Astronomers have discovered the first example of a binary system by using the 4.1-meter SOAR Telescope in Chile. Here a star in the process of becoming a white dwarf is orbiting a neutron star. This star has just finished turning into a rapidly spinning pulsar. This is detected by Fermi Gamma-ray Space Telescope. This is a “missing link” in the evolution of such binary systems.
Scientists found a bright, mysterious source of gamma rays. It was rapidly spinning neutron star. It was orbiting a star in the process of evolving into an extremely-low-mass white dwarf. Scientists call these types of binary systems as “spiders”. As the pulsar “eat” the outer parts of the companion star as it turns into a white dwarf.
Astronomers have used the 4.1-meter SOAR Telescope on Cerro Pachón in Chile. This is a part of Cerro Tololo Inter-American Observatory (CTIO).
NASA’s Fermi Gamma-ray Space Telescope has catalogued objects in the universe which produce copious gamma rays. But it could not classify all the sources of gamma rays. One source is named as 4FGL J1120.0-2204 by astronomers. It is the second brightest gamma-ray source in the entire sky that had gone unidentified.
Astronomers from the United States and Canada have used the Goodman Spectrograph on the SOAR Telescope to identify 4FGL J1120.0-2204. The gamma-ray source emits X-rays. This was observed by NASA’s Swift and ESA’s XMM-Newton space telescopes. It was a binary system consisting of a “millisecond pulsar”. This spins hundreds of times per second. The pressure to an extremely-low-mass white dwarf. It is located over 2600 light-years away.
Goodman spectrograph measured optical spectrum of the binary system. It has showed the light from the proto-white dwarf companion is Doppler shifted. This indicates that it orbits a compact neutron star every 15 hours. When a star reaches the end of its life, it run out of the hydrogen used to fuel the nuclear fusion processes inside it.
Then helium takes over and powers the star. This causes heat up and it prompts its expansion and evolution into a red giant. The outer layers of this swollen star then accreted onto a binary companion and nuclear fusion halts. This leaves behind white dwarf about the size of Earth, temperature exceeding 100,000 °C.