Astronomy:Phi Eridani
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 02h 16m 30.58563s[1] |
| Declination | −51° 30′ 43.7955″[1] |
| Apparent magnitude (V) | 3.55[2] |
| Characteristics | |
| Spectral type | B8IV-V[3] |
| U−B color index | −0.38[2] |
| B−V color index | −0.12[2] |
| Astrometry | |
| Radial velocity (Rv) | 10.40[4] km/s |
| Proper motion (μ) | RA: +91.03[1] mas/yr Dec.: −22.23[1] mas/yr |
| Parallax (π) | 21.22 ± 0.12[1] mas |
| Distance | 153.7 ± 0.9 ly (47.1 ± 0.3 pc) |
| Absolute magnitude (MV) | 0.183±0.027[5] |
| Details | |
| Mass | 3.55[6] M☉ |
| Radius | 3.4[7] R☉ |
| Luminosity | 255[8] L☉ |
| Surface gravity (log g) | 4.21±0.14[6] cgs |
| Temperature | 13,716±466[6] K |
| Rotation | 0.343705[9] d |
| Rotational velocity (v sin i) | 250[10] km/s |
| Age | 44[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
φ Eridani (Latinised as Phi Eridani) is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.55.[2] The distance to this star, as determined using the parallax method, is around 154 light-years.[1]
This is a B-type star with a stellar classification of B8IV-V,[3] suggesting it shows traits of a main-sequence star and a subgiant. It is spinning rapidly with a projected rotational velocity of 250 km/s. This rotation is giving the star an oblate shape with an equator that is 17% larger than the polar radius. The estimated angular size is 0.68 milliarcseconds.[10] Since the distance is known, this yields a physical size of around 3.4 times the radius of the Sun.[7] It has 3.55 times the mass of the Sun and radiates 255 times the solar luminosity from its outer atmosphere at an effective temperature of about 13,716 K.[6]
Phi Eridani may form a wide binary star system with a 9th-magnitude star at lies an angular separation of 86″. This companion is a G-type main-sequence star with a stellar classification of G2V.[12] It may also have a physical association with the naked-eye star Eta Horologii.[13] It is a member of the Tucana-Horologium association, a 45(±4)-Myr-old group of stars that share a common motion through space.[5]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.
- ↑ 3.0 3.1 Zuckerman, B.; Song, Inseok (2004), "Young Stars Near the Sun", Annual Review of Astronomy & Astrophysics 42 (1): 685–721, doi:10.1146/annurev.astro.42.053102.134111, Bibcode: 2004ARA&A..42..685Z.
- ↑ De Bruijne, J. H. J.; Eilers, A.-C. (2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics 546: A61, doi:10.1051/0004-6361/201219219, Bibcode: 2012A&A...546A..61D.
- ↑ 5.0 5.1 Bell, Cameron P. M. et al. (November 2015), "A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood", Monthly Notices of the Royal Astronomical Society 454 (1): 593–614, doi:10.1093/mnras/stv1981, Bibcode: 2015MNRAS.454..593B.
- ↑ 6.0 6.1 6.2 6.3 6.4 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal 804 (2): 146, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D.
- ↑ 7.0 7.1 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1, https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41. The radius (R*) is given by:
- [math]\displaystyle{ \begin{align} 2\cdot R_* & = \frac{(47.1\cdot 0.68\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 6.88\cdot R_{\bigodot} \end{align} }[/math]
- ↑ McDonald, I. et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–57, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M.
- ↑ Barraza, L. F.; Gomes, R. L.; Messias, Y. S.; Leão, I. C.; Almeida, L. A.; Janot-Pacheco, E.; Brito, A. C.; Brito, F. A. C. et al. (2022). "Rotation Signature of TESS B-type Stars. A Comprehensive Analysis". The Astrophysical Journal 924 (2): 117. doi:10.3847/1538-4357/ac3335. Bibcode: 2022ApJ...924..117B.
- ↑ 10.0 10.1 van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review 20 (1): 51, doi:10.1007/s00159-012-0051-2, Bibcode: 2012A&ARv..20...51V.
- ↑ "phi Eri". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=phi+Eri.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ Shaya, Ed J.; Olling, Rob P. (January 2011), "Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue", The Astrophysical Journal Supplement 192 (1): 2, doi:10.1088/0067-0049/192/1/2, Bibcode: 2011ApJS..192....2S.
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