66 Eridani is a binary star in the constellation of Eridanus. The combined apparent magnitude of the system is 5.12 on average.[2] Parallax measurements by Hipparcos put the system at some 309 light-years (95 parsecs) away.[1]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 05h 06m 45.65314s[1] |
| Declination | −04° 39′ 18.5939″[1] |
| Apparent magnitude (V) | 5.12[2] |
| Characteristics | |
| Spectral type | B9V[3] |
| U−B color index | -0.16[4] |
| B−V color index | -0.06[4] |
| Variable type | α2 CVn |
| Astrometry | |
| Radial velocity (Rv) | 32.28 ± 0.10[5] km/s |
| Proper motion (μ) | RA: 10.70[1] mas/yr Dec.: -0.78[1] mas/yr |
| Parallax (π) | 10.56 ± 0.34 mas[1] |
| Distance | 309 ± 10 ly (95 ± 3 pc) |
| Absolute magnitude (MV) | 0.37[6] |
| Orbit[5] | |
| Period (P) | 5.5226013 ± 0.0000020 d |
| Eccentricity (e) | 0.0844 ± 0.0013 |
| Periastron epoch (T) | 2441356.499 ± 0.017 |
| Argument of periastron (ω) (secondary) | 160.9 ± 1.1° |
| Semi-amplitude (K1) (primary) | 102.83 ± 0.20 km/s |
| Semi-amplitude (K2) (secondary) | 100.35 ± 0.19 km/s |
| Details[5] | |
| 66 Eri A | |
| Mass | 2.629 ± 0.032 M☉ |
| Radius | 1.948 ± 0.063 R☉ |
| Luminosity | 51.3 ± 3.3 L☉ |
| Surface gravity (log g) | 4.28 ± 0.03 cgs |
| Temperature | 11077 K |
| Rotational velocity (v sin i) | 17.1 ± 0.2 km/s |
| Age | 30 Myr |
| 66 Eri B | |
| Mass | 2.566 ± 0.032 M☉ |
| Radius | 1.919 ± 0.061 R☉ |
| Luminosity | 46.9 ± 3.0 L☉ |
| Surface gravity (log g) | 4.28 ± 0.03 cgs |
| Temperature | 10914 K |
| Rotational velocity (v sin i) | 16.9 ± 0.2 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a spectroscopic binary: the two stars cannot be individually resolved, but periodic Doppler shifts in its spectrum mean there must be orbital motion. The two stars orbit each other every 5.5226013 days.[5] Their orbit is fairly eccentric, at 0.0844.[5]
The combined spectrum of 66 Eridani matches that of a B-type main-sequence star,[3] and the two stars have similar masses.[5] The spectrum also shows excess of mercury and manganese, as it is a type of chemically peculiar star called a mercury-manganese star.[5] 66 Eridani is an Alpha2 Canum Venaticorum variable. For this reason, it has been given the designation EN Eridani.[7]
References
edit- ^ a b c d e f van Leeuwen, F.; et al. (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.
- ^ a b Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
- ^ a b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 5: 0. Bibcode:1999MSS...C05....0H.
- ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ a b c d e f g Makaganiuk, V.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. (2011). "Chemical spots in the absence of magnetic field in the binary Hg Mn star 66 Eridani". Astronomy & Astrophysics. 529: A160. arXiv:1102.4661. Bibcode:2011A&A...529A.160M. doi:10.1051/0004-6361/201016302. S2CID 118419097.
- ^ Hubrig, S.; et al. (June 2001), "Search for low-mass PMS companions around X-ray selected late B stars", Astronomy and Astrophysics, 372: 152–164, arXiv:astro-ph/0103201, Bibcode:2001A&A...372..152H, doi:10.1051/0004-6361:20010452, S2CID 17507782.
- ^ a b "* 66 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 13 August 2017.