LkCa 15

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LkCa 15
LkCa 15 disk protoplanetare Scheibe cropped.jpg
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) V1079TauLightCurve.png
A light curve for V1079 Tauri, adapted from Alencar et al. (2018)

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]

The LkCa 15 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
Protoplanetary disk component 10.12–3 [5] AU 50 [5] ° —
b(unconfirmed)6±1 MJ 15.7±2.140000———
Protoplanetary disk component 220–40 [5] AU 51.5 [5] ° —
Protoplanetary disk component 355–160 [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

  1. ↑ 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.
  2. 1 2 3 4 "EM* LkCa 15". SIMBAD . Centre de données astronomiques de Strasbourg.
  3. 1 2 3 4 5 6 "Notes on LKCA 15 b". Extrasolar Planets Encyclopaedia . 1995. Retrieved 26 December 2016.
  4. 1 2 3 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.
  5. 1 2 3 4 5 6 7 8 9 10 11 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
  6. 1 2 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.
  7. ↑ 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 .
  8. 1 2 "Encyclopedia of Science: T Tauri star". Archived from the original on 27 January 2021. Retrieved 17 January 2017.
  9. ↑ 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.
  10. ↑ 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.
  11. ↑ 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.
  12. 1 2 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.
  13. 1 2 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.
  14. ↑ 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 .
  15. ↑ 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.
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