Epsilon Tucanae

Epsilon Tucanae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Tucana
Right ascension 23h 59m 54.97761s[1]
Declination −65° 34′ 37.6804″[1]
Apparent magnitude (V) +4.50[2]
Characteristics
Spectral type B8 V[3] or B9 IV[4]
U−B color index −0.28[2]
B−V color index −0.08[2]
Astrometry
Radial velocity (Rv)+8.8±2.8[5] km/s
Proper motion (μ) RA: +47.93[1] mas/yr
Dec.: −22.95[1] mas/yr
Parallax (π)8.74 ± 0.18 mas[1]
Distance373 ± 8 ly
(114 ± 2 pc)
Absolute magnitude (MV)−0.80[6]
Details
Mass4.00±0.20[3] M☉
Luminosity389[3] L☉
Surface gravity (log g)3.9±0.1[3] cgs
Temperature13,000±500[3] K
Rotation0.79318(8)[7] d
Rotational velocity (v sin i)300±20[3] km/s
Age123[3] Myr
Other designations
ε Tuc, CPD−66° 3819, FK5 903, HD 224686, HIP 118322, HR 9076, SAO 255619[8]
Database references
SIMBADdata

Epsilon Tucanae (ε Tuc, ε Tucanae) is a solitary[9] star in the southern constellation of Tucana. With an apparent visual magnitude of +4.50,[2] it is faintly visible to the naked eye. Based upon an annual parallax shift of 8.74 mas as seen from Earth, it is located around 373 light years from the Sun.

Levenhagen and Leister (2008) classified this star as B8 V,[3] indicating a blue-white hued B-type main sequence star. However, Hiltner, Garrison, and Schild (1969) listed it with a classification of B9 IV,[4] suggesting it may be a more evolved subgiant star. It is a rapidly rotating Be star that is an estimated 78% of the way through its main sequence lifetime.[10] The projected rotational velocity is 300 km/s,[3] which is giving it an oblate shape with an equatorial bulge that is an estimated 36% larger than the polar radius.[11] It has a weak magnetic field with a strength of 74±24 G.[12]

It is the last star in the Hipparcos catalogue, HIP 118322, from the Hipparcos (1989–1993) astrometry satellite.

  1. ^ a b c d e Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  3. ^ a b c d e f g h i Cite error: The named reference Levenhagen2006 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Hiltner1969 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Gontcharov2006 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 Barraza was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Zorec2005 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference belle2012 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Hubrig2009 was invoked but never defined (see the help page).