21 Tauri

21 Tauri
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 03h 45m 54.47676s[1]
Declination +24° 33′ 16.2418″[1]
Apparent magnitude (V) 5.76[2]
Characteristics
Evolutionary stage main sequence[2]
Spectral type B8 V[3]
B−V color index +0.04[2]
Astrometry
Radial velocity (Rv)+6.0±0.6[4] km/s
Proper motion (μ) RA: +20.025[5] mas/yr
Dec.: −45.949[5] mas/yr
Parallax (π)7.5658 ± 0.1321 mas[1]
Distance431 ± 8 ly
(132 ± 2 pc)
Absolute magnitude (MV)+0.34[6]
Details
Mass2.93±0.07[2] M☉
Luminosity100+15
−13[2] L☉
Surface gravity (log g)4.250±0.113[7] cgs
Temperature11,041±76[2] K
Rotational velocity (v sin i)159[8] km/s
Age100[9] Myr
Other designations
Asterope, Sterope I[10], 21 Tau, BD+24° 553, GC 4502, HD 23432, HIP 17579, HR 1151, SAO 76159[11]
Database references
SIMBADdata

21 Tauri, formally known as Asterope /əˈstrɛrəpiː/,[12][13] is a component of the Asterope double star in the Pleiades open cluster. 21 Tauri is the stars' Flamsteed designation. This star is potentially faintly visible to the naked eye with an apparent visual magnitude of 5.76 in ideal conditions,[2] although anybody viewing the object is likely to instead see the pair as a single elongated form of magnitude 5.6.[14] The distance to 21 Tauri can be estimated from its annual parallax shift of 7.6 mas,[1] yielding a range of around 431 light years. It is moving further from the Earth with a heliocentric radial velocity of +6 km/s.[4]

Asterope was one of the Pleiades sisters in Greek mythology. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[16] It approved the name Asterope for 21 Tauri on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[13]

21 Tauri is a blue-white hued B-type main sequence star with a stellar classification of B8 V.[3] It is a single[17] star with around three[2] times the mass of the Sun and is 100[9] million years old. The star is radiating 100[2] times the Sun's luminosity from its photosphere at an effective temperature of 11,041 K.[2] It displays an infrared excess, but this is due to reflection nebula rather than a circumstellar disk.[9]

  1. ^ a b c d Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f g h i j Cite error: The named reference zorec2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Palmer1968 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference GaiaDR1 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference David2015 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Simón-Díaz2017 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Smith2010 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Allen1899 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Davis, George A. (1944). "The pronunciations, derivations, and meanings of a selected list of star names". Popular Astronomy. 52: 8–30. Bibcode:1944PA.....52....8D.
  13. ^ a b Cite error: The named reference IAU-LSN was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Schaaf2012 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference WGSN was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference TriRpt18 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference chini2012 was invoked but never defined (see the help page).