Top Qs
Timeline
Chat
Perspective
HD 159062
Spectroscopic binary in the constellation Hercules From Wikipedia, the free encyclopedia
Remove ads
HD 159062 is a spectroscopic binary[10] consisting of a Sun-like star and a white dwarf positioned in the northern constellation of Hercules. With an apparent magnitude of 7.305, it is too faint to be seen by the naked eye but is readily visible via binoculars.[11] It is located at a distance of 70.619 light-years (21.652 parsecs) according to parallax calculations, and is approaching the Solar System at a heliocentric radial velocity of −83.980 km/s.
Remove ads
Stellar properties
Summarize
Perspective
The primary star, designated HD 159062 A, is a G-type main-sequence star slightly cooler than the Sun with 80% the mass and 76% the radius. It has the spectral type G9V Fe−0.8, where the "Fe−0.8" suffix indicates a slight but anomalous deficiency of metals like iron.[12] Indeed, it has a low metallicity of [Fe/H]=−0.31±0.06 dex. The star is thought to be ancient, somewhere between 9-13 billion years old, and has been marked as a population II star and a candidate blue straggler.[13] It rotates on its axis at roughly 2 km/s, about the same as the Sun's equatorial rotational velocity (1.997 km/s[14]).
Based on stellar kinematics, it is very likely (88% probability) a part of the thick disk population, and has been measured to have a europium abundance typical of thick disk stars. However, it is highly enhanced in s-process elements, such as barium, lanthanum, and cerium.[15] Fuhrmann et al. (2017) noted that the barium overabundance is particularly extreme at [Ba/Fe]=0.40 dex, which they argued was almost certainly the result of stellar wind accretion from a distant (orbital period 10-1,000 years) former asymptotic giant branch primary, which would have shriveled up into a cool white dwarf companion.[16]
As predicted, a white dwarf, HD 159062 B, was discovered in 2019 by Hirsch et al.[8] in a near-circular orbit around HD 159062 A at a distance of approximately 62 AU with a period of 411 years. The low eccentricity and large separation of the orbit implies that a Roche lobe overflow never took place.[7] It was once a ~1.5 M☉ star, whose lifespan came to an end roughly 8 billion years ago and has been radiating away heat as a stellar remnant ever since.[9] It has now cooled to an effective temperature of 4,580 K (4,310 °C; 7,780 °F). Its mass, together with its orbital parameters, was determined precisely using a Python script devised in 2021.[7]
Remove ads
See also
References
Wikiwand - on
Seamless Wikipedia browsing. On steroids.
Remove ads