AK Leporis

AK Leporis is a star in the southern constellation of Lepus the hare. It has an apparent visual magnitude of 6.141,[2] so, according to the Bortle scale, it is faintly visible from rural skies at night. This star forms a visual double with Gamma Leporis—the two have an angular separation of 97″, making them difficult to separate with the naked eye even under the best conditions.[11] Both Gamma Leporis and AK Leporis are members of the Ursa Major Moving Group of stars that share a common motion through space.[5]

AK Leporis
Observation data
Epoch J2000      Equinox J2000
Constellation Lepus
Right ascension 05h 44m 26.543s[1]
Declination −22° 25′ 18.77″[1]
Apparent magnitude (V) 6.141[2]
Characteristics
Spectral type K2V[3]
U−B color index +0.74[4]
B−V color index +0.96[4]
Variable type BY Draconis[3]
Astrometry
Radial velocity (Rv)−9.57 ± 0.13[5] km/s
Proper motion (μ) RA: −304.4[6] mas/yr
Dec.: −352.2[6] mas/yr
Parallax (π)112.0[7] mas
Distance28 ly
(9.0[8] pc)
Absolute magnitude (MV)6.31[2]
Details
Surface gravity (log g)4.66 ± 0.01[9] cgs
Temperature4,869 ± 61[9] K
Metallicity [Fe/H]0.01 ± 0.06[9] dex
Rotational velocity (v sin i)2.8 ± 1.8[5] km/s
Age0.9[8] Gyr
Other designations
BD−22 1210, GJ 216 B, HD 38392, HR 1982, LTT 2363, SAO 170757.[10]
Database references
SIMBADdata

This is a BY Draconis variable star that undergoes brightness variations due to stellar activity. Differential rotation causes changes to the periodicity of the variation depending on the latitude of the activity.[3] X-ray emission has been detected from AK Leporis, and it is located at or near a radio source.[7]

Infrared observation of this star shows a large excess at a wavelength of 24 µm. This may be explained by the proximity of Gamma Leporis to the line of sight, or there may be a red dwarf companion or a dust disc. There is no excess observed at 70 µm.[8]

References
  1. Roeser, S.; Bastian, U. (September 1988), "A new star catalogue of SAO type", Astronomy and Astrophysics Supplement Series, 74 (3): 449–451, Bibcode:1988A&AS...74..449R.
  2. Nordström, Andersen; et al. (2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14000 F and G dwarfs", Publications of the Astronomical Society of Australia, 21 (2): 129–133, Bibcode:2004PASA...21..129N, doi:10.1071/AS04013.
  3. Lecavelier Des Etangs, A.; et al. (August 2005), "A photometric survey of stars with circumstellar material", Astronomy and Astrophysics, 439 (2): 571–574, Bibcode:2005A&A...439..571L, doi:10.1051/0004-6361:20042401.
  4. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  5. Biazzo, K.; et al. (December 2012), "Elemental abundances of low-mass stars in nearby young associations: AB Doradus, Carina Near and Ursa Major", Monthly Notices of the Royal Astronomical Society, 427 (4): 2905–2916, arXiv:1209.2591, Bibcode:2012MNRAS.427.2905B, doi:10.1111/j.1365-2966.2012.22132.x, S2CID 118617986.
  6. Høg, E.; et al. (March 2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27–L30, Bibcode:2000A&A...355L..27H, doi:10.1888/0333750888/2862.
  7. Lazio, T. Joseph W.; et al. (January 2010), "A Blind Search for Magnetospheric Emissions from Planetary Companions to Nearby Solar-Type Stars", The Astronomical Journal, 139 (1): 96–101, arXiv:0910.3938, Bibcode:2010AJ....139...96L, doi:10.1088/0004-6256/139/1/96, S2CID 118537554.
  8. Lawler, S. M.; et al. (November 2009), "Explorations Beyond the Snow Line: Spitzer/IRS Spectra of Debris Disks Around Solar-type Stars", The Astrophysical Journal, 705 (1): 89–111, arXiv:0909.0058, Bibcode:2009ApJ...705...89L, doi:10.1088/0004-637X/705/1/89, S2CID 1272803.
  9. Prugniel, Ph.; et al. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769, S2CID 54940439.
  10. "V* AK Lep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-04-02.
  11. Kaler, James B., "Gamma Leporis", Stars, University of Illinois, retrieved 2015-04-02.
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