Astronomy:Kepler-1638

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Kepler-1638 is a G-type subgiant star located about 5,000 light years away in the constellation of Cygnus.[1] One known exoplanet has been found orbiting the star: Kepler-1638b.[2][3][4][5]As of January 2021, Kepler-1638 is the farthest star with a known exoplanet orbiting in the habitable zone.[6]

Planetary system

The Kepler-1638 planetary system[7]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b ~4.16 M⊕ 0.745+0.021
−0.020
259.33683±0.01303 — 89.9954+0.0021
−0.0844
°
1.87+0.33
−0.22
 R⊕

Kepler-1638 b is an exoplanet in orbit of its star, Kepler-1638, located in the constellation Cygnus. It was confirmed in 2016 as part of a study statistically validating hundreds of Kepler planets. Based on the parameters in the discovery paper, the planet is a super-Earth, with a radius of 1.87+0.33
−0.22
 R🜨
, and a predicted mass of 4.16 Earths. It has an orbit of 259.337±0.013 days in its system's habitable zone and orbits 0.745 AU from its star. It is the most distant known exoplanet that is considered potentially habitable.[7][5][2][3][4]

However, these parameters were estimated before the first measurement of the host star's parallax was published as part of Gaia DR2 in 2018. The Gaia parallax suggests a distance of about 1,548 parsecs (5,050 light-years),[8] much farther than the pre-Gaia estimate of about 764 parsecs (2,490 light-years).[9] This revised distance results in a significantly larger estimate of the radius of the star, and thus of the planet, with a 2018 study finding a planetary radius of 3.226+0.201
−0.315
 R🜨
. This would make the planet an ice giant like Neptune, and thus not potentially habitable in an Earth-like sense.[10][7]

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific 99 (617): 695. doi:10.1086/132034. Bibcode: 1987PASP...99..695R  Constellation record for this object at VizieR.
  2. ↑ 2.0 2.1 Burgess, Matt (2016-05-11). "Nasa's Kepler telescope just found 1,284 exoplanets" (in en-GB). Wired UK. ISSN 1357-0978. https://www.wired.co.uk/article/kepler-planets-new-exoplanets. Retrieved 2021-01-22. 
  3. ↑ 3.0 3.1 "Exoplanet-catalog". https://exoplanets.nasa.gov/exoplanet-catalog/2284/kepler-1638-b/. 
  4. ↑ 4.0 4.1 Mike Wall (11 May 2016). "1st Alien Earth Still Elusive Despite Huge Exoplanet Haul" (in en). https://www.space.com/32852-alien-earth-search-nasa-kepler-space-telescope.html. 
  5. ↑ 5.0 5.1 Morton, Timothy D.; Bryson, Stephen T.; Coughlin, Jeffrey L.; Rowe, Jason F.; Ravichandran, Ganesh et al. (May 2016). "False Positive Probabilities for all Kepler Objects of Interest: 1284 Newly Validated Planets and 428 Likely False Positives". The Astrophysical Journal 822 (2): 86. doi:10.3847/0004-637X/822/2/86. Bibcode: 2016ApJ...822...86M. 
  6. ↑ "The Habitable Exoplanets Catalog - Planetary Habitability Laboratory @ UPR Arecibo". http://phl.upr.edu/projects/habitable-exoplanets-catalog. 
  7. ↑ 7.0 7.1 7.2 "Kepler-1638". https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-1638. 
  8. ↑ Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  9. ↑ Torres, Guillermo (December 2017). "Validation of Small Kepler Transiting Planet Candidates in or near the Habitable Zone". The Astronomical Journal 154 (6): 264. doi:10.3847/1538-3881/aa984b. Bibcode: 2017AJ....154..264T. 
  10. ↑ Berger, Travis A.; Huber, Daniel; Gaidos, Eric; van Saders, Jennifer L. (October 2018). "Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2". The Astrophysical Journal 866 (2): 99. doi:10.3847/1538-4357/aada83. Bibcode: 2018ApJ...866...99B. 

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See also