Pi Eridani

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.

π Eridani
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
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 mas[1]
Distance480 ± 40 ly
(150 ± 10 pc)
Absolute magnitude (MV)−1.40[7]
Details
Radius77[8] R☉
Luminosity1,123[9] L☉
Temperature3,841[9] K
Other designations
π Eridani, π Eri, 26 Eridani, BD-12° 707, HD 23614, HIP 17593, HR 1162, SAO 149158.[10]
Database references
SIMBADdata

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. 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.
  2. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.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. Samus, N. N.; Durlevich, O. V.; et al. (2007), Combined General Catalogue of Variable Stars (GCVS4.2), retrieved 2016-09-30. VizieR On-line Data Catalog: B/gcvs. {{citation}}: External link in |postscript= (help)CS1 maint: postscript (link)
  4. Eggen, O. J. (1992), "Asymptotic giant branch stars near the sun", The Astronomical Journal, 104: 275, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
  5. Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, vol. 4, Bibcode:1988mcts.book.....H.
  6. 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, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  7. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  8. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3 ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
  9. 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.
  10. "* pi. Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-11.{{cite web}}: CS1 maint: postscript (link)
  11. Mennessier, M. O.; et al. (August 2001), "Long period variable stars: galactic populations and infrared luminosity calibrations", Astronomy and Astrophysics, 374 (3): 968–979, arXiv:astro-ph/0105552, Bibcode:2001A&A...374..968M, doi:10.1051/0004-6361:20010764, S2CID 15721872.
  12. Richichi, A.; Percheron, I. (May 2005), "First results from the ESO VLTI calibrators program", Astronomy and Astrophysics, 434 (3): 1201–1209, arXiv:astro-ph/0501532, Bibcode:2005A&A...434.1201R, doi:10.1051/0004-6361:20042257, S2CID 2847613.
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