Location of τ4 Eridani (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03 19 31.0006 |
| Declination | −21° 45′ 28.315″ |
| Apparent magnitude (V) | 3.65 |
| Characteristics | |
| Evolutionary stage | asymptotic giant branch |
| Spectral type | M3/4 III |
| U−B color index | +1.79 |
| B−V color index | +1.61 |
| Variable type | Lb |
| Astrometry | |
| Radial velocity (Rv) | +41.7±0.7 km/s |
| Proper motion (μ) | RA: +52.774 mas/yr Dec.: +32.718 mas/yr |
| Parallax (π) | 10.6153 ± 0.3213 mas |
| Distance | 307 ± 9 ly (94 ± 3 pc) |
| Absolute magnitude (MV) | −0.79 |
| Details | |
| Mass | 1.73±0.3 M☉ |
| Radius | 103 R☉ |
| Luminosity | 1,537 L☉ |
| Surface gravity (log g) | 0.91 cgs |
| Temperature | 3,652 K |
| Other designations | |
| τ Eridani, τ Eri, 16 Eridani, BD-22° 584, HD 20720, HIP 15474, HR 1003, SAO 168460. | |
| Database references | |
| SIMBAD | data |
Tau Eridani (τ Eridani, τ Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.65. The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years.
This is an evolved red giant star currently on the asymptotic giant branch with a stellar classification of M3/4 III. It is a slow irregular variable star of type Lb, undergoing changes in magnitude over the range 3.57−3.72 with a periodicity of 23.8 d. The measured angular diameter of Tau Eridani is 10.58±1.00 mas. At its estimated distance, this yields a physical size of about 106 times the radius of the Sun. It shines with 1,537 times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,650 K.
This is most likely a binary star system. The companion is a magnitude 9.5 star at an angular separation of 5.7″ along a position angle of 291°, as of 2013.
References
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- ^ Wood, Brian E.; Müller, Hans-Reinhard; Harper, Graham M. (2016-09-23), "Hubble Space Telescope Constraints on the Winds and Astrospheres of Red Giant Stars", The Astrophysical Journal, 829 (2): 74, arXiv:1607.07732, Bibcode:2016ApJ...829...74W, doi:10.3847/0004-637X/829/2/74, ISSN 0004-637X
- ^ McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
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- "tau04 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-13.
{{cite web}}: CS1 maint: postscript (link) - ^ Tabur, V.; et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–1961, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x, S2CID 15358380.
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