54 Eridani

54 Eridani is a suspected astrometric binary[9] star system located around 400 light years from the Sun in the equatorial constellation of Eridanus. It is visible to the naked eye as a faint, reddish hued star with a baseline apparent visual magnitude of 4.32.[2] The object is moving closer to the Earth with a heliocentric radial velocity of −33 km/s.[2]

54 Eridani
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Eridanus
Right ascension 04h 40m 26.51159s[1]
Declination −19° 40′ 17.3723″[1]
Apparent magnitude (V) 4.32[2]
Characteristics
Evolutionary stage asymptotic giant branch[3]
Spectral type M3/4 III[4]
U−B color index +1.80[5]
B−V color index 1.599±0.021[2]
Variable type SRb[6]
Astrometry
Radial velocity (Rv)−32.9±0.8[2] km/s
Proper motion (μ) RA: +29.13[7] mas/yr
Dec.: −96.42[7] mas/yr
Parallax (π)8.2063 ± 0.2709[1] mas
Distance400 ± 10 ly
(122 ± 4 pc)
Absolute magnitude (MV)−0.93[2]
Details
Radius69+12
−6[1] R☉
Luminosity1,021+33
−38[1] L☉
Temperature3,915+190
−293[1] K
Other designations
DM Eridani, BD−19°988, GC 5695, HD 29755, HIP 21763, HR 1496, SAO 149818, WDS J04404-1940[8]
Database references
SIMBADdata

The visible component is an aging red giant star, currently on the asymptotic giant branch,[3] with a stellar classification of M3/4 III.[4] It is a semiregular variable star of subtype SRb, ranging in magnitude from 4.28 down to 4.36.[6] The star has pulsation periods of 18.8 and 45.5 days, each with an amplitude of 0.019 in magnitude.[10] With the hydrogen at its core exhausted, the star has expanded to around 69[1] times the Sun's radius and it is radiating 1,021[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,915 K.[1]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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.
  3. Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal, 104 (1): 275–313, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
  4. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  5. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  7. 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.
  8. "54 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-28.
  9. 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  10. 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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