HR 6801
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 11m 43.33342s[1] |
| Declination | −23° 42′ 04.4346″[1] |
| Apparent magnitude (V) | 4.96[2] |
| Characteristics | |
| Spectral type | K0III[3] |
| U−B color index | +0.90[4] |
| B−V color index | +1.05[4] |
| Astrometry | |
| Radial velocity (Rv) | +5.71±0.20[1] km/s |
| Proper motion (μ) | RA: +9.337[1] mas/yr Dec.: −31.999[1] mas/yr |
| Parallax (π) | 12.6303 ± 0.2449 mas[1] |
| Distance | 258 ± 5 ly (79 ± 2 pc) |
| Absolute magnitude (MV) | 0.49[2] |
| Details | |
| Mass | 2.24[5] M☉ |
| Radius | 13.35+0.14 −0.92[1] R☉ |
| Luminosity | 78.6±1.7[1] L☉ |
| Surface gravity (log g) | 2.65[5] cgs |
| Temperature | 4,705+171 −25[1] K |
| Metallicity [Fe/H] | 0.00[5] dex |
| Rotational velocity (v sin i) | 1.6[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
HR 6801 is a single[8] star in the southern zodiac constellation of Sagittarius. It was designated as 1 Sagittarii by Flamsteed, but is now often referred to as 11 Sagittarii. Flamsteed's 11 Sgr actually refers to a different, much fainter star.[9] The object is orange in hue and is visible to the naked eye as a faint point of light with an apparent visual magnitude of 4.96.[2] The distance to this star is approximately 258 light years based on stellar parallax, and it is drifting further away with a radial velocity of +6 km/s.[1]
This is an aging giant star with a stellar classification of K0III.[10] It is a red clump giant,[11] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star has 2.24[5] times the mass of the Sun and has expanded to 13.4 times the Sun's radius. It is radiating 79 times the luminosity of the Sun from its photosphere at an effective temperature of 4,705 K.[1]
A faint visual companion, component B, has magnitude 11.51 and an angular separation of 43.7″.[12]
References
[edit]- ^ a b c d e f g h i j k 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 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.
- ^ Houk, Nancy; Smith-Moore, M. (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 4. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1988mcts.book.....H.
- ^ a b Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.
- ^ a b c d Liu, Y. J.; et al. (2007). "The abundances of nearby red clump giants". Monthly Notices of the Royal Astronomical Society. 382 (2): 553. Bibcode:2007MNRAS.382..553L. doi:10.1111/j.1365-2966.2007.11852.x.
- ^ De Medeiros, J. R.; et al. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. S2CID 54046583.
- ^ "11 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-12-07.
- ^ 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.
- ^ Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy. 18 (3): 212. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305. S2CID 118445625.
- ^ Hoffleit, D.; Warren, W. H. (1995). "Bright Star Catalogue". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050 (5th Revised ed.). Bibcode:1995yCat.5050....0H.
- ^ Alves, David R. (August 2000). "K-Band Calibration of the Red Clump Luminosity". The Astrophysical Journal. 539 (2): 732–741. arXiv:astro-ph/0003329. Bibcode:2000ApJ...539..732A. doi:10.1086/309278. S2CID 16673121.
- ^ Mason, Brian D.; et al. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
