Astronomy:Gamma Coronae Australis
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Corona Australis |
| Right ascension | 19h 06m 25.11014s[1] |
| Declination | −37° 03′ 48.3901″[1] |
| Apparent magnitude (V) | 4.20[2] |
| Characteristics | |
| Spectral type | F8V + F8V[3] |
| U−B color index | +0.51[4] |
| B−V color index | +0.01[4] |
| Astrometry | |
| Radial velocity (Rv) | −51.60±0.3[5] km/s |
| Proper motion (μ) | RA: 96.74±1.05[1] mas/yr Dec.: −281.71±0.58[1] mas/yr |
| Parallax (π) | 57.79 ± 0.75[1] mas |
| Distance | 56.4 ± 0.7 ly (17.3 ± 0.2 pc) |
| Absolute magnitude (MV) | 3.73 / 3.80[6] |
| Orbit[7] | |
| Period (P) | 121.76 yr |
| Semi-major axis (a) | 1.896″ |
| Eccentricity (e) | 0.320 |
| Inclination (i) | 149.6° |
| Longitude of the node (Ω) | 50.3° |
| Periastron epoch (T) | 2000.64 |
| Argument of periastron (ω) (secondary) | 349.0° |
| Details[6] | |
| γ CrA A | |
| Mass | 1.15 M☉ |
| Radius | 1.47 R☉ |
| Surface gravity (log g) | 4.17 cgs |
| Temperature | 6,090 K |
| Metallicity [Fe/H] | −0.07 dex |
| Age | 5 Gyr |
| γ CrA B | |
| Mass | 1.14 M☉ |
| Radius | 1.42 R☉ |
| Surface gravity (log g) | 4.19 cgs |
| Temperature | 6,100 K |
| Age | 5 Gyr |
| Other designations | |
| γ CrA A: HD 177474, HR 7226[8] | |
| γ CrA B: HD 177475, HR 7227[9] | |
| Database references | |
| SIMBAD | γ CrA |
| γ CrA A | |
| γ CrA B | |
Gamma Coronae Australis (γ CrA), is a binary star located in the constellation Corona Australis. The system has a combined apparent visual magnitude of 4.20,[2] making it faintly visible to the naked eye. It is located 56.4 light-years (17.3 parsecs) from the Sun, based on its parallax.[1] Gamma Coronae Australis is a member of the Milky Way's thin disk.[6]
The system is a visual binary, where the orbit is calculated from observations of one star orbiting the other. The primary, Gamma Coronae Australis A, is a late F-type main-sequence star with an effective temperature of 6,090 K.[6] It has an absolute an absolute magnitude of +3.73, and a mass of 1.15 solar masses.[6] The secondary, Gamma Coronae Australis B, is also F-type. With an effective temperature of 6,100 K, an absolute magnitude of +3.80, and a mass of 1.14 solar masses, the companion is almost identical to the primary.[6] Gamma Coronae Australis has been known to be a binary for a long time, and its two components have been given Henry Draper Catalogue designations of HD 177474[8] and HD 177475,[9] respectively. The two stars are separated by 1.896″ and orbit each other every 121.76 years.[7]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 "* gam CrA". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+gam+CrA.
- ↑ Eggl, S.; Pilat-Lohinger, E.; Funk, B.; Georgakarakos, N.; Haghighipour, N. (2012). "Circumstellar habitable zones of binary-star systems in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society 428 (4): 3104. doi:10.1093/mnras/sts257. Bibcode: 2013MNRAS.428.3104E.
- ↑ 4.0 4.1 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode: 1986EgUBV........0M. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1.
- ↑ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Fuhrmann, K.; Chini, R. (2015). "Multiplicity Among F-Type Stars. II". The Astrophysical Journal 809 (1): 107. doi:10.1088/0004-637X/809/1/107. Bibcode: 2015ApJ...809..107F.
- ↑ 7.0 7.1 "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6. Retrieved 20 June 2017.
- ↑ 8.0 8.1 "* gam CrA A". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+gam+CrA+A.
- ↑ 9.0 9.1 "* gam CrA B". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+gam+CrA+B.
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