BD-07 436, also known as WASP-77 since 2012,[7] is a binary
star system about 344 light-years away. The star's components appears to have a different age, with the secondary older than 9 billion years, while the primary's age is 5 billion years.[2] The BD-07 436 system's concentration of heavy elements is similar to the Sun. Its stars display moderate chromospheric activity, including
x-rayflares.[2]
The primary is a
G-type main-sequence star, BD-07 436A (WASP-77A). The star is rotating rapidly, being spun up by the tides raised by the giant planet
WASP-77Ab on its close orbit.[6] The secondary is a
K-type main-sequence star BD-07 436B orbiting at a distance of 461+200 −140AU.[4]
Planetary system
In 2012 a
transitinghot Jupiter planet
b was detected on a very tight, circular orbit.[7] The planet may have an extended gaseous envelope and is losing mass.[2] Its equilibrium temperature is 1715+26 −25K,[5]the nightside temperature measured in 2019 is 1786±84
K,[8] and dayside planetary temperature measured in 2020 is 1842+34 −33K.[9]
Water vapour was detected on the planetary dayside of
WASP-77Ab, indicating C/O ratio similar to solar or even lower.[10]
^
abcdefgMaxted, P. F. L.; Anderson, D. R.; Collier Cameron, A.; Doyle, A. P.; Fumel, A.; Gillon, M.; Hellier, C.; Jehin, E.; Lendl, M.; Pepe, F.; Pollacco, D. L.; Queloz, D.; Ségransan, D.; Smalley, B.; Southworth, K.; Smith, A. M. S.; Triaud, A. H. M. J.; Udry, S.; West, R. G. (2012), "WASP-77 Ab: A transiting hot Jupiter planet in a wide binary system", Publications of the Astronomical Society of the Pacific, 125 (923): 48–55,
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