K2-19

K2-19 is a 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] Three confirmed transiting exoplanets are known to orbit this star.

K2-19
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo[1]
Right ascension  11h 39m 50.4804s[2]
Declination +00° 36′ 12.8773″[2]
Apparent magnitude (V) 13.002±0.009[3]
Characteristics
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: −18.788±0.104[2] mas/yr
Dec.: 4.415±0.066[2] mas/yr
Parallax (π)3.4230 ± 0.0658[2] mas
Distance950 ± 20 ly
(292 ± 6 pc)
Details[4]
Mass0.918±0.064 M☉
Radius0.881±0.111 R☉
Surface gravity (log g)4.50±0.10 cgs
Temperature5250±70 K
Metallicity [Fe/H]0.10±0.05 dex
Rotation20.54±0.30 d
Rotational velocity (v sin i)3.00±0.50 km/s
Age≥8[9] Gyr
Other designations
Gaia DR2 3798833775141351552, UCAC4 454-050261, EPIC 201505350[10]
Database references
SIMBADdata

Planetary system

Discovery

The two outer planets were reported as planet candidates during analysis of data from Campaign 1 of the Kepler spacecrafts 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]

Characteristics

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

The K2-19 planetary system[4][8][5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 54.4±8.9 M⊕ 0.0762±0.0022 7.91951+0.00040
−0.00012		 0.023+0.240
−0.020		 88.87+0.16
−0.60°		 7.16±0.91 R⊕
c 7.5+3.0
−1.4 M⊕		 0.1001±0.0029 11.9066+0.0021
−0.0014		 0.183+0.283
−0.003		 88.92+0.14
−0.41°		 4.34±0.55 R⊕
d ? M⊕ 0.0344±0.0006 2.50856±0.00041 ? 85.83+2.97
−4.74°		 1.14±0.13 R⊕
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References
  1. Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
  2. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. 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. 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.
  5. 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. Skrutskie, M. F.; et al. (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. 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.
  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. Narita, Norio; et al. (2015). "Characterization of the K2-19 Multiple-transiting Planetary System via High-dispersion Spectroscopy, AO Imaging, and Transit Timing Variations". The Astrophysical Journal. 815 (1). 47. arXiv:1510.01060. Bibcode:2015ApJ...815...47N. doi:10.1088/0004-637X/815/1/47.
  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. Williams, David R. (2018-09-27). "Mercury Fact Sheet". NASA. Retrieved 2019-01-12.

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