119 Tauri

119 Tauri

The sky position of 119 Tauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 05h 32m 12.75251s[1]
Declination +18° 35′ 39.2436″[1]
Apparent magnitude (V) 4.23 - 4.54[2]
Characteristics
Spectral type M2Iab-Ib[2]
U−B color index +2.23[3]
B−V color index +2.08[3]
Variable type SRc[2]
Astrometry
Radial velocity (Rv)+23.75[4] km/s
Proper motion (μ) RA: 1.86[1] mas/yr
Dec.: −4.48[1] mas/yr
Parallax (π)1.82 ± 0.26[1] mas
Distanceapprox. 1,800 ly
(approx. 550 pc)
Absolute magnitude (MV)−5.20[5]
Details
Mass14.37+2.00
−2.77[6] M☉
Radius587 - 593[6] R☉
Luminosity66,000[6] L☉
Surface gravity (log g)+0.05+0.11
−0.17[6] cgs
Temperature3,801 - 3,820[6] K
Metallicity0.0[7]
Age13.9+1.0
−2.5[6] Myr
Other designations
CE Tauri, HR 1845, HD 36389, BD+18°875, HIP 25945, SAO 94628, GC 6841, AAVSO 0526+18
Database references
SIMBADdata

119 Tauri (also known as CE Tauri) is a red supergiant star in the constellation Taurus. It is a semiregular variable and its angular diameter has been measured at about 10″.

Description

119 Tauri has a spectral class of M2 and a luminosity class of Iab-Ib, intermediate between an intermediate-luminosity supergiant and a less luminous supergiant. It is approximately 1,800 light years from Earth. The star is classified as a semiregular variable star and its brightness varies from magnitude +4.23 to +4.54 with a period of 165 days.[2] With a colour index of +2.07, it is one of the reddest naked eye stars in the night sky.[3]

Occultations

CE Tauri lies 4.6 degrees off the ecliptic. This makes it a candidate for occultations by the Moon and (extremely rarely) by one of the bright planets. The star's angular diameter has been measured by lunar occultation, giving limb-darkened visible light angular diameters of 9.1±0.8 mas,[8] 10.9±1.0 mas,[9] and 9.0±0.2 mas.[10] An occultation has also been observed in H-alpha, giving a diameter of 17±1 mas, which indicates that there is circumstellar hydrogen producing emission across at least that size, nearly twice the visible diameter.[10]

Angular diameter

The angular diameter has also been measured directly by VLBI, leading to limb-darkened diameters of 10.68±0.21 mas,[11] 9.83±0.07 mas,[12] 9.3±0.5 mas,[13] 9.97±0.08 mas,[7], 10.24±0.05 mas,[6] 9.68±0.05 mas.[6] Although CE Tauri is classified as a pulsating variable, observations using the same equipment and wavelengths have not detected significant changes in the angular diameter over time.[7] Reconstructed images of the surface show bright spots that are attributed to giant convection cells.[6]

Angular diameter measurements can be combined with absolute observed fluxes to derive an accurate effective temperature, in this case about 3,800 K. Combined with a distance, the linear size of the star can be calculated. CE Tauri is found to have a radius of around 590 R☉. Then the bolometric luminosity is the star is found to be about 66,000 L☉. Comparison with stellar evolutionary tracks shows CE Tauri to have evolved from an initial mass of 15 M☉ and to have a current mass of 14.37 M☉.[6] An alternative interpretation of observations, under the assumption that CE Tauri is an asymptotic giant branch (AGB) star, give it a current mass of 8 M☉ and a luminosity of 44,000 L☉.[7]

References

  1. 1 2 3 4 5 Van Leeuwen, F. (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.
  2. 1 2 3 4 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published In: 2009yCat....102025S. 1: 02025. Bibcode:2009yCat....102025S.
  3. 1 2 3 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: 0. Bibcode:2002yCat.2237....0D.
  4. ↑ Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data". Astronomy and Astrophysics. 430 (1): 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272.
  5. ↑ Wasatonic, R. & Guinan, E. F. (1998). "Variations of Luminosity, Radius, and Temperature of the Pulsating Red Supergiant CE Tauri". Information Bulletin on Variable Stars. 4629: 1. Bibcode:1998IBVS.4629....1W.
  6. 1 2 3 4 5 6 7 8 9 10 Montargès, M; Norris, R; Chiavassa, A; Tessore, B; Lèbre, A; Baron, F (2018). "The convective photosphere of the red supergiant CE Tau. I. VLTI/PIONIER H-band interferometric imaging". Astronomy & Astrophysics. 614: A12. arXiv:1802.06086. doi:10.1051/0004-6361/201731471.
  7. 1 2 3 4 Cruzalebes, P.; Jorissen, A.; Rabbia, Y.; Sacuto, S.; Chiavassa, A.; Pasquato, E.; Plez, B.; Eriksson, K.; Spang, A.; Chesneau, O. (2013). "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER". Monthly Notices of the Royal Astronomical Society. 434 (1): 437–450. arXiv:1306.3288. Bibcode:2013MNRAS.434..437C. doi:10.1093/mnras/stt1037.
  8. ↑ Beavers, W. I; Cadmus, R. R; Eitter, J. J (1982). "Lunar occultation stellar angular diameter measurements. III". The Astronomical Journal. 87: 818. Bibcode:1982AJ.....87..818B. doi:10.1086/113161.
  9. ↑ White, N. M (1980). "The occultation of 119 Tauri and the effective temperatures of three M supergiants". The Astrophysical Journal. 242: 646. Bibcode:1980ApJ...242..646W. doi:10.1086/158501.
  10. 1 2 White, N. M; Kreidl, T. J; Goldberg, L (1982). "An Occultation Angular Diameter in H-Alpha Light". The Astrophysical Journal. 254: 670. Bibcode:1982ApJ...254..670W. doi:10.1086/159778.
  11. ↑ Quirrenbach, A; Mozurkewich, D; Armstrong, J. T; Buscher, D. F; Hummel, C. A (1993). "Angular diameter measurements of cool giant stars in strong TiO bands and in the continuum". The Astrophysical Journal. 406: 215. Bibcode:1993ApJ...406..215Q. doi:10.1086/172432.
  12. ↑ Dyck, H. M; Benson, J. A; Van Belle, G. T; Ridgway, S. T (1996). "Radii and Effective Temperatures for K and M Giants and Supergiants". The Astronomical Journal. 111: 1705. Bibcode:1996AJ....111.1705D. doi:10.1086/117910.
  13. ↑ Dyck, H. M; Van Belle, G. T; Thompson, R. R (1998). "Radii and Effective Temperatures for K and M Giants and Supergiants. II". The Astronomical Journal. 116 (2): 981. Bibcode:1998AJ....116..981D. CiteSeerX 10.1.1.24.1889. doi:10.1086/300453.
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