RV Tauri

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RV Tauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 04h 47m 6.7281s[1]
Declination 26° 10′ 45.613″[1]
Apparent magnitude (V) 9.0–10.6[2]
Characteristics
Spectral type G2eIa-M2Ia[3]
U−B color index 0.9-1.8[2]
B−V color index 1.5-1.9[2]
Variable type RVb[4]
Astrometry
Radial velocity (Rv)32[5] km/s
Proper motion (μ) RA: -2.20[1] mas/yr
Dec.: -5.00[1] mas/yr
Parallax (π)1.21 ± 0.36[6] mas
Distance2,170[4] pc
Absolute magnitude (MV)-3.65[7]
Details
Mass0.6[8] M
Luminosity3,700[4] L
Surface gravity (log g)0.0[4] cgs
Temperature4,500[4] (4,225-5,080[2]K
Metallicity-0.4[4]
Other designations
RV Tauri, RV Tau, 2MASS J04470673+2610455, GSC 01835-01075, BD+25°732, HD 283868, TYC 1835-1075-1, GCRV 2803, AAVSO 0441+26, IRAS 04440+2605
Database references
SIMBADdata

RV Tauri (RV Tau) is a star in the constellation Taurus. It is a yellow supergiant and is the prototype of a class of pulsating variables known as RV Tauri variables.

Variability[edit]

RV Tau was discovered to be variable in 1905 by Lydia Ceraski,[9] and by 1907 it was clear that it had minima of alternating brightness.[10] Over a period of 78.5 days it shows two maxima at around magnitude 9.5, a minimum around magnitude 10.0, and another minimum about 0.5 magnitudes fainter.[11] This change in brightness is caused by pulsations: the temperature and radius vary, causing some variation in luminosity but mostly a shift of the emitted radiation from visual to infrared. The spectral type varies in line with the temperature, being classified as G2 at its brightest and M2 at its dimmest. In addition to the fundamental period given, RV Tauri also exhibits small variations in its mean brightness over a period of 1,216 days. The maxima and minima in each period vary by several tenths of a magnitude with no obvious regularity.[11]

Visibility[edit]

RV Tau is well placed for northern hemisphere observers during the winter months, and observations can be made from August to April. However it is faint, located in a nondescript patch of sky between The Pleiades and Beta Aurigae.[11]

Properties[edit]

The distance to RV Tau has been calculated by various methods, including modelling the atmosphere. RV Tauri stars have been shown to follow a period-luminosity relationship, and this can be used to confirm the luminosity and distance.[12] They have low masses, but are extended cool stars of high luminosity undergoing strong mass loss. RV Tau has a luminosity of 3,700 L but the spectral luminosity class of a bright supergiant, indicating the rarified nature of its atmosphere.

Surface abundances show enhancement of heavy elements, thought to have been dredged up during an earlier AGB phase. Carbon in particular is strongly in excess in RV Tau.[8]

RV Tau is surrounded by a dusty circumstellar disc, a common feature of RV Tauri variables. It has been suggested that the formation of the disk is related to a binary companion, but none has been detected.[4]

Evolution[edit]

RV Tau is likely a post-Asymptotic Giant Branch (AGB) star, an originally sun-like star which is in the end stages of its life just prior to the expulsion of a planetary nebula and contraction to a white dwarf. RV Tau gives an insight into the lives and deaths of stars like the Sun. Evolution models show it takes about 10 billion years for a 1 solar mass (1 M) star to reach the Asymptotic Giant Branch.[13]

References[edit]

  1. 1.0 1.1 1.2 1.3 Hog, E.; Kuzmin, A.; Bastian, U.; Fabricius, C.; Kuimov, K.; Lindegren, L.; Makarov, V. V.; Roeser, S. (1998). "The TYCHO Reference Catalogue". Astronomy and Astrophysics 335: L65. Bibcode 1998A&A...335L..65H.
  2. 2.0 2.1 2.2 2.3 Dawson, D. W. (1979). "A photometric investigation of RV Tauri and yellow semiregular variables". Astrophysical Journal Supplement Series 41: 97. Bibcode 1979ApJS...41...97D. doi:10.1086/190610.
  3. Taranova, O. G.; Shenavrin, V. I.; Tatarnikov, A. M. (2009). "Infrared photometry for two RV Tau stars and V1027 Cyg". Astronomy Letters 35 (7): 472. Bibcode 2009AstL...35..472T. doi:10.1134/S1063773709070044.
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Ruyter, S; Winckel; Dominik; Waters; Dejonghe (2005). "Strong dust processing in circumstellar discs around 6 RV Tauri stars. Are dusty RV Tauri stars all binaries?". Astronomy and Astrophysics 435 (1): 161–166. arXiv:astro-ph/0503290v1. Bibcode 2005A&A...435..161D. doi:10.1051/0004-6361:20041989.
  5. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington: 0. Bibcode 1953GCRV..C......0W.
  6. Gaia Collaboration (2016). "VizieR Online Data Catalog: Gaia DR1 (Gaia Collaboration, 2016)". VizieR On-line Data Catalog: I/337. Originally published in: Astron. Astrophys 1337. Bibcode 2016yCat.1337....0G.
  7. Wahlgren, Glenn M. (1992). "The metallicity and luminosity of RV Tauri variables from medium-resolution spectra". Astronomical Journal 104: 1174. Bibcode 1992AJ....104.1174W. doi:10.1086/116306.
  8. 8.0 8.1 Stasińska, G.; Szczerba, R.; Schmidt, M.; Siódmiak, N. (2006). "Post-AGB stars as testbeds of nucleosynthesis in AGB stars". Astronomy and Astrophysics 450 (2): 701. arXiv:astro-ph/0601504. Bibcode 2006A&A...450..701S. doi:10.1051/0004-6361:20053553.
  9. Ceraski, W. (1905). "Trois nouvelles variables". Astronomische Nachrichten 168 (2): 29. Bibcode 1905AN....168...29C. doi:10.1002/asna.19051680207.
  10. Seares, Frederick Hanley; Haynes, Eli Stuart (1908). "The Variable RV Tauri (45.1905)". Laws Observatory Bulletin 14: 215. Bibcode 1908LawOB..14..215S.
  11. 11.0 11.1 11.2 Isles, J. E. (1975). "Variable Star Section". Journal of the British Astronomical Society 85: 156. Bibcode 1975JBAA...85..156I.
  12. Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T. S.; Becker, A.; Bennett, D. P.; Cook, K. H.; Freeman, K. C. et al. (1998). "The MACHO Project LMC Variable Star Inventory. VII. The Discovery of RV Tauri Stars and New Type II Cepheids in the Large Magellanic Cloud". The Astronomical Journal 115 (5): 1921. arXiv:astro-ph/9708039. Bibcode 1998AJ....115.1921A. doi:10.1086/300317.
  13. Bloecker, T. (1995). "Stellar evolution of low- and intermediate-mass stars. II. Post-AGB evolution". Astronomy and Astrophysics 299: 755. Bibcode 1995A&A...299..755B.


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