Using data from the Chandra X-ray Observatory, a team of astronomers studied the system formed after the supernova explosion. They were able to determine the characteristics of the dead star.
People usually think archaeology happens deep in the jungle or inside ancient pyramids. However, this is not the case. Astronomers also often act as archaeologists, trying to get important information about the past from stellar “remains”.
As an example, the binary system GRO J1655-40 is located 5500 light-years away from Earth. It consists of a black hole with nearly seven times the solar mass and a star of about half the mass.
This was not always the case. GRO J1655-40 originally consisted of two luminosities. However, the more massive of the two stars exhausted all of its nuclear fuel and exploded in a process called a supernova outburst. Its outer layers were ejected and fell on the companion star, while the inner part collapsed, crumbling in on itself, resulting in the formation of a black hole.
Over time, the distance between the black hole and the companion star has decreased due to the loss of energy by the system, mainly due to gravitational waves. This caused the black hole to start pulling matter from its neighbor, returning some of the material that was originally part of the exploded parent star.
Although most of this material fell on the black hole, a small amount of it formed a disk around it. Under the action of powerful magnetic fields and friction in the disk, its material is ejected into interstellar space in the form of powerful winds.
This is where space archaeology came into play. Astronomers used Chandra to observe GRO J1655-40 in 2005, when it was particularly bright in X-rays. The telescope detected signatures of individual elements present in the black hole’s winds, obtaining their detailed spectra.
Astronomers were subsequently able to reconstruct key physical characteristics of the exploded star from clues captured in the X-ray emission by comparing the spectra to computer models of supernovae. They found that judging by the amount of 18 different elements in the wind, the long-vanished star had a mass about 25 times that of the Sun and was much richer in elements heavier than helium compared to the Sun. This analysis paves the way for further archaeological studies of supernovae in binary star systems.
According to NASA
