Tau2 Gruis
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| Observation data Epoch J2000.0 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 mas/yr[1] Dec.: +55.712 mas/yr[1] |
| Parallax (π) | 22.3461 ± 0.0241 mas[1] |
| Distance | 146.0 ± 0.2 ly (44.75 ± 0.05 pc) |
| Absolute magnitude (MV) | +3.43[7] (combined) |
| Details[8] | |
| A | |
| Mass | 1.21 M☉ |
| B | |
| Mass | 1.16 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
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[11] 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.[12] 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,[13] but it is estimated to be 7.423 years.[8] Subsequent observations suggest that the pair may be spurious.[13] This system is often confused with HD 216655, a slightly brighter binary system.[14] 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
- ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361. S2CID 17128864.
- ^ a b c d 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. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256. S2CID 119533755.
- ^ a b Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. Vol. 2. Bibcode:1978mcts.book.....H.
- ^ 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. S2CID 118805499.
- ^ a b Nordström, B.; Mayor, M.; Andersen, J.; Holmberg, J.; Pont, F.; Jørgensen, B. R.; Olsen, E. H.; Udry, S.; Mowlavi, N. (16 April 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood". Astronomy & Astrophysics. 418 (3): 989–1019. arXiv:astro-ph/0405198. Bibcode:2004A&A...418..989N. doi:10.1051/0004-6361:20035959. eISSN 1432-0746. ISSN 0004-6361. S2CID 11027621.
- ^ a b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
- ^ a b c d Tokovinin, Andrei (14 March 2014). "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs". The Astronomical Journal. 147 (4): 87. arXiv:1401.6827. Bibcode:2014AJ....147...87T. doi:10.1088/0004-6256/147/4/87. eISSN 1538-3881. ISSN 0004-6256.
- ^ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
- ^ "HD 216655". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-24.
{{cite web}}: CS1 maint: postscript (link) - ^ 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. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
- ^ 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.
- ^ a b Tokovinin, Andrei (February 23, 2023). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5. ISSN 0067-0049. S2CID 119047709.
- ^ 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. p. 162. ISBN 978-0-939923-78-6.
