Astronomy:HD 861
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cassiopeia[2] |
| Right ascension | 00h 13m 12.73037s[3] |
| Declination | +62° 02′ 27.1598″[3] |
| Apparent magnitude (V) | 6.622[4] |
| Characteristics | |
| Spectral type | A2m[5] + GV[6] |
| B−V color index | +0.208[4] |
| Astrometry | |
| Radial velocity (Rv) | 8.80±6.28[3] km/s |
| Proper motion (μ) | RA: 72.804[3] mas/yr Dec.: -19.171[3] mas/yr |
| Parallax (π) | 8.0883 ± 0.0269[3] mas |
| Distance | 403 ± 1 ly (123.6 ± 0.4 pc) |
| Absolute magnitude (MV) | 1.30 (A), 5.62 (B)[6] |
| Orbit[6] | |
| Primary | HD 861 A |
| Companion | HD 861 B |
| Period (P) | 15.9696 d |
| Eccentricity (e) | 0.124 |
| Details[6] | |
| HD 861 A | |
| Mass | 2.04 M☉ |
| Radius | 2.775 ± 0.139[7] R☉ |
| Surface gravity (log g) | 4.00 cgs |
| Temperature | 8100 K |
| Metallicity [Fe/H] | 0.44 dex |
| Rotational velocity (v sin i) | 37 km/s |
| Age | 724 Myr |
| HD 861 B | |
| Mass | 0.95 M☉ |
| Surface gravity (log g) | 4.5 cgs |
| Temperature | 5500 K |
| Other designations | |
| Database references | |
| SIMBAD | HD 861 |
HD 861 is a spectroscopic binary star system in the deep northern constellation of Cassiopeia. With an apparent magnitude of 6.622, the star is faintly visible to the naked eye under very dark skies and readily visible using binoculars.[8] It is located approximately 403 light-years (124 parsecs) distant according to Gaia DR3 parallax measurements, and is moving further away at a heliocentric radial velocity of 8.80 km/s.
Stellar properties
The primary star is a typical Am star, enriched in iron and especially so in barium but depleted in carbon, oxygen and calcium. At an age of 724 million (108.86) years, it is currently a main-sequence star fusing hydrogen into helium at its core. It will continue to do so for the next 320 million years until it runs out of core hydrogen at 1.05 billion (109.02) years old, at which point it will leave the main sequence and enter the subgiant phase.[6]
The secondary star is a G-type main-sequence star slightly less massive than the Sun and less than half as luminous.[6]
Orbit
The orbital properties of the companion were first determined in 1971 by Acker, with an orbital period of 11.2153 days and an eccentricity of 0.22.[9] In 2002, however, Debernardi found an entirely different set of orbital parameters in his PhD thesis and also discovered the stellar spectra of the secondary star. This new orbit has a longer period of 15.9696 days and a lower eccentricity of 0.124. This was backed up by Budaj et al.,[10] who also independently found the secondary spectra and obtained a mass ratio between the two stars that agreed with Debernardi's research.[6]
References
- ↑ 1.0 1.1 "HD 861". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+861.
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 4.0 4.1 Høg, E. et al. (February 2000). "The Tycho-2 Catalogue of the 2.5 Million Brightest Stars". Astronomy and Astrophysics 355 (1): L27–L30. Bibcode: 2000A&A...355L..27H.
- ↑ Abt, H.A. (2009). "MK classifications of spectroscopic binaries". VizieR On-line Data Catalog (Centre de Donnees Strasbourg (CDS)). doi:10.26093/CDS/VIZIER.21800117. Bibcode: 2009yCat..21800117A. https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/180/117. Retrieved 2024-11-05.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Iliev, I. K. et al. (2006-08-01). "Abundance analysis of Am binaries and search for tidally driven abundance anomalies - II. HD 861, HD 18778, HD 20320, HD 29479, HD 96528 and HD 108651". Monthly Notices of the Royal Astronomical Society (Oxford University Press (OUP)) 370 (2): 819–827. doi:10.1111/j.1365-2966.2006.10513.x. ISSN 0035-8711. Bibcode: 2006MNRAS.370..819I.
This article incorporates text from this source, which is available under the CC BY 4.0 license.
- ↑ Kervella, Pierre et al. (2019). "Stellar and substellar companions of nearby stars from Gaia DR2". Astronomy & Astrophysics (EDP Sciences) 623: A72. doi:10.1051/0004-6361/201834371. ISSN 0004-6361. Bibcode: 2019A&A...623A..72K. Record for this source at VizieR.
- ↑ Zarenski, Ed (2004). "Limiting Magnitude in Binoculars". Cloudy Nights. http://www.cloudynights.com/documents/limiting.pdf.
- ↑ Acker, A. (September 1971). "Orbital elements of the spectroscopic binaries HD 24733 and HD 861.". Astronomy & Astrophysics 14: 189. Bibcode: 1971A&A....14..189A.
- ↑ Budaj, J.; Iliev, I. Kh.; Fenovcik, M.; Barzova, I.; Richards, M. T.; Geordzheva, E. (12 March 2004). "Discovery of the Secondary in the Spectrum of the SB1 System HD 861". Information Bulletin on Variable Stars (International Astronomical Union) 5509 (1). ISSN 0374-0676. Bibcode: 2004IBVS.5509....1B.
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