HD 161988, also known as HR 6635, is a solitary, orange hued star located in the southern circumpolar constellation Apus. It has an apparent magnitude of 6.07,[2] allowing it to be faintly visible to the naked eye. Parallax measurements place it at a distance of 621 light years,[1] and it is currently receding with a heliocentric radial velocity of 36.8 km/s.[6]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Apus |
| Right ascension | 17h 57m 41.686s[1] |
| Declination | −76° 10′ 40.62″[1] |
| Apparent magnitude (V) | 6.07±0.01[2] |
| Characteristics | |
| Evolutionary stage | red giant branch[3] |
| Spectral type | K2 III[4] |
| U−B color index | +1.28[5] |
| B−V color index | +1.20[5] |
| Astrometry | |
| Radial velocity (Rv) | +36.8±0.4[6] km/s |
| Proper motion (μ) | RA: +2.464 mas/yr[1] Dec.: −1.867 mas/yr[1] |
| Parallax (π) | 5.2546 ± 0.022 mas[1] |
| Distance | 621 ± 3 ly (190.3 ± 0.8 pc) |
| Absolute magnitude (MV) | −0.26[7] |
| Details | |
| Mass | 3.05[8] M☉ |
| Radius | 20.8[9] R☉ |
| Luminosity | 185[10] L☉ |
| Surface gravity (log g) | 2.04±0.02[3] cgs |
| Temperature | 4,498[10] K |
| Metallicity [Fe/H] | −0.13[11] dex |
| Rotational velocity (v sin i) | 2.1±1.3[12] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
The object has a stellar classification of K2 III,[4] indicating that it is a red giant. Gaia Data Release 3 models place it on the red giant branch. At present it has 3.05 times the mass of the Sun[8] and an enlarged radius of 20.8 R☉.[9] It shines at 185 times the luminosity of the Sun from its photosphere at an effective temperature of 4,498 K.[10] HD 161988 has an iron abundance 74% that of the Sun,[11] making it slightly metal deficient. Like most giants, it spins modestly with a projected rotational velocity of 2.1 km/s.[12]
HD 161988 has a 14th magnitude optical companion located 26.4 arcseconds away along a position angle of 122°.[15]
References
edit- ^ a b c d e 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 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 Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations −90° to −53°. Bibcode:1975mcts.book.....H.
- ^ a b Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99): 99. Bibcode:1966CoLPL...4...99J.
- ^ 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. 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. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
- ^ a b Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (2022). "Stellar and substellar companions from Gaia EDR3". Astronomy & Astrophysics. 657: A7. arXiv:2109.10912. Bibcode:2022A&A...657A...7K. doi:10.1051/0004-6361/202142146. eISSN 1432-0746. ISSN 0004-6361.
- ^ a b Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881.
- ^ a b c 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 Anders, F.; et al. (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. eISSN 1432-0746. ISSN 0004-6361.
- ^ 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.
- ^ 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.
- ^ "HR 6635". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved August 15, 2022.
- ^ 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.