AD Leonis

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][13]

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)203.9 ± 2.8[6] mas
Distance16.0 ± 0.2 ly
(4.90 ± 0.07 pc)
Absolute magnitude (MV)10.87[7]
Details
Mass0.39–0.42[7][8] M☉
Radius0.39[8] R☉
Luminosity0.024[9] L☉
Surface gravity (log g)4.79[9] cgs
Temperature3,390 ± 19[10] K
Metallicity [Fe/H]+0.28 ± 0.17[10] dex
Rotational velocity (v sin i)3[8][11] km/s
Age25-300[12] Myr
Other designations
Gliese 388, BD+20 2465, G 54-23, LHS 5167, LTT 12761, NLTT 24015, SAO 81292, PLX 2420, TYC 1423-174-1[13]
Database references
SIMBADdata

Properties

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.[7][9] It has about 39–42% of the Sun's mass — above the mass at which a star is fully convective[14] — and 39% of the Sun's radius.[7][8] The projected rotation of this star is only 3 km/s,[11] but it completes a rotation once every 2.24 days.[14] It is a relatively young star with an estimated age of 25–300 million years,[12] and is considered a member of the young disk population.[15]

The variable nature of this star was first observed in 1949 by Katherine C. Gordon and Gerald E. Kron at Lick Observatory.[16] 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.[17][18] The net magnetic flux at the surface is about 3 kG.[11] Besides star spots, about 73% of the surface is covered by magnetically active regions.[19] Examination of the corona in X-ray shows compact loop structures that span up to 30% of the size of the star.[20] The average temperature of the corona is around 6.39 MK.[21]

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.[22] A 1997 search with a near-infrared speckle interferometer failed to detect a companion orbiting 1–10 AU from the star.[23] In 2001, an optical coronagraph was used to example the star, but no companion was found.[24] There is no sign of variability in its radial velocity, which would otherwise indicate the presence of an unseen companion.[9]

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.[25]

Planetary System

In 2019 one candidate planet been detected by the radial velocity method[26] but was refuted in 2020.[27]

The AD Leonis planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b (unconfirmed) 23.1+6.2
−5.6 M⊕		 0.025+0.002
−0.003		 2.22599+0.00087
−0.00042		 0.03+0.15
−0.03		 — —

See also
  • List of nearest stars

References
  1. Høg, E.; Fabricius, C.; Makarov, V.V.; Urban, S.; Corbin, T.; Wycoff, G.; 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.
  2. Nicolet, B. (October 1978). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics Supplement Series. 34: 1–49. Bibcode:1978A&AS...34....1N.
  3. 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. S2CID 118623086.
  4. Kukarkin, B.V.; Kholopov, P.N.; Pskovsky, Y.P.; Efremov, Y.N.; Kukarkina, N.P.; Kurochkin, N.E.; Medvedeva, G.I. (1971). "The third edition, containing information on 20,437 variable stars discovered and designated till 1968". General Catalogue of Variable Stars (3rd ed.). Bibcode:1971GCVS3.C......0K.
  5. Evans, D.S. (20–24 June 1966). "The revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
  6. Gliese, W. & Jahreiß, H. (1991). "Gl 388". Preliminary Version of the Third Catalogue of Nearby Stars. Retrieved 22 November 2014.
  7. "The One Hundred Nearest Star Systems". Georgia State University. 1 January 2009. Retrieved 25 September 2009.
  8. 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. S2CID 15833388.
  9. 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.
  10. Rojas-Ayala, Bárbara; Covey, Kevin R.; Muirhead, Philip S.; Lloyd, James P. (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. S2CID 41902340.
  11. 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. S2CID 8672566.
  12. 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. S2CID 118623086.
  13. "V* AD Leo – Flare Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 25 September 2009.
  14. 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. S2CID 15159121.
  15. 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.
  16. 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.
  17. Osten, Rachel A.; Bastian, T.S. (February 2008). "Ultra-high 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. S2CID 6953897.
  18. 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.
  19. Crespo-Chacón, I.; Montes, D.; García-Alvarez, D.; Fernández-Figueroa, M.J.; López-Santiago, J.; Foing, B.H. (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. S2CID 119092601.
  20. Christian, D.J.; Mathioudakis, M.; Bloomfield, D.S.; Dupuis, J.; Keenan, F.P.; Pollacco, D.L.; Malina, R.F. (August 2006). "Opacity in the upper atmospheres of active stars. II. AD Leonis" (PDF). Astronomy and Astrophysics. 454 (3): 889–894. arXiv:astro-ph/0602447. Bibcode:2006A&A...454..889C. doi:10.1051/0004-6361:20054404. S2CID 29588514.
  21. Johnstone, C.P.; Güdel, M. (June 2015). "The coronal temperatures of low-mass main-sequence stars". Astronomy & Astrophysics. 578: 4. arXiv:1505.00643. Bibcode:2015A&A...578A.129J. doi:10.1051/0004-6361/201425283. S2CID 117151984. A129.
  22. 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.
  23. Leinert, C.; Henry, T.; Glindemann, A.; McCarthy, D. W., Jr. (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.
  24. Oppenheimer, B.R.; Golimowski, D.A.; Kulkarni, S.R.; Matthews, K.; Nakajima, T.; Creech-Eakman, M.; Durrance, S.T. (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. S2CID 119092593.
  25. 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.
  26. Tuomi, M.; Jones, H. R. A.; Butler, R. P.; Arriagada, P.; Vogt, S. S.; Burt, J.; et al. (11 June 2019). "Frequency of planets orbiting M dwarfs in the Solar neighbourhood". arXiv:1906.04644 [astro-ph.EP].
  27. Carleo, I.; Malavolta, L.; Lanza, A.F.; Damasso, M.; Desidera, S.; Borsa, F.; et al. (2020). "The GAPS Programme at TNG XXI – A GIARPS case-study of known young planetary candidates: Confirmation of HD 285507 b and refutation of AD Leo b". Astronomy & Astrophysics. A5: 638. arXiv:2002.10562. Bibcode:2020A&A...638A...5C. doi:10.1051/0004-6361/201937369. S2CID 211296466.
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