Space Spider turned out to be a powerful source of gamma rays

(ORDO NEWS) — Using the 4.1-meter SOAR telescope in Chile, astronomers have discovered the first known case of a binary system where a star in the process of becoming a white dwarf orbits a neutron star that has just completed its transformation into a rapidly spinning pulsar.

This pair, discovered initially with the help of the Fermi space gamma-ray observatory (“Fermi”), is the “missing link” in the evolution of such binary systems.

The bright, mysterious gamma-ray source turned out to be a rapidly spinning neutron star – called a millisecond pulsar – that orbits the star as it evolves into an extremely low-mass white dwarf. Astronomers call such binary systems “spiders”, because the pulsar “eats” the outer parts of the companion star, while the latter gradually turns into a white dwarf.

In their work, astronomers studied a source called 4FGL J1120.0-2204, previously discovered using the Fermi observatory, which has so far remained unidentified. This source, however, was the second brightest gamma-ray source in the sky among all unidentified sources.

In their work, the researchers were able to identify the source 4FGL J1120.0-2204 and showed that it is a binary system consisting of a millisecond pulsar, which is the precursor of an extremely low mass white dwarf. The pair is located at a distance of about 2600 light years from us.

The lines of the optical spectra of the future white dwarf, which is part of the 4FGL J1120.0-2204 system, showed a Doppler shift, indicating a revolution around the pulsar with a period of 15 hours.

“These spectra also allowed us to estimate the mass of the companion star,” said study lead author Samuel Swihart of the US Naval Research Laboratory. – This star will eventually form a white dwarf of extremely low mass, no more than 17 percent of the mass of the Sun. Temperatures on the surface of this white dwarf reach about 8200 degrees Celsius.”


Contact us:

Our Standards, Terms of Use: Standard Terms And Conditions.