K2-19#Planetary system
{{Short description|Orangish-hued star in the constellation Virgo}}
{{Starbox begin}}
{{Starbox observe
| epoch = J2000
| constell = Virgo
| appmag_v = {{val|13.002|0.009}}
}}
{{Starbox character
| appmag_1_passband = J
| appmag_1 = {{val|11.596|0.024}}
| appmag_2_passband = H
| appmag_2 = {{val|11.208|0.022}}
| appmag_3_passband = K
| appmag_3 = {{val|11.161|0.026}}
| appmag_4_passband = B
| appmag_4 = {{val|13.798|0.020}}
| b-v =
| u-b =
| variable = Planetary transit variable
}}
{{Starbox astrometry
| radial_v = {{val|−7.2296|0.0080}}
| prop_mo_ra = {{val|−18.673|(22)}}
| prop_mo_dec = {{val|4.571|(15)}}
| parallax = 3.3410
| p_error = 0.0196
| absmag_v =
}}
{{Starbox detail
| mass = {{val|0.918|0.064}}
| radius = {{val|0.881|0.111}}
| luminosity =
| gravity = {{val|4.50|0.10}}
| temperature = {{val|5250|70}}
| metal_fe = {{val|0.10|0.05}}
| rotation = {{val|20.54|0.30|u=days}}
| rotational_velocity = {{val|3.00|0.50}}
}}
{{Starbox catalog
| names = {{odlist | name=UCAC4 454-050261 | 2MASS=J11395048+0036129 | EPIC=201505350 | Gaia DR3=3798833775141351552 }}
}}
{{Starbox reference
| Simbad = K2-19
}}
{{Starbox end}}
K2-19 is an early K-type or late G-type main sequence star that is magnetically active, and has a light curve that exhibits variations in brightness of ~1%. It is located approximately 976 light-years away in the constellation Virgo. Three confirmed transiting exoplanets are known to orbit this star.
Planetary system
=Discovery=
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. 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. They were independently validated along with 20 other planets by Benjamin T. Montet and team.
K2-19d was first reported as a planet candidate during a search for candidates from the first year of the K2 Mission and was later validated by Sinukoff et al.
=Characteristics=
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. All three planets orbit closer to their star than the planet Mercury does to the Sun.
{{OrbitboxPlanet begin
}}
{{OrbitboxPlanet
| exoplanet = d
| mass_earth = <10
| semimajor = {{val|0.0344|(6)}}
| period = {{val|2.5081|(2)}}
| eccentricity = ?
| inclination = {{val|90.8|(7)}}
| radius_earth = {{val|1.11|(5)}}
}}
{{OrbitboxPlanet
| exoplanet = b
| mass_earth = {{val|32.4|(1.7)}}
| semimajor = {{val|0.0762|(22)}}
| period = {{val|7.920978|(19)}}
| eccentricity = {{val|0.20|(3)}}
| inclination = {{val|91.5|(1)}}
| radius_earth = {{val|7.0|(2)}}
}}
{{OrbitboxPlanet
| exoplanet = c
| mass_earth = {{val|10.8|(0.6)}}
| semimajor = {{val|0.1001|(29)}}
| period = {{val|11.8993|(8)}}
| eccentricity = {{val|0.21|(3)}}
| inclination = {{val|91.1|(1)}}
| radius_earth = {{val|4.1|(2)}}
}}
{{Orbitbox end}}
References
{{reflist|refs=
{{Cite Gaia EDR3|3798833775141351552}}
{{cite simbad | title=K2-19 | access-date=2018-12-31 }}
}}
{{Stars of Virgo}}
{{exoplanets}}
{{Sky|11|39|50.4804|+|00|36|12.8773}}
{{DEFAULTSORT:K2-19}}
Category:K-type main-sequence stars
Category:Planetary systems with three confirmed planets