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K2-19

Coordinates: Sky map 11h 39m 50.4804s, +00° 36′ 12.8773″
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K2-19
Observation data
Epoch J2000      Equinox ICRS
Constellation Virgo[1]
Right ascension 11h 39m 50.4803s[2]
Declination +00° 36′ 12.875″[2]
Apparent magnitude (V) 13.002±0.009[3]
Characteristics
Evolutionary stage main sequence[2]
Spectral type K0 V[4] or G9V[5]
Apparent magnitude (J) 11.596±0.024[6]
Apparent magnitude (H) 11.208±0.022[6]
Apparent magnitude (K) 11.161±0.026[6]
Apparent magnitude (B) 13.798±0.020[3]
Variable type Planetary transit variable[7]
Astrometry
Radial velocity (Rv)−7.2296±0.0080[8] km/s
Proper motion (μ) RA: −18.673(22)‍[2] mas/yr
Dec.: 4.571(15)‍[2] mas/yr
Parallax (π)3.3410±0.0196 mas[2]
Distance976 ± 6 ly
(299 ± 2 pc)
Details[9]
Mass0.892(34) M☉
Radius0.824(24) R☉
Surface gravity (log g)4.556(24) cgs
Temperature5350(110) K
Metallicity [Fe/H]0.03(2) dex
Rotation18.36(51) d
Rotational velocity (v sin i)3.00(50)[4] km/s
Age1.70(25) Gyr
Other designations
UCAC4 454-050261, EPIC 201505350, 2MASS J11395048+0036129, Gaia DR3 3798833775141351552[10]
Database references
SIMBADdata
Exoplanet Archivedata

K2-19 is an early K-type[4] or late G-type main sequence star[5] that is magnetically active, and has a light curve that exhibits variations in brightness of ~1%.[5] It is located approximately 976 light-years away in the constellation Virgo. Three confirmed transiting exoplanets are known to orbit this star.

Planetary system

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Discovery

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The two outer planets were reported as planet candidates during analysis of data from Campaign 1 of the Kepler space telescope's K2 extended mission.[11] Both planets were confirmed by David J. Armstrong and collaborators, who used ground-based telescopes to detect additional transits and measure hour-long transit-timing variations for K2-19b.[7] They were independently validated along with 20 other planets by Benjamin T. Montet and team.[12]

K2-19d was first reported as a planet candidate during a search for candidates from the first year of the K2 Mission[13] and was later validated by Sinukoff et al.[5]

A fourth possible planet orbiting further out was reported in 2025.[9]

Characteristics

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K2-19 has a planetary system with three known planets, of which the two larger ones, K2-19b and K2-19c, are either close to the 3:2 mean motion resonance or inside it.[14][15] All three planets orbit closer to their star than the planet Mercury does to the Sun.[4][16]

The K2-19 planetary system[9]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination
(°)		 Radius
d <6.2 M🜨 0.03478(43) 2.50827+0.00027
−0.00014		 <0.44 89.7(1.6) 1.044(64) R🜨
b 30.8(1.3) M🜨 0.07487(90) 7.922806(90) 0.040(24) 89.70(26) 6.59(22) R🜨
c 11.12(44) M🜨 0.0982(12) 11.89770(46) 0.067(17) 89.37(15) 3.88(14) R🜨
e (candidate) <2.0 M🜨 0.1387(17) 19.9724(54) <0.15 89.20+0.17
−0.43		 1.22(15) R🜨

References

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  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. 1 2 3 4 5 6 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. 1 2 Henden, A. A.; et al. (2016). "VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)". VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H. 2336. Bibcode:2016yCat.2336....0H.Vizier catalog entry
  4. 1 2 3 4 Nespral, D.; et al. (2017). "Mass determination of K2-19b and K2-19c from radial velocities and transit timing variations". Astronomy and Astrophysics. 601 A128. arXiv:1604.01265. Bibcode:2017A&A...601A.128N. doi:10.1051/0004-6361/201628639. S2CID 55978628.
  5. 1 2 3 4 Sinukoff, Evan; et al. (2016). "Eleven Multiplanet Systems From K2 Campaigns 1 and 2 and the Masses of Two Hot Super-Earths". The Astrophysical Journal. 827 (1) 78. arXiv:1511.09213. Bibcode:2016ApJ...827...78S. doi:10.3847/0004-637X/827/1/78.
  6. 1 2 3 Skrutskie, Michael F.; et al. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. Vizier catalog entry
  7. 1 2 Armstrong, David J.; et al. (2015). "One of the closest exoplanet pairs to the 3:2 mean motion resonance: K2-19b and c". Astronomy and Astrophysics. 582 A33. arXiv:1503.00692. Bibcode:2015A&A...582A..33A. doi:10.1051/0004-6361/201526008. S2CID 8463154.
  8. ↑ Barros, S. C. C.; et al. (2015). "Photodynamical mass determination of the multiplanetary system K2-19". Monthly Notices of the Royal Astronomical Society. 454 (4): 4267–4276. arXiv:1510.01047. Bibcode:2015MNRAS.454.4267B. doi:10.1093/mnras/stv2271.
  9. 1 2 3 Almenara, J. M.; et al. (2025). "A decade of transit photometry for K2-19: Revised system architecture". Astronomy & Astrophysics. 703 A167. arXiv:2510.01985. Bibcode:2025A&A...703A.167A. doi:10.1051/0004-6361/202556436.
  10. ↑ "K2-19". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-12-31.
  11. ↑ Foreman-Mackey, Daniel; et al. (2015). "A Systematic Search for Transiting Planets in the K2 Data". The Astrophysical Journal. 806 (2) 215. arXiv:1502.04715. Bibcode:2015ApJ...806..215F. doi:10.1088/0004-637X/806/2/215.
  12. ↑ Montet, Benjamin T.; et al. (2015). "Stellar and Planetary Properties of K2 Campaign 1 Candidates and Validation of 17 Planets, Including a Planet Receiving Earth-like Insolation". The Astrophysical Journal. 809 (1) 25. arXiv:1503.07866. Bibcode:2015ApJ...809...25M. doi:10.1088/0004-637X/809/1/25.
  13. ↑ Vanderburg, Andrew; et al. (2016). "Planetary Candidates from the First Year of the K2 Mission". The Astrophysical Journal Supplement Series. 222 (1) 14. arXiv:1511.07820. Bibcode:2016ApJS..222...14V. doi:10.3847/0067-0049/222/1/14.
  14. ↑ Petigura, Erik A.; et al. (January 2020). "K2-19b and c are in a 3:2 Commensurability but out of Resonance: A Challenge to Planet Assembly by Convergent Migration". The Astronomical Journal. 159 (1) 2. arXiv:1910.12899. Bibcode:2020AJ....159....2P. doi:10.3847/1538-3881/ab5220.
  15. ↑ Petit, Antoine C; Petigura, Erik A; Davies, Melvyn B; Johansen, Anders (2020-08-11). "Resonance in the K2-19 system is at odds with its high reported eccentricities". Monthly Notices of the Royal Astronomical Society. 496 (3): 3101–3111. arXiv:2003.04931. Bibcode:2020MNRAS.496.3101P. doi:10.1093/mnras/staa1736.
  16. ↑ Williams, David R. (2018-09-27). "Mercury Fact Sheet". NASA. Retrieved 2019-01-12.
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