Epsilon Tauri b
| Exoplanet | List of exoplanets | |
|---|---|---|
 | ||
| Parent star | ||
| Star | Epsilon Tauri | |
| Constellation | Taurus | |
| Right ascension | (α) | 04h 28m 37.00s |
| Declination | (δ) | +19° 10′ 50″ |
| Apparent magnitude | (mV) | 3.53 |
| Distance | 155 ly (47.53[1] pc) | |
| Spectral type | K0III[2] | |
| Mass | (m) | 2.7 (± 0.1)[2] M☉ |
| Radius | (r) | 12.692 (± 0.545)[3] R☉ |
| Temperature | (T) | 4901 (± 20)[2] K |
| Metallicity | [Fe/H] | 0.17 (± 0.04)[2] |
| Age | 0.625 (± 0.05)[2] Gyr | |
| Physical characteristics | ||
| Mass | (m) | 7.6 (± 0.2) MJ |
| Radius | (r) | ~1.18 RJ |
| Temperature | (T) | 541 K (268 °C; 514 °F) |
| Orbital elements | ||
| Semi-major axis | (a) | 1.93 (± 0.03) AU |
| Eccentricity | (e) | 0.151 (± 0.023) |
| Orbital period | (P) | 645.5 (± 5.3) d |
| Argument of periastron |
(ω) | 94.4 ± 7.4° |
| Time of periastron | (T0) | 2,452,879 ± 12 JD |
| Semi-amplitude | (K) | 98.5 ± 1.8 m/s |
| Discovery information | ||
| Discovery date | 7 February 2007 | |
| Discoverer(s) | Sato et al. | |
| Discovery method | Doppler spectroscopy | |
| Discovery status | Confirmed | |
| Database references | ||
| Extrasolar Planets Encyclopaedia | data | |
| SIMBAD | data | |
| Exoplanet Archive | data | |
| Open Exoplanet Catalogue | data | |
Epsilon Tauri b (abbreviated ε Tauri b or ε Tau b), also named Amateru, is a super-Jupiter exoplanet orbiting the K-type giant star Epsilon Tauri approximately 155 light-years (47.53 parsecs, or nearly 1.466×1015 km) away from the Earth in the constellation of Taurus.[1] It orbits the star further out than Earth orbits the Sun. It has moderate eccentricity.[4]
The planet orbits one of the four giant stars in the Hyades cluster that is 2.7 times the mass of our Sun, making it the most massive planet-harboring star. This provides evidence that it was an A-type star when it was on the main-sequence.
In July 2014 the International Astronomical Union (IAU) launched a process for giving proper names to certain exoplanets.[5] The process involved public nomination and voting for the new names.[6] In December 2015, the IAU announced the winning name was Amateru for this planet.[7] The name was based on that submitted by the Kamagari Astronomical Observatory of Kure, Hiroshima Prefecture, Japan: namely 'Amaterasu', the Shinto goddess of the Sun, born from the left eye of the god Izanagi. The IAU substituted 'Amateru' - which is a common Japanese appellation for shrines when they enshrine Amaterasu - because 'Amaterasu' is already used for asteroid 10385 Amaterasu.[8]
Characteristics
Mass, radius and temperature
Epsilon Tauri b is a "super-Jupiter", an exoplanet that has a radius and mass larger than that of the gas giants Jupiter and Saturn. It has a temperature of 541 K (268 °C; 514 °F). It has an estimated mass of around 7.6 MJ and a potential radius of around 18% larger than Jupiter (1.18 RJ, or 12 R⊕) based on its mass, since it is more massive than the jovian planet.
Host star
The planet orbits a (K-type) giant star named Epsilon Tauri. It has exhausted the hydrogen supply in its core and is currently fusing helium. The star has a mass of 2.7 M☉ and a radius of around 12.6 R☉. It has a surface temperature of 4901 K and is 625 million years old. In comparison, the Sun is about 4.6 billion years old[9] and has a surface temperature of 5778 K.[10]
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 3.53. Therefore, Epsilon Tauri can be seen with the naked eye.
Orbit
Epsilon Tauri b orbits its star with nearly 97 times the Sun's luminosity (97 L☉) every 645 days at a distance of 1.93 AU (compared to Mars' orbital distance from the Sun, which is 1.52 AU). It has a mildly eccentric orbit, with an eccentricity of 0.15.
Discovery
Epsilon Tauri b was discovered by using the High Dispersion Echelon Spectrograph at Okayama Astrophysical Observatory (OAO) as part of a process to study G-type and K-type giant stars to search for exoplanets. Measurements of radial velocity from Epsilon Tauri were taken between December 2003 and July 2006.[4] Wobbles in the star were detected, and after analyzing the data, it was eventually concluded that there was a planetary companion with a mass 7 times that of Jupiter orbiting Epsilon Tauri every 645 days, or nearly 2 years with an eccentricity of 0.15.
See also
References
- 1 2 "Epsilon Tauri b". NASA Exoplanet Archive. Retrieved 28 July 2016.
- 1 2 3 4 5 "Notes for planet eps Tau b". The Extrasolar Planets Encyclopaedia. Retrieved 2015-09-13.
- ↑ Gerard T. van Belle and Kaspar von Braun (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars" (abstract). The Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206
. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085.(web Preprint) - 1 2 Sato, Bun'ei; et al. (2007). "A Planetary Companion to the Hyades Giant ε Tauri". The Astrophysical Journal. 661 (1): 527–531. Bibcode:2007ApJ...661..527S. doi:10.1086/513503.
- ↑ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
- ↑ NameExoWorlds The Process
- ↑ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
- ↑ NameExoWorlds The Approved Names
- ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
- ↑ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
External links
- "Notes for planet eps Tau b". The Extrasolar Planets Encyclopaedia. Retrieved 2008-06-24.
Coordinates: 
04h 28m 37.0s, +19° 10′ 50″