LkCa 15

LkCa 15 is a T Tauri star in the Taurus Molecular Cloud. These types of stars are relatively young pre-main-sequence stars that show irregular variations in brightness.^[7] It has a mass that is about 97% of the Sun,^[2] an effective temperature of 4370 K,^[5] and is slightly cooler than the Sun. Its apparent magnitude is 11.91,^[2] meaning it is not visible to the naked eye.

LkCa 15

LkCa 15 protoplanetary disk
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Taurus
Right ascension	04h 39m 17.796s[1]
Declination	+22° 21′ 03.48″[1]
Apparent magnitude (V)	+11.91[2]
Characteristics
Spectral type	K5V[2]
Variable type	T Tauri[1]
Astrometry
Proper motion (μ)	RA: 10.572[3] mas/yr Dec.: -17.527[3] mas/yr
Parallax (π)	6.3619±0.0264 mas[3]
Distance	513 ± 2 ly (157.2 ± 0.7 pc)
Details
Mass	0.97 ± 0.03[2] M☉
Radius	1.2[4] R☉
Luminosity	1.22[5] L☉
Temperature	4730[4] K
Age	2[2] Myr
Other designations
V1079 Tau, GSC 01278-00193, TYC 1278-193-1, 2MASS J04391779+2221034[1]
Database references
SIMBAD	data

A light curve for V1079 Tauri, adapted from Alencar et al. (2018)^[6]

Planetary system

LkCa 15 is surrounded by a protoplanetary disk, typical of many T Tauri stars.^[7] The disk around the star is about 55 times more massive than Jupiter,^[8] and consists of three major belts (components).^[4] Small changes in the observed brightness of the disk may be due to a planetary companion; the star was believed to have a protoplanetary object or exoplanet orbiting it, known as LkCa 15 b^[9][10] This name stems from an older survey.^[11] Later, the existence of up to three planets was suspected. The planets' existence was refuted in 2019 as higher resolution imaging became available.^[4]

The LkCa 15 planetary system

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
Protoplanetary disk component 1	0.12–3[4] AU				50[4]°	—
b (unconfirmed)	6±1 MJ	15.7±2.1	40000	—	—	—
Protoplanetary disk component 2	20–40[4] AU				51.5[4]°	—
Protoplanetary disk component 3	55–160[4] AU				50[4]°	—

LkCa 15 b is a candidate protoplanetary object in orbit around LkCa 15, a star in the Taurus-Auriga Star Forming Region. Its potential discovery was effected by direct imaging techniques using the Keck II telescope in 2011 by Adam Kraus and Michael Ireland.^[9] A 2015 study of observations from the Magellan Telescopes and the Large Binocular Telescope argued that the planet is forming through accretion.^[10] It would be the first observed exoplanet seen in the process of active accretion.^[12] The planet’s existence was refuted in 2019 as higher resolution imaging became available.^[4]