From AAS NOVA: “A Giant Planet Around an Evolved Binary”



17 December 2019
Susanna Kohler

Illustration of the planetary system KIC 10544976, in which a giant planet orbits a binary white dwarf and M dwarf. [Leandro Almeida]

In a study led by Leonardo Almeida (Federal University of Rio Grande do Norte and University of São Paulo, Brazil), scientists announce evidence for a 13-Jupiter-mass planet around an evolved binary system, KIC 10544976, that consists of a white dwarf and a red dwarf star orbiting each other once every 0.35 days.

Why it’s interesting:

This is the first planet found orbiting an evolved binary like this one, and it raises questions as to how it formed. Was the planet born at the same time as the stars, and somehow survived the end of life of the binary member that evolved into a white dwarf? Or was the planet instead born later, out of the gas ejected by this star as it died? By studying the KIC 10544976 planet with next generation telescopes, we should be able to answer this question.

How the planet was discovered:

Observations of the eclipsing binary stars show timing variations in the eclipses. This change in orbit could be caused by one of two things: either the gravitational tug of an additional unseen, massive body, or period fluctuations in the magnetic field of the red dwarf. By studying the magnetic activity cycle for the red dwarf using years of flare and starspot data, Almeida and collaborators were able to rule out the hypothesis that magnetic activity caused the eclipse timing variations. This made the presence of a giant planet the most likely explanation.

Telescopes involved with this project

Isaac Newton Group of Telescopes located at Roque de los Muchachos Observatory on La Palma in the Canary Islands Altitude 2,396 m (7,861 ft)

ING 4.2 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands, 2,396 m (7,861 ft)


L. A. Almeida et al 2019 AJ 157 150.

See the full article here .


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