Kepler-80

Kepler-80

Observation data Epoch J2000       Equinox J2000
Constellation	Cygnus [1]
Right ascension	19h 44m 27.0201s [2]
Declination	+39° 58′ 43.594″ [2]
Apparent magnitude  (V)	14.804[ citation needed ]
Characteristics
Evolutionary stage	main sequence [2]
Spectral type	M0V [3]
Variable type	planetary transit
Astrometry
Proper motion (μ)	RA: −1.373(20) mas/yr [2] Dec.: −7.207(24) mas/yr [2]
Parallax (π)	2.6675±0.0183  mas [2]
Distance	1,223 ± 8  ly (375 ± 3  pc)
Details
Mass	0.730[ citation needed ]  M☉
Radius	0.678[ citation needed ]  R☉
Luminosity	0.170[ citation needed ]  L☉
Temperature	4540[ citation needed ]  K
Metallicity [Fe/H]	−0.56 [4]   dex
Rotation	25.567±0.252 days [5]
Other designations
KOI-500, KIC 4852528, 2MASS J19442701+3958436 [3]
Database references
SIMBAD	data
KIC	data

Kepler-80, also known as KOI-500, is a red dwarf star of the spectral type M0V. ^[3] This stellar classification places Kepler-80 among the very common, cool, class M stars that are still within their main evolutionary stage, known as the main sequence. Kepler-80, like other red dwarf stars, is smaller than the Sun, and it has both radius, mass, temperatures, and luminosity lower than that of our own star. ^[6] Kepler-80 is found approximately 1,223 light years from the Solar System, in the stellar constellation Cygnus, also known as the Swan.

The Kepler-80 system has 6 known exoplanets. ^{[7] [8]} The discovery of the five inner planets was announced in October 2012, marking Kepler-80 as the first star identified with five orbiting planets. ^{[9] [6]} In 2017, an additional planet, Kepler-80g, was discovered by use of artificial intelligence and deep learning to analyse data from the Kepler space telescope. ^[8] The method used to discover Kepler-80g had been developed by Google, and during the same study another planet was found, Kepler-90i, which brought the total number of known planets in Kepler-90 up to 8 planets. ^[10]

Planetary system

The exoplanets around Kepler-80 were discovered and observed using the Kepler Space Telescope. This telescope uses the so called transit method , where the planets move in between the star and the Earth and thereby dim the light of the star as seen from the Earth. By using photometry the transit of a planet in front of its star can be seen as a dip in the light curve of the star. After the initial discovery the five innermost planets have all been confirmed through additional investigations. Kepler-80b and Kepler-80c were both confirmed in 2013 based on their transit-timing variation (TTV). ^[11] Kepler-80d and Kepler-80e were validated in 2014 based on statistical analysis of the Kepler data. ^{[12] [13]} Finally the innermost planet, Kepler-80f was confirmed in 2016. ^[13]

All six known planets in the Kepler-80 system orbit very close to the star, and their distances to the star (the semi-major axes are all smaller than 0.2 AU). For comparison the planet in the Solar System closest to the star, Mercury, has a semi major axis of 0.389 AU, and so the entire known system of Kepler-80 can lie within the orbit of Mercury. ^[14] This makes Kepler-80 a very compact system and it is one of many STIP's (Systems with Tightly-packed Inner Planets) that have been discovered by the Kepler telescope. ^[9]

In 2014, the dynamical simulation shown what the Kepler-80 planetary system have likely to undergone a substantial inward migration in the past, producing an observed pattern of lower-mass planets on tightest orbits. ^[15]

The Kepler-80 planetary system ^{[4] [8] [16] [17] [18]}

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
f	—	0.0175 ± 0.0002	0.98678730 ± 0.00000006	~0	86.50 +2.36 −2.59 °	1.031+0.033 −0.027 [19]   R🜨
d	4.1 ± 0.4 [20]   M🜨	0.0372 ± 0.0005 [19]	3.07221 ± 0.00003	0.005+0.004 −0.003 [20]	88.35 +1.12 −1.51 [19] °	1.309+0.036 −0.032 [19]   R🜨
e	2.2 ± 0.4 [20]   M🜨	0.0491 ± 0.0007 [19]	4.6453 +0.00010 −0.00009 [20]	0.008 ± 0.004 [20]	88.79 +0.84 −1.07 [19] °	1.330+0.039 −0.038 [19]   R🜨
b	2.4 ± 0.6 [20]   M🜨	0.0658 ± 0.0009 [19]	7.05325 ± 0.00009 [20]	0.006 +0.005 −0.004 [20]	89.34 +0.46 −0.62 [19] °	2.367+0.055 −0.052 [19]   R🜨
c	3.4+0.9 −0.7 [20]   M🜨	0.0792 ± 0.0011 [19]	9.5232 ± 0.0002 [20]	0.010 +0.006 −0.005 [20]	89.33 +0.47 −0.57 [19] °	2.507+0.061 −0.058 [19]   R🜨
g	1.0 ± 0.3 [20]   M🜨	0.142 +0.037 −0.051 [19]	14.6471 +0.0007 −0.0012 [20]	0.02 +0.03 −0.02 [20]	89.35 +0.47 −0.98 [19] °	1.05+0.22 −0.24 [19]   R🜨

Orbital resonance

The system Kepler-80 has orbits locked in a trio of three-body mean-motion orbital resonances; between Kepler-80 d, e, and b; between Kepler-80 e, b, and c; and between Kepler-80 b, c, and g. Interestingly, no two-body resonances have been found to exist in this system. ^[20]

While Kepler-80 d, e, b, c and g's periods are in a ~ 1.000: 1.512: 2.296: 3.100: 4.767 ratio, in a frame of reference that rotates with the conjunctions this reduces to a ratio of 4:6:9:12:18. Conjunctions of d and e, e and b, b and c, and c and g occur at relative intervals of 2:3:6:6 in a pattern that repeats about every 191 days. Modeling indicates the resonant system is stable to perturbations. Triple conjunctions do not occur. ^{[8] [16]}

References

1. Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific . 99 (617): 695. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Constellation record for this object at VizieR.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
3. "Kepler-80". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2023-03-01.
4. "OASIS". Abstractsonline.com. Retrieved 2012-11-22.
5. McQuillan, A.; Mazeh, T.; Aigrain, S. (2013). "Stellar Rotation Periods of The Kepler objects of Interest: A Dearth of Close-In Planets Around Fast Rotators". The Astrophysical Journal Letters. 775 (1). L11. arXiv: 1308.1845 . Bibcode:2013ApJ...775L..11M. doi:10.1088/2041-8205/775/1/L11. S2CID   118557681.
6. MacDonald, Mariah G.; Ragozzine, Darin; Fabrycky, Daniel C.; Ford, Eric B.; Holman, Matthew J.; Isaacson, Howard T.; Lissauer, Jack J.; Lopez, Eric D.; Mazeh, Tsevi (October 2016). "A Dynamical Analysis of the Kepler-80 System of Five Transiting Planets". The Astronomical Journal. 152 (4): 105. arXiv: 1607.07540 . Bibcode:2016AJ....152..105M. doi: 10.3847/0004-6256/152/4/105 . ISSN   1538-3881. S2CID   119265122.
7. Xie, J.-W. (2013). "Transit timing variation of near-resonance planetary pairs: confirmation of 12 multiple-planet systems". Astrophysical Journal Supplement Series. 208 (2): 22. arXiv: 1208.3312 . Bibcode:2013ApJS..208...22X. doi:10.1088/0067-0049/208/2/22. S2CID   17160267.
8. Shallue, C. J.; Vanderburg, A. (2017). "Identifying Exoplanets With Deep Learning: A Five Planet Resonant Chain Around Kepler-80 And An Eighth Planet Around Kepler-90" (PDF). The Astrophysical Journal . 155 (2): 94. arXiv: 1712.05044 . Bibcode:2018AJ....155...94S. doi: 10.3847/1538-3881/aa9e09 . S2CID   4535051 . Retrieved 2017-12-15.
9. Ragozzine, Darin; Kepler Team (2012-10-01). "The Very Compact Five Exoplanet System KOI-500: Mass Constraints from TTVs, Resonances, and Implications". AAS/Division for Planetary Sciences Meeting Abstracts #44. 44: 200.04. Bibcode:2012DPS....4420004R.
10. St. Fleur, Nicholas (14 December 2017). "An 8th Planet Is Found Orbiting a Distant Star, With A.I.'s Help". The New York Times . Retrieved 15 December 2017.
11. Xie, Ji-Wei; Wu, Yanqin; Lithwick, Yoram (2014-06-25). "Frequency of Close Companions Amongkeplerplanets—A Transit Time Variation Study". The Astrophysical Journal. 789 (2): 165. arXiv: 1308.3751 . Bibcode:2014ApJ...789..165X. doi:10.1088/0004-637x/789/2/165. ISSN   0004-637X. S2CID   7024042.
12. Lissauer, Jack J.; Marcy, Geoffrey W.; Bryson, Stephen T.; Rowe, Jason F.; Jontof-Hutter, Daniel; Agol, Eric; Borucki, William J.; Carter, Joshua A.; Ford, Eric B. (2014-03-04). "Validation Ofkepler's Multiple Planet Candidates. Ii. Refined Statistical Framework and Descriptions of Systems of Special Interest". The Astrophysical Journal. 784 (1): 44. arXiv: 1402.6352 . Bibcode:2014ApJ...784...44L. doi:10.1088/0004-637x/784/1/44. ISSN   0004-637X. S2CID   119108651.
13. Rowe, Jason F.; Bryson, Stephen T.; Marcy, Geoffrey W.; Lissauer, Jack J.; Jontof-Hutter, Daniel; Mullally, Fergal; Gilliland, Ronald L.; Issacson, Howard; Ford, Eric (2014-03-04). "Validation Ofkepler's Multiple Planet Candidates. III. Light Curve Analysis and Announcement of Hundreds of New Multi-Planet Systems". The Astrophysical Journal. 784 (1): 45. arXiv: 1402.6534 . Bibcode:2014ApJ...784...45R. doi:10.1088/0004-637x/784/1/45. ISSN   0004-637X. S2CID   119118620.
14. "Mercury Fact Sheet". nssdc.gsfc.nasa.gov. Retrieved 2019-04-14.
15. T. O. Hands, R. D. Alexander, W. Dehnen, "Understanding the assembly of Kepler's compact planetary systems", 2014
16. MacDonald, Mariah G.; Ragozzine, Darin; Fabrycky, Daniel C.; Ford, Eric B.; Holman, Matthew J.; Isaacson, Howard T.; Lissauer, Jack J.; Lopez, Eric D.; Mazeh, Tsevi (2016-01-01). "A Dynamical Analysis of the Kepler-80 System of Five Transiting Planets". The Astronomical Journal. 152 (4): 105. arXiv: 1607.07540 . Bibcode:2016AJ....152..105M. doi: 10.3847/0004-6256/152/4/105 . S2CID   119265122.
17. "Kepler-80 g". NASA Exoplanet Archive. Retrieved 14 December 2017.
18. "Kepler-80". NASA Exoplanet Archive. Retrieved May 9, 2018.
19. MacDonald, Mariah G.; Shakespeare, Cody J.; Ragozzine, Darin (2021), "A Five-Planet Resonant Chain: Reevaluation of the Kepler-80 System", The Astronomical Journal, 162 (3): 114, arXiv: 2107.05597 , Bibcode:2021AJ....162..114M, doi: 10.3847/1538-3881/ac12d5 , S2CID   235795313
20. Weisserman, Drew; Becker, Juliette; Vanderburg, Andrew (2023), "Kepler-80 Revisited: Assessing the Participation of a Newly Discovered Planet in the Resonant Chain", The Astronomical Journal, 165 (3): 89, arXiv: 2212.08695 , Bibcode:2023AJ....165...89W, doi: 10.3847/1538-3881/acac80