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.^[8] It has a mass that is about 97% of the Sun,^[3] an effective temperature of 4370 K,^[6] and is slightly cooler than the Sun. Its apparent magnitude is 11.91,^[3] 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[1]
Right ascension	04h 39m 17.796s[2]
Declination	+22° 21′ 03.48″[2]
Apparent magnitude (V)	+11.91[3]
Characteristics
Spectral type	K5V[3]
Variable type	T Tauri[2]
Astrometry
Proper motion (μ)	RA: 10.572[4] mas/yr Dec.: -17.527[4] mas/yr
Parallax (π)	6.3619±0.0264 mas[4]
Distance	513 ± 2 ly (157.2 ± 0.7 pc)
Details
Mass	0.97 ± 0.03[3] M☉
Radius	1.2[5] R☉
Luminosity	1.22[6] L☉
Temperature	4730[5] K
Age	2[3] Myr
Other designations
V1079 Tau, GSC 01278-00193, TYC 1278-193-1, 2MASS J04391779+2221034[2]
Database references
SIMBAD	data

A light curve for V1079 Tauri, adapted from Alencar et al. (2018)^[7]

In 1993, Jérôme Bouvier et al. announced that LkCa 15 is a variable star.^[9] It was given its variable star designation, V1079 Tauri, in 1995.^[10]

Planetary system

LkCa 15 is surrounded by a protoplanetary disk, typical of many T Tauri stars.^[8] The disk around the star is about 55 times more massive than Jupiter,^[11] and consists of three major belts (components).^[5] 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^[12][13] This name stems from an older survey.^[14] Later, the existence of up to three planets was suspected. The planets' existence was refuted in 2019 as higher resolution imaging became available.^[5]

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[5] AU				50[5]°	—
b (unconfirmed)	6±1 MJ	15.7±2.1	40000	—	—	—
Protoplanetary disk component 2	20–40[5] AU				51.5[5]°	—
Protoplanetary disk component 3	55–160[5] AU				50[5]°	—

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.^[12] A 2015 study of observations from the Magellan Telescopes and the Large Binocular Telescope argued that the planet is forming through accretion.^[13] It would be the first observed exoplanet seen in the process of active accretion.^[15] The planet’s existence was refuted in 2019 as higher resolution imaging became available.^[5]