Epsilon Leporis

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Epsilon Leporis
Diagram showing star positions and boundaries of the Lepus constellation and its surroundings
Cercle rouge 100%.svg

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
Distance 213 ± 3 ly
(65.4 ± 0.8 pc)
Absolute magnitude (MV) –1.02 ± 0.10[5]
Details
Mass 1.70 ± 0.19[5] M
Radius 40.1 ± 3.2[5] R
Luminosity 372[6] L
Surface gravity (log g) 1.43 ± 0.09[5] cgs
Temperature 4,131[5] K
Metallicity [Fe/H] –0.02[5] dex
Age 1.72 ± 0.47[5] Gyr
Other designations
2 Leporis, BD-22 1000, FK5 186, HD 32887, HIP 23685, HR 1654, NSV 1826, SAO 170051.[7]

Epsilon Leporis (ε Lep, ε Lep) 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]

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[edit]

  1. ^ a b c d e f van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752free to read. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966). "A System of photometric standards". Publ. Dept. Astron. Univ. Chile. Publicaciones Universidad de Chile, Department de Astronomy. 1: 1–17. Bibcode:1966PDAUC...1....1G. 
  3. ^ a b 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. Volume 4, Ann Arbor: Dept. of Astronomy, University of Michigan, 4, Bibcode:1988MSS...C04....0H 
  4. ^ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb, Astronomisches Rechen-Institut Heidelberg, 35 (35): 1, Bibcode:1999VeARI..35....1W 
  5. ^ a b c d e f g h i 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/0608160free to read, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105 
  6. ^ a b di Mauro, M. P.; et al. (October 2006). "Asteroseismology of K giants". In Fletcher, Karen; Thompson, Michael. Proceedings of SOHO 18/GONG 2006/HELAS I, Beyond the spherical Sun (ESA SP-624). Proceedings of SOHO 18/GONG 2006/HELAS I. 624. Sheffield, UK. p. 118. Bibcode:2006ESASP.624E.118D. 
  7. ^ "HD 32887 -- Variable Star". SIMBAD Astronomical Object Database. 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, 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/0505184free to read, Bibcode:2006MmSAI..77..510S