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Eta Tucanae
Location of η Tucanae (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Tucana
Right ascension 23h 57m 35.07852s [1]
Declination −64° 17′ 53.6229″ [1]
Apparent magnitude (V) +5.00 [2]
Characteristics
Spectral type A1V [2]
U−B color index +0.08 [3]
B−V color index +0.06 [3]
Astrometry
Radial velocity (Rv)+32.50 [4] km/s
Proper motion (μ) RA: +78.850 [1]  mas/ yr
Dec.: −62.049 [1]  mas/ yr
Parallax (π)21.2425 ± 0.3639  mas [1]
Distance154 ± 3  ly
(47.1 ± 0.8  pc)
Absolute magnitude (MV)1.62 [5]
Details
Mass1.94 [6]  M☉
Radius1.8 [7]  R☉
Luminosity23 [8]  L☉
Surface gravity (log g)4.31 [9]  cgs
Temperature9,057 [8]  K
Rotational velocity (v sin i)190 [6] km/s
Other designations
η Tuc, CPD–64° 4391, FK5 2026, GC 33223, HD 224392, HIP 118121, HR 9062, SAO 255609, GSC 09130-01766 [10]
Database references
SIMBAD data

Eta Tucanae, Latinized from η Tucanae, is a probable binary star [6] system in the southern constellation of Tucana, a few degrees to the north of Epsilon Tucanae. It is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of +5.00. [2] parallax measurements provide a distance estimate of about 154  light years from the Sun, and it is drifting further away with a mean radial velocity of +32.5 km/s. [4] It is a member of the 30 million year old Tucana-Horologium association of co-moving stars. [6] [2]

The radial velocity for Eta Tucanae displays strong oscillations, suggesting this is a spectroscopic binary system. A companion was directly detected in 2014, but this result has some unexplained anomalies. [6] The primary component is an A-type main-sequence star with a stellar classification of A1V. [2] It is spinning rapidly with a projected rotational velocity of 190 km/s, [6] giving it an equatorial bulge that is 15% larger than the polar radius. [11] The star has 1.9 [6] times the mass of the Sun and 1.8 [7] times the Sun's radius. It is radiating 23 [8] times the luminosity of the Sun from its photosphere at an effective temperature of 9,057 K. [8]

References

  1. ^ a b c d e 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.
  2. ^ a b c d e Ehrenreich, D.; et al. (November 2010), "Deep infrared imaging of close companions to austral A- and F-type stars", Astronomy and Astrophysics, 523: A73, arXiv: 1007.0002, Bibcode: 2010A&A...523A..73E, doi: 10.1051/0004-6361/201014763, S2CID  54913363
  3. ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode: 2014JAVSO..42..443M. Vizier catalog entry
  4. ^ a b Kharchenko, N. V.; et al. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv: 0705.0878. Bibcode: 2007AN....328..889K. doi: 10.1002/asna.200710776. S2CID  119323941.
  5. ^ 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. S2CID  119257644. Vizier catalog entry
  6. ^ a b c d e f g Borgniet, S.; Lagrange, A. -M.; Meunier, N.; Galland, F. (March 2017). "Extrasolar planets and brown dwarfs around AF-type stars. IX. The HARPS southern sample". Astronomy & Astrophysics. 599: 26. arXiv: 1608.08257. Bibcode: 2017A&A...599A..57B. doi: 10.1051/0004-6361/201628805. S2CID  118723455. A57.
  7. ^ a b Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv: astro-ph/9911002. Bibcode: 1999A&A...352..555A. Vizier catalog entry
  8. ^ a b c d Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv: 1201.2052. Bibcode: 2012A&A...537A.120Z. doi: 10.1051/0004-6361/201117691. S2CID  55586789. Vizier catalog entry
  9. ^ David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv: 1501.03154. Bibcode: 2015ApJ...804..146D. doi: 10.1088/0004-637X/804/2/146. S2CID  33401607. Vizier catalog entry
  10. ^ "eta Tuc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-28.{{ cite web}}: CS1 maint: postscript ( link)
  11. ^ van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv: 1204.2572. Bibcode: 2012A&ARv..20...51V. doi: 10.1007/s00159-012-0051-2. S2CID  119273474.
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