LkCa 15
Star system in the constellation Taurus
From Wikipedia, the free encyclopedia
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 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 |
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]
| 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]