Kepler-91b
Exoplanet | List of exoplanets | |
---|---|---|
Parent star | ||
Star | Kepler-91 | |
Constellation | Lyra | |
Right ascension | (α) | 19h 02m 41.0s |
Declination | (δ) | +44° 07′ 00″ |
Apparent magnitude | (mV) | 12.9 |
Distance | 3360 ly (±150 1030 pc) | |
Mass | (m) | ±0.1 1.31 M☉ |
Radius | (r) | ±0.16 6.3 R☉ |
Temperature | (T) | ±75 4550 K |
Metallicity | [Fe/H] | ±0.07 0.11 |
Age | ±2.13 4.86 Gyr | |
Physical characteristics | ||
Mass | (m) | +0.33 −0.17 0.88MJ |
Radius | (r) | +0.094 −0.086 1.322RJ |
Geometric Albedo | (Ag) | 0.39 [1] |
Density | (ρ) | 0.44 g cm−3 |
Temperature | (T) | K 2132 |
Orbital elements | ||
Semi-major axis | (a) | +0.007 −0.002 0.072AU |
Orbital period | (P) | 58 6.246d |
Inclination | (i) | +1.6 −1° 68.5 |
Discovery information | ||
Discovery date | 2013 | |
Discoverer(s) | ||
Discovery method | Transit (Kepler Mission) | |
Other detection methods | Ellipsoidal light variations Reflection/emission modulations | |
Discovery status | Confirmed | |
Other designations | ||
KOI 2133.01
|
Kepler-91b is a planet orbiting Kepler-91, a star slightly more massive than the Sun. Kepler-91 has left the main sequence and is now a red giant branch star.
Discovery and further confirmation
Kepler-91b was detected by analyzing the data of Kepler spacecraft where a transit-like signal was found. Initially thought to be a false positive due to light curve variations by a self-luminous object, it was later revealed that due to low density of Kepler-91's shape is distorted to slightly ellipsoidal shape due to gravitational effects of the planet. Ellipsoidal light variations caused by Kepler-91b constitute more than the third of light variations compared to transit depth. Ellipsoidal light variations also allowed to determine the planet's mass. It was also found that Kepler-91b reflects some of the starlight from its star.[2]
Further analysis managed to question the planetary nature of the object, suspecting that it is a self-luminous object. However, the planetary nature was eventually confirmed again.[3]
Characteristics
Kepler-91b is about 14% less massive than Jupiter while being more than 35% larger, making it less than half of the density of water. Kepler-91b orbits around the host star in about 6.25 days. Despite being one of the least edge-on orbits relative to Earth with inclination being about 68.5 degrees, transit was detected due to low semi-major axis to host star radius ratio.
Kepler-91b is expected to be engulfed by the parent star within about 55 million years.[2][1]
Possible trojan companion
The possibility of a trojan planet to Kepler-91b was studied but the conclusion was that the transit-signal was a false-positive.[4]
References
- 1 2 Esteves, Lisa J.; De Mooij, Ernst J. W.; Jayawardhana, Ray (2014). "Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry". The Astrophysical Journal. 804 (2): 150. arXiv:1407.2245. Bibcode:2015ApJ...804..150E. doi:10.1088/0004-637X/804/2/150.
- 1 2 Lillo-Box, J.; Barrado, D.; Moya, A.; Montesinos, B.; Montalbán, J.; Bayo, A.; Barbieri, M.; Régulo, C.; Mancini, L.; Bouy, H.; Henning, T. (2013). "Kepler-91b: A planet at the end of its life. Planet and giant host star properties via light-curve variations". Astronomy & Astrophysics. 562: A109. arXiv:1312.3943. Bibcode:2014A&A...562A.109L. doi:10.1051/0004-6361/201322001.
- ↑ Sliski, David H.; Kipping, David M. (2014). "A High False Positive Rate for Kepler Planetary Candidates of Giant Stars using Asterodensity Profiling". The Astrophysical Journal. 788 (2): 148. arXiv:1401.1207. Bibcode:2014ApJ...788..148S. doi:10.1088/0004-637X/788/2/148.
- ↑ Placek, Ben; Knuth, Kevin H.; Angerhausen, Daniel; Jenkins, Jon M. (2015). "Characterization of Kepler-91b and the Investigation of a Potential Trojan Companion Using EXONEST". The Astrophysical Journal. 814 (2): 147. arXiv:1511.01068. Bibcode:2015ApJ...814..147P. doi:10.1088/0004-637X/814/2/147.