Epsilon Leporis

Epsilon Leporis, Latinized from ε Leporis, is a third-magnitude star in the southern constellation Lepus. The apparent visual magnitude of +3.166[2] places it third in brightness among the stars in this constellation. Based upon parallax measurements, it is located at a distance of around 213 light-years (65 parsecs) from Earth.[1]

ε Leporis
Location of ε Leporis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lepus
Right ascension  05h 05m 27.66537s[1]
Declination –22° 22′ 15.7239″[1]
Apparent magnitude (V) +3.166[2]
Characteristics
Spectral type K4 III[3]
U−B color index +1.783[2]
B−V color index +1.478[2]
Astrometry
Radial velocity (Rv)+1.0[4] km/s
Proper motion (μ) RA: +21.13[1] mas/yr
Dec.: –73.11[1] mas/yr
Parallax (π)15.29 ± 0.19[1] mas
Distance213 ± 3 ly
(65.4 ± 0.8 pc)
Absolute magnitude (MV)–1.02 ± 0.10[5]
Details[5]
Mass1.70±0.19 M☉
Radius40.1±3.2 R☉
Luminosity372[6] L☉
Surface gravity (log g)1.43±0.09 cgs
Temperature4,131 K
Metallicity [Fe/H]–0.02 dex
Age1.72±0.47 Gyr
Other designations
ε Lep, 2 Leporis, NSV 1826, BD−22° 1000, FK5 186, HD 32887, HIP 23685, HR 1654, SAO 170051[7]
Database references
SIMBADdata

This is an evolved giant star with a stellar classification of K4 III[3] that has expanded to 40 times the Sun's radius. It is about 1.72 billion years old and has 1.70 times the mass of the Sun, with a luminosity 372[6] times as great. The outer atmosphere is cooler than the Sun's with an effective temperature of 4,131 K,[5] giving it the orange hue of a K-type star.[8] In terms of its composition, this star shows a similar abundance of elements other than hydrogen and helium to the Sun.[5]

The envelope of this star is undergoing oscillations that show up as changes in the star's radial velocity. Over long durations these follow a linear trend, in combination with shorter period oscillations occurring over a few days. These oscillations are unlikely to be the result of rotational module as that would imply a high rotation rate, which would display itself through strong X-ray emissions. Instead, they may be the result of solar-like and Mira-like oscillations.[9]

References
  1. van Leeuwen, F. (November 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.
  2. Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G
  3. Houk, Nancy; Smith-Moore, M. (1978), "Michigan catalogue of two-dimensional spectral types for the HD stars", Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, Ann Arbor: Dept. of Astronomy, University of Michigan, 4, Bibcode:1988mcts.book.....H.
  4. Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg, Astronomisches Rechen-Institut Heidelberg, 35 (35): 1, Bibcode:1999VeARI..35....1W
  5. da Silva, L.; et al. (November 2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics, 458 (2): 609–623, arXiv:astro-ph/0608160, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105.
  6. di Mauro, M. P.; Cardini, D. (October 2006), "Asteroseismology of K giants", in Fletcher, Karen; Thompson, Michael (eds.), Proceedings of SOHO 18/GONG 2006/HELAS I, Beyond the spherical Sun (ESA SP-624), 624, Sheffield, UK, p. 118, Bibcode:2006ESASP.624E.118D
  7. "eps Lep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-10-29.
  8. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-18, retrieved 2012-01-16
  9. Setiawan, J.; et al. (2006), "Multi-periodic oscillations of HD 32887 and HD 81797", Memorie della Società Astronomica Italiana, 77: 510, arXiv:astro-ph/0505184, Bibcode:2006MmSAI..77..510S
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