Aldebaran b is an exoplanet orbiting the orange giant star Aldebaran, 65 light-years away. It was initially detected in 1993, but was considered doubtful until in 2015, when researchers came to a conclusion that there is likely an exoplanet orbiting Aldebaran, consistent with the original calculations, but also compatible with stellar activity.
An artist's impression of Aldebaran b as an exoplanet.
|Discovery date||1993 (dubious)|
May 15, 2015 (confirmed)
|1.46 ± 0.27 AU (218,000,000 ± 40,000,000 km)|
|Eccentricity||0.1 ± 0.05|
|628.96 ± 0.9 d|
|1999/04/28 ± 50|
|287 ± 29|
|Temperature||1,500 K (1,230 °C; 2,240 °F)|
Mass and orbitEdit
Aldebaran b is a giant exoplanet with about 6.5 times the mass of Jupiter. It orbits at a distance about 45% farther than Earth does from the Sun. The equilibrium temperature of this planet is likely to be around 1,500 K (1,230 °C; 2,240 °F), as it is strongly irradiated by its giant host star. Nevertheless, when Aldebaran was a main sequence star, it is likely that the planet had an equilibrium temperature comparable to that of the Earth.
Aldebaran is a K-type star that is 1.16 ± 0.07 times the mass and 44 times the radius of the Sun. It has a surface temperature of 3,910 K. In comparison, the Sun has a surface temperature of 5778 K.
The exoplanet was first proposed in 1993, radial velocity measurements of Aldebaran, Arcturus and Pollux showed that Aldebaran exhibited a long-period radial velocity oscillation, which could be interpreted as a substellar companion. The measurements for Aldebaran implied a companion with a minimum mass 11.4 times that of Jupiter in a 643-day orbit at a separation of 2.0 AU (300 Gm) in a mildly eccentric orbit. However, all three stars surveyed showed similar oscillations yielding similar companion masses, and the authors concluded that the variation was likely to be intrinsic to the star rather than due to the gravitational effect of a companion.
2015 confirmed statusEdit
In 2015, a study showed stable long-term evidence for both a planetary companion and stellar activity.
- Farr, W. "Aldebaran b's temperate past uncovered in planet search data". arXiv:1802.09812. Bibcode:2018arXiv180209812F.
- Hatzes, A.P.; et al. (May 15, 2015). "Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity": 18. arXiv:1505.03454. Bibcode:2015yCat..35800031H. doi:10.1051/0004-6361/201425519.
- Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132: 161. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637.
- Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
- Hatzes, A.; Cochran, W. (1993). "Long-period radial velocity variations in three K giants". The Astrophysical Journal. 413 (1): 339–348. Bibcode:1993ApJ...413..339H. doi:10.1086/173002.
- Hatzes, A. P.; Cochran, W. D.; et al. "Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity". arXiv:1505.03454. Bibcode:2015A&A...580A..31H. doi:10.1051/0004-6361/201425519.