119 Tauri

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Template:Short description

119 Tauri
File:119 Tauri(english)new.png
The sky position of 119 Tauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.23 - 4.54[2]
Characteristics
Evolutionary stage Red supergiant star, or possible asymptotic giant branch star[3]
Spectral type M2Iab-Ib[2]
U−B Template:Engvar +2.23[4]
B−V Template:Engvar +2.08[4]
Variable type SRc[2]
Astrometry
Radial velocity (Rv)+23.75[5] km/s
Proper motion (μ) RA: 1.86[1] mas/yr
Dec.: −4.48[1] mas/yr
Parallax (π)1.82±0.26 mas[1]
Distanceapprox. Template:Rnd ly
(approx. Template:Rnd pc)
Absolute magnitude (MV)−5.20[6]
Details
MassTemplate:Val[7] Template:Solar mass
Radius587 - 593[7] Template:Solar radius
Luminosity66,000[7] Template:Solar luminosity
Surface gravity (log g)Template:Val[7] cgs
Temperature3,801 - 3,820[7] K
Metallicity0.0[3]
AgeTemplate:Val[7] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
CE Tauri, HR 1845, HD 36389, BD+18°875, HIP 25945, SAO 94628, GC 6841, AAVSO 0526+18, Ruby Star[8]
Database references
SIMBADdata

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119 Tauri (also known as CE Tauri) is a red supergiant star in the constellation Taurus. It is a magnitude 4 star, visible to the naked eye under good observing conditions. A semiregular variable, its angular diameter has been measured at about Template:Val. It is a similar star to Betelgeuse although redder and more distant.[6]

Description

File:CETauLightCurve.png
A light curve for CE Tauri, plotted from Hipparcos data[9]

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, and with a colour index of +2.07 it is one of the reddest naked eye stars in the night sky.[4]

119 Tauri is classified as a semiregular variable star and has been given the variable star designation CE Tauri. The General Catalogue of Variable Stars gives a magnitude range from +4.23 to +4.54 with a period of 165 days.[2] Other published studies find poorly-defined periodicity, but with possible periods around 270 and 1,300 days.[10][11][12] Its infrared magnitude changes much less than the visual magnitude; the visual brightness changes are driven by changes in temperature which shift the proportion of electromagnetic radiation emitted in the visual range.[6]

File:Superzoom.Rubinstern.119.Tauri.webm
The head of the bull in the constellation Taurus in the upper right corner with the open star cluster of the Hyades and the bright star Aldebaran (α Tauri, 0,8m). On the left the two tips of the bull's horns Elnath (β Tauri, 1,6m, at the top, north of the ecliptic) and Tien Kuan (ζ Tauri, 2,9m, at the bottom, south of the ecliptic). A little bit below and right the Red Giant 119 Tauri (4,3m).

Occultations

CE Tauri lies 4.6 degrees off the ecliptic.[13] 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 Template:Val,[14] Template:Val,[15] and Template:Val.[16] An occultation has also been observed in H-alpha, giving a diameter of Template:Val, which indicates that there is circumstellar hydrogen producing emission across at least that size, nearly twice the visible diameter.[16]

Angular diameter

The angular diameter of 119 Tauri has also been measured directly by VLBI, leading to limb-darkened diameters of Template:Val,[17] Template:Val,[18] Template:Val,[19] Template:Val,[3] Template:Val,[7] Template:Val.[7] 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.[3] Reconstructed images of the surface show bright spots that are attributed to giant convection cells.[7]

Properties

Angular diameter measurements can be combined with absolute observed fluxes to derive an accurate effective temperature, about 3,800 K for 119 Tauri. Combined with a distance, the linear size of the star can be calculated. CE Tauri is found to have a radius between Template:Solar radius. Then the bolometric luminosity is the star is found to be about Template:Solar luminosity. However, the distance to 119 Tauri is still only known approximately from its Hipparcos parallax. Gaia Data Release 2 gives a distinctly larger parallax, but with even greater uncertainty and flagged as unreliable.[20]

119 Tauri is a pulsating star although the pulsation has not been clearly detected in direct angular measurements. Observations of TiO lines in its spectrum as its brightness changes show effective temperature changes up to Template:Val. Calculating its physical properties shows that the bolometric luminosity and radius both change by about 10%, with the radius typically being larger at cooler temperatures.[6]

Comparison of its properties with stellar evolutionary tracks shows CE Tauri to have evolved from an initial mass of Template:Solar mass and to have a current mass of Template:Solar mass.[7] An alternative interpretation of observations, under the assumption that CE Tauri is an asymptotic giant branch (AGB) star, give it a current mass of Template:Solar mass and a luminosity of Template:Solar luminosity.[3]

References

Template:Reflist

Template:Stars of Taurus

  1. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named hipparcos
  2. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named gcvs
  3. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named vlti
  4. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named ducati
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named FamaeyJorissen2005
  6. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named wasatonic
  7. ↑ a b c d e f g h i j Cite error: Invalid <ref> tag; no text was provided for refs named montarges
  8. ↑ Script error: No such module "Citation/CS1".
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named HipDataAccess
  10. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named percy
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kiss
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named percy2008
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named ecliptic
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named beavers
  15. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named white1980
  16. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named white1982
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named quirrenbach
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named dyck1996
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named dyck1998
  20. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named dr2
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