer" and WISE, as well as through data collected X-ray telescope "Chandra" and "Newton» (XMM-Newton). Astronomers have determined that the ancient Chinese supernova of type Ia.
Such supernovae are formed in binary star systems, one of which is a white dwarf — a hot ultra-dense dwarf star that remains after burning hydrogen in a star similar to our Sun. Midgets overtighten over matter with the companion star, its mass increases, at their core run fusion reactions leading to the explosion of a supernova.
"White Dwarf — is a smoking ash from the extinct fire. If you splash it with gasoline, an explosion, "- said Williams.
In addition, the observations show that even before the explosion of a white dwarf has created around him a huge cavity where there was almost no interstellar gas and dust. This "pre-clearance" allowed nebula created after the flash, so fast and so far to expand.
Observations with the "Spitzer" and WISE allowed the authors of the study to measure the temperature of the dust around the former supernova, which was equal to about 200 degrees below zero. The researchers then calculated how much gas must be present in the nebula, dust to warm up to this temperature, and came to the conclusion that most of the time after the supernova nebula around was the environment of very low density, that is was "dovzryvnaya" cavity.
Until now, scientists believed that RCW 86 is the product of the second type of supernova explosion occurring in the collapse of a massive star. The cavity can be pressurized substance, which threw a massive star before it exploded. However, the data from the X-ray telescopes, "Chandra" and "Newton" show that tummanost contains a lot of iron, so it is a product of a supernova explosion of type Ia.