HD 179886 (HR 7289) is a binary star[3] located in the southern constellation Telescopium. It has a combined apparent magnitude of 5.37,[2] making it faintly visible to the naked eye if viewed under ideal conditions. The system is situated at a distance of 700 light years[1] but is receding with a heliocentric radial velocity of 6.3 km/s.[6]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Telescopium |
| Right ascension | 19h 16m 21.7422s[1] |
| Declination | −45° 27′ 57.704″[1] |
| Apparent magnitude (V) | 5.371[2] (5.59 + 8.63)[3] |
| Characteristics | |
| Evolutionary stage | red giant branch[1] |
| Spectral type | K3 III[4] |
| B−V color index | +1.35[5] |
| Astrometry | |
| Radial velocity (Rv) | 6.3±0.8[6] km/s |
| Proper motion (μ) | RA: −3.013[1] mas/yr Dec.: +10.017[1] mas/yr |
| Parallax (π) | 4.6441 ± 0.1537 mas[1] |
| Distance | 700 ± 20 ly (215 ± 7 pc) |
| Absolute magnitude (MV) | −0.7[7] |
| Details | |
| Mass | 1.11[8] M☉ |
| Radius | 36.75[9] R☉ |
| Luminosity | 365[10] L☉ |
| Surface gravity (log g) | 1.3[8] cgs |
| Temperature | 4,622[10] K |
| Metallicity [Fe/H] | +0.15[8] dex |
| Rotational velocity (v sin i) | 2.4±1.1[11] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
As of 2018, the two stars have a separation of 0.4 arcseconds along a position angle of 205°[12]
The brighter component has a stellar classification of K3 III, indicating that the object is an ageing K-type giant. Models show it to be on the red giant branch,[1] a stage of stellar evolution where the star is fusing hydrogen in a shell around an inert core of helium. It has an angular diameter of 1.95±0.03,[13] yielding a diameter 37 times that of the Sun[9] at its estimated distance. At present it has 111% the mass of the Sun[8] and radiates at 365 L☉[10] from its enlarged photosphere at an effective temperature of 4,622 K,[10] giving it an orange glow. HD 179886A has a metallicity 141% that of the Sun[8] and spins modestly with a projected rotational velocity of 2.4 km/s.[11]
References
edit- ^ a b c d e f g h Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 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.
- ^ a b 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. S2CID 14878976.
- ^ Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Bibcode:1978mcts.book.....H.
- ^ Corben, P. M. (1971). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of South Africa. 30: 37. Bibcode:1971MNSSA..30...37C. ISSN 0024-8266.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1063-7737. S2CID 119231169.
- ^ 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. ISSN 1063-7737. S2CID 255204555.
- ^ a b c d e Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A.; Matijevič, G.; Monari, G.; Cantat-Gaudin, T.; Weiler, M.; Khan, S.; Miglio, A.; Carrillo, I.; Romero-Gómez, M.; Minchev, I.; de Jong, R. S.; Antoja, T.; Ramos, P.; Steinmetz, M.; Enke, H. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. ISSN 0004-6361.
- ^ a b 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.
- ^ a b c d McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. ISSN 0035-8711.
- ^ a b De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars: V. Southern stars⋆⋆⋆". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. ISSN 0004-6361.
- ^ 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.
- ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005). "CHARM2: An updated Catalog of High Angular Resolution Measurements". Astronomy & Astrophysics. 431 (2): 773–777. Bibcode:2005A&A...431..773R. doi:10.1051/0004-6361:20042039. ISSN 0004-6361.