Atlas (star)


Image of the Pleiades star cluster
Red circle.svg
Atlas in the Pleiades cluster (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 03h 49m 09.74258s[1]
Declination +24° 03′ 12.3003″[1]
Apparent magnitude (V) 3.63[2] (3.84 / 5.46)[3]
Spectral type B8III[4]
U−B color index -0.36[5]
B−V color index -0.08[5]
Variable type Suspected
Radial velocity (Rv)8.5 ± 2[6] km/s
Proper motion (μ) RA: 17.70[1] mas/yr
Dec.: -44.18[1] mas/yr
Parallax (π)8.53 ± 0.39[1] mas
Distance431 ± 13 ly
(132 ± 4[7] pc)
Period (P)290.984 ± 0.079 d
Semi-major axis (a)13.08 ± 0.12 mas
Eccentricity (e)0.2385 ± 0.0063
Inclination (i)107.87 ± 0.49°
Longitude of the node (Ω)154.0 ± 0.7°
Periastron epoch (T)JD 2450583.0 ± 1.9
Argument of periastron (ω)
151.9 ± 2.2°
Semi-amplitude (K1)
26.55 ± 1.41 km/s
Semi-amplitude (K2)
36.89 ± 0.22 km/s
Atlas A
Mass4.74 ± 0.25[7] M
Radius2.0[8] R
Surface gravity (log g)3.483 ± 0.113[4] cgs
Temperature13446 ± 218[4] K
Rotational velocity (v sin i)280[4] km/s
Atlas B
Mass3.42 ± 0.25[7] M
Other designations
27 Tau, BD+23° 557, FK5 142, HD 23850, HIP 17847, HR 1178, SAO 76228
Database references

Atlas /ˈætləs/,[9] designation 27 Tauri, is a triple star system[not verified in body] in the constellation of Taurus. It is a member of the Pleiades, an open star cluster (M45). It is 431 light-years (132 parsecs) away,[7] and is 3.92 degrees north of the ecliptic.


27 Tauri is the star's Flamsteed designation.

In 2016 the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalogue and standardize proper names for stars. The WGSN approved the name Atlas for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.[11]


Atlas was a Titan and the father of the Pleiades sisters in Greek mythology.


The primary component, Atlas A, is a blue-white B-type giant with an apparent magnitude of +3.62.[2] It is a binary star whose components have magnitudes of 3.84 and 5.46.[3] The binary makes one orbit every 290 days, and the eccentricity is about 0.24.[7]


  1. ^ a b c d e van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ a b Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. ^ a b "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 21 June 2017.
  4. ^ a b c d David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. S2CID 33401607.
  5. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
  7. ^ a b c d e f Zwahlen, N.; North, P.; Debernardi, Y.; Eyer, L.; Galland, F.; Groenewegen, M. A. T.; Hummel, C. A. (2004). "A purely geometric distance to the binary star Atlas, a member of the Pleiades". Astronomy & Astrophysics. 425 (3): L45. arXiv:astro-ph/0408430. Bibcode:2004A&A...425L..45Z. doi:10.1051/0004-6361:200400062. S2CID 37047575.
  8. ^ Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy & Astrophysics. 367 (2): 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754.
  9. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  10. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  11. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.

External links

  • Alcyone ephemeris