| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 04 33 30.55236 |
| Declination | −29° 45′ 59.3725″ |
| Apparent magnitude (V) | 4.51 |
| Characteristics | |
| Spectral type | K0 III-IV |
| U−B color index | +0.70 |
| B−V color index | +0.98 |
| Astrometry | |
| Radial velocity (Rv) | +20.89±0.69 km/s |
| Proper motion (μ) | RA: −114.78 mas/yr Dec.: −271.79 mas/yr |
| Parallax (π) | 25.67 ± 0.24 mas |
| Distance | 127 ± 1 ly (39.0 ± 0.4 pc) |
| Absolute magnitude (MV) | 1.60 |
| Details | |
| Mass | 1.54 M☉ |
| Radius | 7.3 R☉ |
| Luminosity | 24 L☉ |
| Surface gravity (log g) | 3.09 cgs |
| Temperature | 4,941 K |
| Metallicity | −0.16±0.08 dex |
| Rotational velocity (v sin i) | 2.15 km/s |
| Other designations | |
| υ Eridani, υ Eri, 50 Eridani, CD−30° 1883, HD 29085, HIP 21248, HR 1453, SAO 169570. | |
| Database references | |
| SIMBAD | data |
Upsilon Eridani (υ Eri) is a single star in the constellation Eridanus. It has an apparent visual magnitude is 4.51, which is bright enough to be faintly visible to the naked eye on a clear, dark night. The distance to this star, as determined using the parallax method, is around 127 light years.
This is an evolved red clump giant star with a stellar classification of K0III-IV. The measured angular diameter, after correction for limb darkening, is 1.74±0.02 mas. At an estimated distance of this star, this yields a physical size of about 7.3 times the radius of the Sun. It has 154% of the Sun's mass and radiates 24 times the solar luminosity from its outer atmosphere at an effective temperature of 4,941 K.
References
- ^ 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.
- ^ Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
- ^ Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
- ^ Luck, R. Earle; Heiter, Ulrike (June 2007), "Giants in the Local Region", The Astronomical Journal, 133 (6): 2464–2486, Bibcode:2007AJ....133.2464L, doi:10.1086/513194.
- ^ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
- Hekker, S.; Meléndez, J. (2007). "Precise radial velocities of giant stars. III. Spectroscopic stellar parameters". Astronomy and Astrophysics. 475 (3): 1003. arXiv:0709.1145. Bibcode:2007A&A...475.1003H. doi:10.1051/0004-6361:20078233. S2CID 10436552.
- "* ups01 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-13.
{{cite web}}: CS1 maint: postscript (link) - Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278, S2CID 16673121.
- Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
