The Absolute Cosmos: New eclipsing binary system discovered in Kepler data

An international team of scientists discovered a new eclipsing binary system named EPIC 216747137. The binary system seems to be PCEB (post-common-envelope binary) of HW Virginis class.

The system was discovered using data from Kepler Space Telescope’s extended mission called K2. Kepler is a retired space telescope launched by NASA in 2009. After nine years of service telescope was retired in 2018.

Eclipsing binary systems show regular light variations because one of the star passes directly in front of the other star in the system.

Among post-common-envelope binary, HW Virginis stars are type of eclipsing binaries which consist a hot subdwarf primary star with an M-dwarf star as companion.

Lately, scientists have discovered large number of HW Virginis systems from the light curves of the OGLE and ATLAS projects. Studying these binaries will expand our understanding about stellar evolution.

Scientists expect to discover more HW Virginis system using NASA’s TESS (Transiting Exoplanet Survey Satellite).

Scientists detected EPIC 216747137 in Kepler’s K2 mission data. The discovery was confirmed by further follow up observations from SAAO (South African Astronomical Observatory), the La Silla Observatory and the NOT (Nordic Optical Telescope).

EPIC 216747137 system is located about 2,900 light years away from us. It consists a hot sub luminous star of sdOB spectral class as primary star and a cool low mass M-dwarf star as secondary companion.

The system has an orbital period of only about 3.87 hours which produces a strong reflection effect from the secondary companion star.

The radius of primary star is about 0.21 solar radii and it is approx. thirty eight percent less massive than Sun. Star has an effective temperature of about 40,127 degrees Celsius and its rotational velocity is fifty one kilometre per second.

Whereas, the secondary star has a radius of nearly 0.14 solar radii and has a mass of about 0.11 solar masses. The star has an effective temperature of about 2,727 degrees Celsius. M-dwarf is separated from the primary star by about 1.21 solar radii.

According to scientists EPIC 216747137 is located just five hundred and five light years below the Galactic plane, which suggests that system is in Milky Way’s thin disk.

Source: a new HW Vir eclipsing binary with a massive sdOB primary and a low-mass M-dwarf companion.

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