119 Tauri

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119 Tauri
119 Tauri(english)new.png
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
Distance approx. 1,800 ly
(approx. 550 pc)
Absolute magnitude (MV) −5.20[5]
Details
Mass 14.37+2.00
−2.77
[6] M
Radius 587 - 593[6] R
Luminosity 66,000[6] L
Surface gravity (log g) +0.05+0.11
−0.17
[6] cgs
Temperature 3,801 - 3,820[6] K
Metallicity 0.0[7]
Age 13.9+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
SIMBAD data

119 Tauri (CE Tauri) is a star in the constellation Taurus. It has a diameter about 600 times that of the Sun. CE Tauri is close enough that its distance can be determined accurately by parallax and so the actual diameter can be determined directly from the angular diameter.

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]

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]

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 nearly 60 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[edit]

  1. ^ a b c d e Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d 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. ^ a b c 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/0409579Freely accessible. 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. ^ a b c d e f g h i j 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". arXiv:1802.06086Freely accessible [astro-ph.SR]. 
  7. ^ a b c d 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:1306.3288Freely accessible. 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. ^ a b 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 10.1.1.24.1889Freely accessible. doi:10.1086/300453.