AD Leonis

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AD Leonis
Observation data
Epoch J2000      Equinox J2000
Constellation Leo
Right ascension 10h 19m 36.277s[1]
Declination +19° 52′ 12.06″[1]
Apparent magnitude (V) 9.32[2]
Characteristics
Spectral type M3.5eV[3]
U−B color index +1.06[2]
B−V color index +1.54[2]
Variable type Flare star[4]
Astrometry
Radial velocity (Rv) +10.8[5] km/s
Proper motion (μ) RA: –501.8[1] mas/yr
Dec.: –42.8[1] mas/yr
Parallax (π) 204.60 ± 2.80[6] mas
Distance 15.9 ± 0.2 ly
(4.89 ± 0.07 pc)
Absolute magnitude (MV) 10.87[6]
Details
Mass 0.39–0.42[6][7] M
Radius 0.39[7] R
Luminosity 0.024[8] L
Surface gravity (log g) 4.79[8] cgs
Temperature 3,390 ± 19[9] K
Metallicity [Fe/H] +0.28 ± 0.17[9] dex
Rotational velocity (v sin i) 3[7][10] km/s
Age 25-300[11] Myr
Other designations
Gliese 388, BD+20 2465, G 54-23, LHS 5167, LTT 12761, NLTT 24015, SAO 81292.[12]

AD Leonis (Gliese 388) is a red dwarf star. It is located relatively near the Sun, at a distance of about 16 light years, in the constellation Leo. AD Leonis is a main sequence star with a spectral classification of M3.5V.[3] It is a flare star that undergoes random increases in luminosity.[4][12]

Properties[edit]

AD Leonis is an M-type star with a spectral type M3.5eV, indicating it is a main sequence star that displays emission lines in its spectrum. At a trigonometric distance of 15.9 ly (4.9 pc), it has an apparent visual magnitude of 9.43.[6][8] It has about 39–42% of the Sun's mass—above the mass at which a star is fully convective[13]—and 39% of the Sun's radius.[6][7] The projected rotation of this star is only 3 km/s,[10] but it completes a rotation once every 2.24 days.[13] It is a relatively young star with an estimated age of 25–300 million years,[11] and is considered a member of the young disk population.[14]

The variable nature of this star was first observed in 1949 by Katherine C. Gordon and Gerald E. Kron at Lick Observatory.[15] AD Leonis is one of the most active flare stars known, and the emissions from the flares have been detected across the electromagnetic spectrum as high as the X-ray band.[16][17] The net magnetic flux at the surface is about 3 kG.[10] Besides star spots, about 73% of the surface is covered by magnetically active regions.[18] Examination of the corona in X-ray shows compact loop structures that span up to 30% of the size of the star.[19]

During a 1943 proper motion study by Dirk Reuyl at McCormick Observatory, it was suspected of having a companion. However, a 1968 study by Sarah L. Lippincott at Sproul Observatory was unable to confirm this result.[20] A 1997 search with a near-infrared speckle interferometer failed to detect a companion orbiting 1–10 AU from the star.[21] In 2001, an optical coronagraph was used to example the star, but no companion was found.[22] There is no sign of variability in its radial velocity, which would otherwise indicate the presence of an unseen companion.[8]

This star is orbiting through the Milky Way galaxy with an eccentricity of 0.028. This carries the star as close as 8.442 kpc from the galactic core, and as far as 8.926 kpc. The orbital inclination carries it as far as 0.121 kpc from the plane of the galaxy.[23]

See also[edit]

References[edit]

  1. ^ a b c d 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. 
  2. ^ a b c Nicolet, B. (October 1978). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics, Supplemental Series 34: 1–49. Bibcode:1978A&AS...34....1N. 
  3. ^ a b Shkolnik, Evgenya; Liu, Michael C.; Reid, I. Neill (July 2009). "Identifying the Young Low-mass Stars within 25 pc. I. Spectroscopic Observations". The Astrophysical Journal 699 (1): 649–666. arXiv:0904.3323. Bibcode:2009ApJ...699..649S. doi:10.1088/0004-637X/699/1/649. 
  4. ^ a b Kukarkin, B. V. et al. (1971). "The third edition containing information on 20437 variable stars discovered and designated till 1968". General Catalogue of Variable Stars (3rd ed.). Bibcode:1971GCVS3.C......0K. 
  5. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick. Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E. 
  6. ^ a b c d e "The One Hundred Nearest Star Systems". Research Consortium on Nearby Stars. Georgia State University. January 1, 2009. Retrieved 2009-09-25. 
  7. ^ a b c d Reiners, A.; Basri, G.; Browning, M. (February 2009). "Evidence for Magnetic Flux Saturation in Rapidly Rotating M Stars". The Astrophysical Journal 692 (1): 538–545. arXiv:0810.5139. Bibcode:2009ApJ...692..538R. doi:10.1088/0004-637X/692/1/538. 
  8. ^ a b c d Pettersen, B. R.; Coleman, L. A. (December 1981). "Chromospheric lines in red dwarf flare stars. I - AD Leonis and GX Andromedae". Astrophysical Journal 251 (12): 571–82. Bibcode:1981ApJ...251..571P. doi:10.1086/159500. 
  9. ^ a b Rojas-Ayala, Bárbara et al. (April 2012). "Metallicity and Temperature Indicators in M Dwarf K-band Spectra: Testing New and Updated Calibrations with Observations of 133 Solar Neighborhood M Dwarfs". The Astrophysical Journal 748 (2): 93. arXiv:1112.4567. Bibcode:2012ApJ...748...93R. doi:10.1088/0004-637X/748/2/93. 
  10. ^ a b c Reiners, A. (May 2007). "The narrowest M-dwarf line profiles and the rotation-activity connection at very slow rotation". Astronomy and Astrophysics 467 (1): 259–268. arXiv:astro-ph/0702634. Bibcode:2007A&A...467..259R. doi:10.1051/0004-6361:20066991. 
  11. ^ a b Shkolnik, Evgenya; Liu, Michael C.; Reid, I. Neill (July 2009), "Identifying the Young Low-mass Stars within 25 pc. I. Spectroscopic Observations", The Astrophysical Journal 699 (1): 649–666, arXiv:0904.3323, Bibcode:2009ApJ...699..649S, doi:10.1088/0004-637X/699/1/649. 
  12. ^ a b "V* AD Leo – Flare Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-09-25. 
  13. ^ a b Reiners, A.; Basri, G. (March 2009). "On the magnetic topology of partially and fully convective stars". Astronomy and Astrophysics 496 (3): 787–790. arXiv:0901.1659. Bibcode:2009A&A...496..787R. doi:10.1051/0004-6361:200811450. 
  14. ^ Sciortino, S.; Maggio, A.; Favata, F.; Orlando, S. (February 1999). "X-ray spectroscopy of the active dM stars: AD Leo and EV Lac". Astronomy & Astrophysics 342 (2): 502–14. Bibcode:1999A&A...342..502S. 
  15. ^ Gordon, Katherine C.; Kron, Gerald E. (October 1949), "Flare of a dMe Star, BD+20°2465, Observed Photoelectrically", Publications of the Astronomical Society of the Pacific 61 (362): 210–214, Bibcode:1949PASP...61..210G, doi:10.1086/126179. 
  16. ^ Osten, Rachel A.; Bastian, T. S. (February 2008). "Ultrahigh Time Resolution Observations of Radio Bursts on AD Leonis". The Astrophysical Journal 674 (2): 1078–1085. arXiv:0710.5881. Bibcode:2008ApJ...674.1078O. doi:10.1086/525013. 
  17. ^ Schmitt, J. H. M. M.; Fleming, T. A.; Giampapa, M. S. (September 1995). "The X-ray view of the low-mass stars in the solar neighborhood". Astrophysical Journal 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149. 
  18. ^ Crespo-Chacón, I. et al. (June 2006). "Analysis and modeling of high temporal resolution spectroscopic observations of flares on AD Leonis". Astronomy and Astrophysics 452 (3): 987–1000. arXiv:astro-ph/0602123. Bibcode:2006A&A...452..987C. doi:10.1051/0004-6361:20053615. 
  19. ^ Christian, D. J. et al. (August 2006), "Opacity in the upper atmospheres of active stars. II. AD Leonis", Astronomy and Astrophysics 454 (3): 889–894, arXiv:astro-ph/0602447, Bibcode:2006A&A...454..889C, doi:10.1051/0004-6361:20054404. 
  20. ^ Lippincott, S. L. (March 1969), "Astrometric study of BD +20 2465 from photographs taken with the Sproul 24-inch refractor", Astronomical Journal 74: 224–228, Bibcode:1969AJ.....74..224L, doi:10.1086/110795. 
  21. ^ Leinert, C. et al. (September 1997). "A search for companions to nearby southern M dwarfs with near-infrared speckle interferometry". Astronomy and Astrophysics 325: 159–166. Bibcode:1997A&A...325..159L. 
  22. ^ Oppenheimer, B. R. et al. (April 2001). "A Coronagraphic Survey for Companions of Stars within 8 Parsecs". The Astronomical Journal 121 (4): 2189–2211. arXiv:astro-ph/0101320. Bibcode:2001AJ....121.2189O. doi:10.1086/319941. 
  23. ^ Allen, C.; Herrera, M. A. (April 1998). "The Galactic Orbits of Nearby UV Ceti Stars". Revista Mexicana de Astronomía y Astrofísica 34: 37–46. Bibcode:1998RMxAA..34...37A.