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 |
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.
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]
References
- ^ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- ^ a b c d "EM* LkCa 15". SIMBAD. Centre de données astronomiques de Strasbourg.
- ^ a b c d e f "Notes on LKCA 15 b". Extrasolar Planets Encyclopaedia. 1995. Retrieved 26 December 2016.
- ^ a b c Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d e f g h i j k Currie, Thayne; et al. (2019), "No Clear, Direct Evidence for Multiple Protoplanets Orbiting Lk Ca 15: Lk Ca 15 BCD are Likely Inner Disk Signals", The Astrophysical Journal, 877 (1): L3, arXiv:1905.04322, Bibcode:2019ApJ...877L...3C, doi:10.3847/2041-8213/ab1b42, S2CID 152282903
- ^ a b Thalmann, C.; Mulders, G. D.; Hodapp, K.; Janson, M.; Grady, C. A.; Min, M.; De Juan Ovelar, M.; Carson, J.; Brandt, T.; Bonnefoy, M.; McElwain, M. W.; Leisenring, J.; Dominik, C.; Henning, T.; Tamura, M. (2014). "The architecture of the Lk Ca 15 transitional disk revealed by high-contrast imaging". Astronomy & Astrophysics. 566: A51. arXiv:1402.1766. Bibcode:2014A&A...566A..51T. doi:10.1051/0004-6361/201322915. S2CID 34485844.
- ^ Alencar, S. H. P.; Bouvier, J.; Donati, J.-F.; Alecian, E.; Folsom, C. P.; Grankin, K.; Hussain, G. A. J.; Hill, C.; Cody, A.-M.; Carmona, A.; Dougados, C.; Gregory, S. G.; Herczeg, G.; Ménard, F.; Moutou, C.; Malo, L.; Takami, M.; collaboration, MaTYSSE (December 2018). "Inner disk structure of the classical T Tauri star LkCa 15". Astronomy and Astrophysics. 620: A195. arXiv:1811.04806. Bibcode:2018A&A...620A.195A. doi:10.1051/0004-6361/201834263.
- ^ a b "Encyclopedia of Science: T Tauri star". Archived from the original on 27 January 2021. Retrieved 17 January 2017.
- ^ Bouvier, J.; Cabrit, S.; Fernandez, M.; Martin, E. L.; Matthews, J. M. (May 1993). "COYOTES I : the photometric variability and rotational evolution of T Tauri stars". Astronomy and Astrophysics. 272: 176–206. Bibcode:1993A&A...272..176B. Retrieved 1 September 2025.
- ^ Kazarovets, E. V.; Samus, N. N. (January 1995). "The 72nd Name-List of Variable Stars". Information Bulletin on Variable Stars. 4140: 1–28. Bibcode:1995IBVS.4140....1K. Retrieved 1 September 2025.
- ^ Andrews, Sean M.; Williams, Jonathan P. (2005). "Circumstellar Dust Disks in Taurus-Auriga: The Submillimeter Perspective". The Astrophysical Journal. 631 (2): 1134–1160. arXiv:astro-ph/0506187. Bibcode:2005ApJ...631.1134A. doi:10.1086/432712. S2CID 17583379.
- ^ a b Kraus, Adam L.; Ireland, Michael J. (2012). "LkCa 15: A Young Exoplanet Caught at Formation?". The Astrophysical Journal. 745 (1): 5. arXiv:1110.3808. Bibcode:2012ApJ...745....5K. doi:10.1088/0004-637x/745/1/5. S2CID 73598684.
- ^ a b Sallum, S.; Follette, K. B.; Eisner, J. A.; Close, L. M.; Hinz, P.; Kratter, K.; Males, J.; Skemer, A.; MacIntosh, B.; Tuthill, P.; Bailey, V.; Defrère, D.; Morzinski, K.; Rodigas, T.; Spalding, E.; Vaz, A.; Weinberger, A. J. (2015). "Accreting protoplanets in the Lk Ca 15 transition disk". Nature. 527 (7578): 342–4. arXiv:1511.07456. Bibcode:2015Natur.527..342S. doi:10.1038/nature15761. PMID 26581290. S2CID 916170.
- ^ Herbig, G. H.; Vrba, F. J.; Rydgren, A. E. (1986). "A spectroscopic survey of the Taurus-Auriga dark clouds for pre-main-sequence stars having CA II H, K emission". The Astronomical Journal. 91: 575. Bibcode:1986AJ.....91..575H. doi:10.1086/114039.
- ^ Irene Klotz (18 November 2015). "Astronomers see planet still growing in its stellar womb". News Daily. Reuters. Archived from the original on 19 November 2015. Retrieved 20 November 2015.