HD 189276
HD 189276 is a single[4] star in the northern constellation Cygnus, positioned near the northern constellation border with Draco. It has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.98.[2] The star is located at a distance of approximately 820 light years from the Sun based on parallax, and it has an absolute magnitude of −2.25.[2] It is drifting further away with a radial velocity of +4 km/s.[2] The star has a high peculiar velocity of 38.5+1.8
−2.2 km/s and thus is a probable runaway star.[9]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 55m 55.37920s[1] |
| Declination | +58° 50′ 45.4752″[1] |
| Apparent magnitude (V) | 4.98[2] |
| Characteristics | |
| Spectral type | K4.5IIIa[3] or K5II-III[4] |
| B−V color index | 1.584±0.011[2] |
| Astrometry | |
| Radial velocity (Rv) | +4.26±0.34[2] km/s |
| Proper motion (μ) | RA: −8.953[1] mas/yr Dec.: −20.206[1] mas/yr |
| Parallax (π) | 3.9850 ± 0.1065[1] mas |
| Distance | 820 ± 20 ly (251 ± 7 pc) |
| Absolute magnitude (MV) | −2.25[2] |
| Details | |
| Mass | 4.05±0.56[5] M☉ |
| Radius | 178.11[6] R☉ |
| Luminosity | 1,533±49[1] L☉ |
| Surface gravity (log g) | 1.70[6] cgs |
| Temperature | 3,940+198 −30[1] K |
| Metallicity [Fe/H] | −0.1[7] dex |
| Rotational velocity (v sin i) | 1.7[7] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an aging star on the red giant branch[6] with a stellar classification of K4.5IIIa.[3] With the supply of hydrogen at its exhausted, it has cooled and expanded to 178[6] times the girth of the Sun. This is an active star that appears to be approaching the tip of the red-giant branch. Interferometric measurements of the star suggest significant departures from symmetry.[6] HD 189276 has four[5] times the mass of the Sun and is radiating 1,533 times the Sun's luminosity from its bloated photosphere at an effective temperature of 3,940.[1]
References
- 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.
- 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.
- Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
- 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.
- Hohle, M. M.; et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355.
- Chiavassa, A.; et al. (April 2017), "Asymmetries on red giant branch surfaces from CHARA/MIRC optical interferometry", Astronomy & Astrophysics, 600: 5, arXiv:1703.02406, Bibcode:2017A&A...600L...2C, doi:10.1051/0004-6361/201730438, L2.
- Lèbre, A.; et al. (May 2006), "Lithium abundances and rotational behavior for bright giant stars", Astronomy and Astrophysics, 450 (3): 1173–1179, Bibcode:2006A&A...450.1173L, doi:10.1051/0004-6361:20053485.
- "HD 189276". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-10.
- Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.