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HR 8442 
Summary
HR 8442 is a spectroscopic binary star in the constellation Cepheus. The primary is a G type giant star while the secondary's spectral type is unknown.[4]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 07m 09.634s[1] |
| Declination | +58° 50′ 26.58″[1] |
| Apparent magnitude (V) | 6.32[2] |
| Characteristics | |
| Spectral type | G8.6 III[3] |
| U−B color index | 0.63[2] |
| B−V color index | 0.88[2] |
| Astrometry | |
| Radial velocity (Rv) | −7.37±0.03[4] km/s |
| Proper motion (μ) | RA: −16.09±0.41[1] mas/yr Dec.: −22.30±0.41[1] mas/yr |
| Parallax (π) | 4.80 ± 0.46 mas[1] |
| Distance | 680 ± 70 ly (210 ± 20 pc) |
| Absolute magnitude (MV) | −0.3±0.2[4] |
| Orbit[4] | |
| Primary | HR 8442A |
| Companion | HR 8442B |
| Period (P) | 737.4±0.4 days |
| Eccentricity (e) | 0.308±0.007 |
| Periastron epoch (T) | 54113.3±2.1 |
| Argument of periastron (ω) (secondary) | 61.9±1.3° |
| Semi-amplitude (K1) (primary) | 5.55±0.04 km/s |
| Details | |
| Mass | 2.97[5] M☉ |
| Temperature | 5261±40[5] K |
| Age | 0.35[5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectroscopic binary nature of the star was first noticed by Jose Renan de Medeiros and Michel Mayor using radial velocity measurements from the Coravel spectrometer at Haute-Provence Observatory.[6] Roger Griffin then placed the star on his observing program at Cambridge Observatory leading to an orbital solution being published in 2015.[4]
References edit
- ^ a b c d e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry
- ^ a b c Argue, A. N. (1966). "UBV photometry of 550 F, G and K type stars". Monthly Notices of the Royal Astronomical Society. 133 (4): 175–493. Bibcode:1966MNRAS.133..475A. doi:10.1093/mnras/133.4.475.
- ^ Gray, David F. (1989). "The rotational break for G giants". Astrophysical Journal. 347: 1021–1029. Bibcode:1989ApJ...347.1021G. doi:10.1086/168192.
- ^ a b c d e Griffin, R. F. (2015). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 241: HR 1884, HD 174103, HD 182563, and HR 8442, with a note on zeta Cephei". The Observatory. 135: 71–95. Bibcode:2015Obs...135...71G.
- ^ a b c Luck, R. Earle (2015). "Abundances in the Local Region. I. G and K Giants". Astronomical Journal. 150 (3). 88. arXiv:1507.01466. Bibcode:2015AJ....150...88L. doi:10.1088/0004-6256/150/3/88. S2CID 118505114.
- ^ de Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement. 139 (3): 433–460. arXiv:astro-ph/0608248. Bibcode:1999A&AS..139..433D. doi:10.1051/aas:1999401.