Nu Tucanae

ν Tucanae, Latinized as Nu Tucanae, is a solitary,[10] variable star in the southern constellation of Tucana. This red-hued object is visible to the naked eye as a faint star with an apparent visual magnitude that fluctuates around +4.80.[4] It is located approximately 290 light years from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −3 km/s.[6]

Nu Tucanae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Tucana
Right ascension  22h 33m 00.06240s[1]
Declination −61° 58′ 55.6390″[1]
Apparent magnitude (V) 4.75 - 4.93[2]
Characteristics
Spectral type M4 III[3]
U−B color index +1.73[4]
B−V color index +1.61[4]
Variable type Lb:[5]
Astrometry
Radial velocity (Rv)−3.4±0.8[6] km/s
Proper motion (μ) RA: −3.40[1] mas/yr
Dec.: −0.8[1] mas/yr
Parallax (π)11.24 ± 0.23[1] mas
Distance290 ± 6 ly
(89 ± 2 pc)
Absolute magnitude (MV)+0.16[7]
Details
Radius49.39+5.65
−7.73[8] R☉
Luminosity400±11[8] L☉
Temperature3,674+326
−194[8] K
Other designations
ν Tuc, CPD−62°6348, FK5 3803, HD 213442, HIP 111310, HR 8582, SAO 255247[9]
Database references
SIMBADdata

This object is an aging red giant with a stellar classification of M4 III,[3] currently on the asymptotic giant branch.[5] With the supply of hydrogen exhausted at its core, the star has cooled and expanded off the main sequence; at present it has 49 times the Sun's radius.[8] It is classified as a slow irregular variable and its brightness varies from magnitude +4.75 to +4.93.[2] Cyclical periods of 22.3, 24.4, 24.8, 25.1, 25.5, 33.8, 50.6, 80.1, 123.2, and 261.8 days have been reported for its variations.[11] On average, the star is radiating around 400[8] times the luminosity of the Sun from its photosphere at an effective temperature of 3,674 K.[8]

References
  1. 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. Samus, N. N.; Durlevich, O. V.; et al. (2009), "General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S, 1, Bibcode:2009yCat....102025S.
  3. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Cousins, A. W. J. (1964), "Photometric Data for Stars in the Equatorial Zone (Seventh List)", Monthly Notes of the Astronomical Society of Southern Africa, 23: 175, Bibcode:1964MNSSA..23..175C.
  5. Sloan, G. C.; Price, S. D. (December 1998), "The Infrared Spectral Classification of Oxygen-rich Dust Shells", The Astrophysical Journal Supplement Series, 119 (2): 141–158, Bibcode:1998ApJS..119..141S, doi:10.1086/313156.
  6. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065.
  7. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  8. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  9. "nu Tuc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-04.
  10. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  11. Tabur, V.; Bedding, T. R.; et al. (2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x.
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