Astronomy:Tau2 Gruis

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Short description: Double star in the constellation Grus


For other stars with this Bayer designation, see τ Gruis.
Tau2 Gruis
Observation data
Equinox J2000.0]] (ICRS)
Constellation Grus
Right ascension  22h 55m 15.99534s[1]
Declination −48° 29′ 30.30277″[1]
Apparent magnitude (V) 6.71[2] (7.30+ 7.50)[3]
Characteristics
Spectral type F6/8 V:[4]
B−V color index +0.46[5]
Astrometry
Radial velocity (Rv)0.7±0.3[6] km/s
Proper motion (μ) RA: −225.658[1] mas/yr
Dec.: +55.712[1] mas/yr
Parallax (π)22.3461 ± 0.0241[1] mas
Distance146.0 ± 0.2 ly
(44.75 ± 0.05 pc)
Absolute magnitude (MV)+3.43[7] (combined)
Details[8]
A
Mass1.21 M☉
B
Mass1.16 M☉
Other designations
τ2 Gru, CD−49° 13997, CPD−49°11676, GC 31952, HD 216656, HIP 113190, SAO 231353, WDS J22553-4828CD[9]
Database references
SIMBADdata

Tau2 Gruis, Latinized from τ2 Gruis is a binary star located in the constellation Grus. It has a combined apparent magnitude of 6.71,[2] making it a challenge to view with the naked eye, even under ideal conditions. The system is located relatively close at a distance of 146 light-years based on Gaia DR3 parallax measurements, but it is slowly receding with a heliocentric radial velocity of 0.7 km/s.[6] At its current distance, Tau2 Gruis' combined brightness is diminished by an interstellar extinction of 0.12 magnitudes[10] and it has a combined absolute magnitude of +3.43.[7]

The pair was first discovered by astronomer W.H. van den Bos in 1944.[11] The primary has an apparent magnitude of 7.30 while the secondary has an apparent magnitude of 7.50.[3] Their current separation is 0.114",[8] making it difficult to resolve their individual properties; the companion is located at a position angle of 267° as of 1964.[3] The period of Tau2 Gruis is not well known,[12] but it is estimated to be 7.423 years.[8] Subsequent observations suggest that the pair may be spurious.[12] This system is often confused with HD 216655, a slightly brighter binary system.[13] HD 216655 is located 93.9" away from Tau2 Gruis and they appear to share a common proper motion.[3]

The system has a blended stellar classification of F6/8 V:,[4] indicating that it is a F-type star with the characteristics of a F6 and F8 main sequence star. However, there is uncertainty about the luminosity class. The primary has 1.21 times the mass of the Sun while the companion has 1.16 times the mass of the Sun.[8]

References

  1. ↑ 1.0 1.1 1.2 1.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 3.2 3.3 Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M. 
  4. ↑ 4.0 4.1 Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. 2. Bibcode: 1978mcts.book.....H. 
  5. ↑ Cousins, A. W. J.; Stoy, R. H. (1962). "Photoelectric magnitudes and colours of Southern stars.". Royal Greenwich Observatory Bulletins 64: 103. Bibcode: 1962RGOB...64..103C. 
  6. ↑ 6.0 6.1 Nordström, B.; Mayor, M.; Andersen, J.; Holmberg, J.; Pont, F.; Jørgensen, B. R.; Olsen, E. H.; Udry, S. et al. (16 April 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood". Astronomy & Astrophysics 418 (3): 989–1019. doi:10.1051/0004-6361:20035959. ISSN 0004-6361. Bibcode: 2004A&A...418..989N. 
  7. ↑ 7.0 7.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 8.2 8.3 Tokovinin, Andrei (14 March 2014). "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs". The Astronomical Journal 147 (4): 87. doi:10.1088/0004-6256/147/4/87. ISSN 0004-6256. Bibcode: 2014AJ....147...87T. 
  9. ↑ "HD 216655". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+216655. 
  10. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  11. ↑ van den Bos, W. H. (September 1947). "Measures of Double Stars-25th Series". Circular of the Union Observatory Johannesburg 105: 134–171. Bibcode: 1947CiUO..105..134V. 
  12. ↑ 12.0 12.1 Tokovinin, Andrei (February 23, 2023). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series 235 (1): 6. doi:10.3847/1538-4365/aaa1a5. ISSN 0067-0049. Bibcode: 2018ApJS..235....6T. 
  13. ↑ Wagman, Morton (2003). Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others. Blacksburg, VA: The McDonald & Woodward Publishing Company. pp. 162. ISBN 978-0-939923-78-6. 
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External links



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