Astronomy:HD 44780
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Gemini[1] |
| Right ascension | 06h 24m 43.74735s[2] |
| Declination | +25° 02′ 55.3981″[2] |
| Apparent magnitude (V) | 6.35[3] |
| Characteristics | |
| Spectral type | K2 III[4] (K2–K3 + K0–K1)[5] |
| B−V color index | +1.210±0.015[3] |
| Astrometry | |
| Radial velocity (Rv) | +17.2±0.3[3] km/s |
| Proper motion (μ) | RA: +2.459[2] mas/yr Dec.: −1.895[2] mas/yr |
| Parallax (π) | 3.4049 ± 0.1139[2] mas |
| Distance | 960 ± 30 ly (294 ± 10 pc) |
| Absolute magnitude (MV) | −0.53[3] |
| Orbit[1] | |
| Period (P) | 577.5±0.5 d |
| Semi-major axis (a) | 4.16±1.28 mas[5] |
| Eccentricity (e) | 0.240±0.006 |
| Inclination (i) | 109±12[5]° |
| Periastron epoch (T) | 43,625.5±2.8 MJD |
| Argument of periastron (ω) (secondary) | 85.8±1.9° |
| Semi-amplitude (K1) (primary) | 22.06±0.15 km/s |
| Semi-amplitude (K2) (secondary) | 22.66±0.32 km/s |
| Details | |
| A | |
| Mass | 3.10±0.65[5] M☉ |
| Luminosity | 248.32[3] L☉ |
| Age | 400[5] Myr |
| B | |
| Mass | 3.02±0.64[5] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 44780 is a binary star system in the northern constellation of Gemini, located about 3° north of Mu Geminorum.[1][7] The pair have a combined apparent visual magnitude of 6.35,[3] which is near the lower limit of visibility to the naked eye. Although it is above magnitude 6.5, it was not included in the Bright Star Catalogue;[1] the designation HD 44780 comes from the Henry Draper catalogue. Based upon parallax measurements, the system is located at a distance of approximately 960 light years from the Sun. It is drifting further away with a radial velocity of +17 km/s.[3]
The variable velocity of this system was first noted during a study at Mount Wilson observatory in 1952.[1] It is a double-lined spectroscopic binary[5] system with an orbital period of 1.581 years and an eccentricity of 0.24. Both components are similar, aging giant stars, a relatively rare combination.[1] Their combined spectrum matches a stellar classification of K2 III;[4] with the secondary being a slightly earlier type than the primary. They have an age of about 400 million years, with masses 3.10 and 3.02 times that of the Sun.[5]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Griffin, R. F. (April 1986), "The spectroscopic orbits of HD 44780 and 65 Geminorum", Journal of the Royal Astronomical Society of Canada 80: 91–108, Bibcode: 1986JRASC..80...91G.
- ↑ 2.0 2.1 2.2 2.3 2.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 4.0 4.1 Heard, John Frederick (1956), "The radial velocities, spectral classes and photographic magnitudes of 1041 late-type stars", Publications of the David Dunlap Observatory (University of Toronto, Toronto, Canada: University of Toronto Press) 2 (4): 107–143, Bibcode: 1956PDDO....2..107H.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Pourbaix, D.; Boffin, H. M. J. (February 2003), "Reprocessing the Hipparcos Intermediate Astrometric Data of spectroscopic binaries. II. Systems with a giant component", Astronomy and Astrophysics 398 (3): 1163–1177, doi:10.1051/0004-6361:20021736, Bibcode: 2003A&A...398.1163P.
- ↑ "HD 44780". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+44780.
- ↑ HD 044780, VizieR, http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HD%2044780, retrieved 2011-11-30.
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