Astronomy:Pi Eridani
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Short description: Red giant star in the constellation Eridanus
| Observation data Epoch J2000.0 Equinox (celestial coordinates) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03h 46m 08.53581s[1] |
| Declination | −12° 06′ 05.7282″[1] |
| Apparent magnitude (V) | 4.40[2] (4.38 - 4.44[3]) |
| Characteristics | |
| Evolutionary stage | asymptotic giant branch[4] |
| Spectral type | M1 III[5] |
| U−B color index | +1.96[2] |
| B−V color index | +1.61[2] |
| Variable type | Lb?[3] |
| Astrometry | |
| Radial velocity (Rv) | 45.2±0.1[6] km/s |
| Proper motion (μ) | RA: +55.98[1] mas/yr Dec.: +59.28[1] mas/yr |
| Parallax (π) | 6.78 ± 0.53[1] mas |
| Distance | 480 ± 40 ly (150 ± 10 pc) |
| Absolute magnitude (MV) | −1.40[7] |
| Details | |
| Radius | 77[8] R☉ |
| Luminosity | 1,123[9] L☉ |
| Temperature | 3,841[9] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
Pi Eridani, Latinized from π Eridani, is a star in the constellation Eridanus. It has an apparent visual magnitude of 4.40,[2] which is bright enough to be seen on a dark, clear night. Based upon parallax measurements, it is located roughly 480 light years from the Sun.
This is an evolved red giant star with a stellar classification of M1 III,[5] and is currently on the asymptotic giant branch.[4] It is a slow irregular variable type LB that can increase in magnitude up to 4.38.[3][11] The measured angular diameter of this star is 4.8±0.5 mas.[12] At the estimated distance of Pi Eridani, this yields a physical size of about 77 times the radius of the Sun.[8] It shines with 1,123[9] times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,841 K.[9]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 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- ↑ 2.0 2.1 2.2 2.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.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 3.2 Samus, N. N.; Durlevich, O. V. et al. (2007), Combined General Catalogue of Variable Stars (GCVS4.2), http://www.sai.msu.su/gcvs/gcvs/, retrieved 2016-09-30. VizieR On-line Data Catalog: B/gcvs.
- ↑ 4.0 4.1 Eggen, O. J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal 104: 275, doi:10.1086/116239, Bibcode: 1992AJ....104..275E.
- ↑ 5.0 5.1 Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Bibcode: 1988mcts.book.....H.
- ↑ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 8.0 8.1 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3 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{(150\cdot 4.8\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 155\cdot R_{\bigodot} \end{align} }[/math]
- ↑ 9.0 9.1 9.2 9.3 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.
- ↑ "* pi. Eri". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+pi.+Eri.
- ↑ Mennessier, M. O. et al. (August 2001), "Long period variable stars: galactic populations and infrared luminosity calibrations", Astronomy and Astrophysics 374 (3): 968–979, doi:10.1051/0004-6361:20010764, Bibcode: 2001A&A...374..968M.
- ↑ Richichi, A.; Percheron, I. (May 2005), "First results from the ESO VLTI calibrators program", Astronomy and Astrophysics 434 (3): 1201–1209, doi:10.1051/0004-6361:20042257, Bibcode: 2005A&A...434.1201R.
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