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.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| 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 | |
| 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] |
| Distance | 976 ± 6 ly (299 ± 2 pc) |
| Details[4] | |
| Mass | 0.918±0.064 M☉ |
| Radius | 0.881±0.111 R☉ |
| Surface gravity (log g) | 4.50±0.10 cgs |
| Temperature | 5250±70 K |
| Metallicity [Fe/H] | 0.10±0.05 dex |
| Rotation | 20.54±0.30 d |
| Rotational velocity (v sin i) | 3.00±0.50 km/s |
| Age | ≥8[9] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Planetary system
Discovery
The two outer planets were reported as planet candidates during analysis of data from Campaign 1 of the Kepler spacecraft 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]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| d | <10 M🜨 | 0.0344(6) | 2.5081(2) | ? | 90.8(7)° | 1.11(5) R🜨 |
| b | 32.4(1.7) M🜨 | 0.0762(22) | 7.920978(19)[16] | 0.20(3) | 91.5(1)° | 7.0(2) R🜨 |
| c | 10.8(0.6) M🜨 | 0.1001(29) | 11.8993(8) | 0.21(3) | 91.1(1)° | 4.1(2) R🜨 |