Kepler-91b

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
Distance3360 ly
(1030±150 pc)
Mass (m) 1.31±0.1 M☉
Radius (r) 6.3±0.16 R☉
Temperature (T) 4550±75 K
Metallicity [Fe/H] 0.11±0.07
Age 4.86±2.13 Gyr
Physical characteristics
Mass(m)0.88+0.33
−0.17 MJ
Radius(r)1.322+0.094
−0.086 RJ
Geometric Albedo(Ag)0.39 [1]
Density(ρ)0.44 g cm−3
Temperature (T) 2132 K
Orbital elements
Semi-major axis(a) 0.072+0.007
−0.002 AU
Orbital period(P) 6.24658 d
Inclination (i) 68.5+1.6
−1°
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. 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:1407.2245Freely accessible. Bibcode:2015ApJ...804..150E. doi:10.1088/0004-637X/804/2/150.
  2. 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:1312.3943Freely accessible. Bibcode:2014A&A...562A.109L. doi:10.1051/0004-6361/201322001.
  3. ↑ 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:1401.1207Freely accessible. Bibcode:2014ApJ...788..148S. doi:10.1088/0004-637X/788/2/148.
  4. ↑ 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:1511.01068Freely accessible. Bibcode:2015ApJ...814..147P. doi:10.1088/0004-637X/814/2/147.

External links

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