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Lacaille 8760

January 01, 1970

Lacaille 8760 (AX Microscopii) is a red dwarf star in the constellation Microscopium. It is one of the nearest stars to the Sun at about 12.9 light-years' distance, and the brightest M-class main-sequence star in Earth's night sky, although it is generally too faint to be seen without a telescope. At an apparent magnitude of +6.7, it may only be visible to the unaided eye under exceptionally good viewing conditions, under dark skies.

Lacaille 8760
Image of Lacaille 8760 (circled) in Bode's Uranographia (1801).[1] In the corresponding catalog this star is listed as № 36 in constellation Microscopium.[2]

Observation data
Epoch J2000      Equinox J2000
Constellation Microscopium
Right ascension 21h 17m 15.269s[3]
Declination −38° 52′ 02.51″[3]
Apparent magnitude (V) 6.67[4]
Characteristics
Spectral type M0Ve[5][6]
U−B color index +1.165[5]
B−V color index +1.395[5]
Variable type Flare star
Astrometry
Radial velocity (Rv)+20.7[6] km/s
Proper motion (μ) RA: −3,258.553 mas/yr[3]
Dec.: −1,145.396 mas/yr[3]
Parallax (π)251.9124 ± 0.0352 mas[7]
Distance12.947 ± 0.002 ly
(3.9696 ± 0.0006 pc)
Absolute magnitude (MV)8.69[4]
Details
Mass0.60[4] M☉
Radius0.51[8] R☉
Luminosity (bolometric)0.072[9] L☉
Luminosity (visual, LV)0.029 L☉
Surface gravity (log g)4.78[8] cgs
Temperature3,800[10] K
Metallicity [Fe/H]−0.01±0.04[11] dex
Rotation40±12 d[12]
Rotational velocity (v sin i)3.3[6] km/s
Age4.8±2.9[13] Gyr
Other designations
AX Microscopii, AX Mic, CD−39°14192, GJ 825, HD 202560, HIP 105090, LHS 66[5]
Database references
SIMBADdata
Exoplanet Archivedata
ARICNSdata
Lacaille 8760
Location of Lacaille 8760 in the constellation Microscopium

This star was originally listed in a 1763 catalog that was published posthumously by the French Abbé Nicolas-Louis de Lacaille. He observed it in the southern sky while working from an observatory at the Cape of Good Hope.[14] Number 8760 was assigned to this star in the 1847 edition of Lacaille's catalogue of 9,766 stars by Francis Baily.[15]

In the past, Lacaille 8760 has been classified anywhere from spectral class K7 down to M2. In 1979, the Irish astronomer Patrick Byrne discovered that it is a flare star,[16] and it was given the variable star designation AX Microscopii, or AX Mic. As a flare star it is relatively quiescent.

An ultraviolet band light curve for a flare on AX Microscopii, adapted from Byrne (1981)[16]

Lacaille 8760 is one of the largest and brightest red dwarfs known, with about 60%[4] the mass and 51%[8] the radius of the Sun. It is about five[13] billion years old and is spinning at a projected rotational velocity of 3.3 km/s,[6] giving it a rotation period of roughly 40 days.[12] The star is radiating 7.2%[9] of the luminosity of the Sun from its photosphere at an effective temperature of 3,800 K.[10]

Despite efforts by astronomers, as of 2011 no planets had been detected in orbit around this star.[17]

Lacaille 8760 orbits around the galaxy with a relatively high ellipticity of 0.23.[18] Its closest approach to the Sun occurred about 20,000 years ago when it came within 12 light-years (3.7 parsecs).[19] Due to its low mass (60% of the Sun), it has an expected lifespan of about 75 billion (7.5 × 1010) years,[20] seven times longer than the Sun's.

References edit

  1. ^ e-rara.ch. Johann Elert Bode. Uranographia star atlas (1801), Tabula XVI
  2. ^ Johann Elert Bode. Allgemeine Beschreibung und Nachweisung der Gestirne (1801), Page 67
  3. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. ^ a b c d "The One Hundred Nearest Star Systems", RECONS, Georgia State University, retrieved 2015-06-25.
  5. ^ a b c d "V* AX Mic -- Flare Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-02-18.
  6. ^ a b c d Torres, C. A. O.; et al. (December 2006), "Search for associations containing young stars (SACY). I. Sample and searching method", Astronomy and Astrophysics, 460 (3): 695–708, arXiv:astro-ph/0609258, Bibcode:2006A&A...460..695T, doi:10.1051/0004-6361:20065602, S2CID 16080025. See the online data.
  7. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  8. ^ a b c Takeda, Genya; et al. (February 2007), "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series, 168 (2): 297–318, arXiv:astro-ph/0607235, Bibcode:2007ApJS..168..297T, doi:10.1086/509763, S2CID 18775378, retrieved 2011-08-26.
  9. ^ a b Moro-Martín, A.; et al. (March 2015). "Does the Presence of Planets Affect the Frequency and Properties of Extrasolar Kuiper Belts? Results from the Herschel Debris and Dunes Surveys". The Astrophysical Journal. 801 (2): 28. arXiv:1501.03813. Bibcode:2015ApJ...801..143M. doi:10.1088/0004-637X/801/2/143. S2CID 55170390.Vizier catalog entry
  10. ^ a b Gautier, Thomas N., III; et al. (September 2007), "Far-Infrared Properties of M Dwarfs", The Astrophysical Journal, 667 (1): 527–536, arXiv:0707.0464, Bibcode:2007ApJ...667..527G, doi:10.1086/520667, S2CID 15732144.{{citation}}: CS1 maint: multiple names: authors list (link)
  11. ^ Lindgren, Sara; Heiter, Ulrike (2017). "Metallicity determination of M dwarfs. Expanded parameter range in metallicity and effective temperature". Astronomy and Astrophysics. 604: A97. arXiv:1705.08785. Bibcode:2017A&A...604A..97L. doi:10.1051/0004-6361/201730715. S2CID 119216828.
  12. ^ a b Byrne, P. B.; Doyle, J. G. (January 1989), "Activity in late-type dwarfs. III - Chromospheric and transition region line fluxes for two dM stars", Astronomy and Astrophysics, 208 (1–2): 159–165, Bibcode:1989A&A...208..159B.
  13. ^ a b Boehle, A.; et al. (October 2019), "Combining high-contrast imaging and radial velocities to constrain the planetary architectures of nearby stars", Astronomy & Astrophysics, 630: 17, arXiv:1907.04334, Bibcode:2019A&A...630A..50B, doi:10.1051/0004-6361/201935733, S2CID 195874049, A50.
  14. ^ Croswell, Ken (July 2003), "The Brightest Red Dwarf", Sky & Telescope: 32, retrieved 2011-02-18.
  15. ^ Francis Baily. A Catalogue of 9766 Stars (1847), Page 219
  16. ^ a b Byrne, P. B. (April 1981), "Gliese 825 - A new flare star", Monthly Notices of the Royal Astronomical Society, 195 (2): 143–147, Bibcode:1981MNRAS.195..143B, doi:10.1093/mnras/195.2.143.
  17. ^ Carson, J. C.; et al. (December 2011), "Low-mass evolution - Zero-age main sequence to asymptotic giant branch", The Astrophysical Journal, 743 (2): 141, arXiv:1110.2191, Bibcode:2011ApJ...743..141C, doi:10.1088/0004-637X/743/2/141, S2CID 119270911.
  18. ^ 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.
  19. ^ García-Sánchez, J.; et al. (2001), "Stellar encounters with the solar system" (PDF), Astronomy and Astrophysics, 379 (2): 634–659, Bibcode:2001A&A...379..634G, doi:10.1051/0004-6361:20011330.
  20. ^ Despain, K. H. (December 1981), "Low-mass evolution - Zero-age main sequence to asymptotic giant branch", Astrophysical Journal, Part 1, 251: 639–653, Bibcode:1981ApJ...251..639D, doi:10.1086/159510.

External links edit

  • SolStation article

January 01, 1970
lacaille, 8760, microscopii, dwarf, star, constellation, microscopium, nearest, stars, about, light, years, distance, brightest, class, main, sequence, star, earth, night, although, generally, faint, seen, without, telescope, apparent, magnitude, only, visible. Lacaille 8760 AX Microscopii is a red dwarf star in the constellation Microscopium It is one of the nearest stars to the Sun at about 12 9 light years distance and the brightest M class main sequence star in Earth s night sky although it is generally too faint to be seen without a telescope At an apparent magnitude of 6 7 it may only be visible to the unaided eye under exceptionally good viewing conditions under dark skies Lacaille 8760Image of Lacaille 8760 circled in Bode s Uranographia 1801 1 In the corresponding catalog this star is listed as 36 in constellation Microscopium 2 Observation dataEpoch J2000 Equinox J2000 Constellation Microscopium Right ascension 21h 17m 15 269s 3 Declination 38 52 02 51 3 Apparent magnitude V 6 67 4 Characteristics Spectral type M0Ve 5 6 U B color index 1 165 5 B V color index 1 395 5 Variable type Flare star AstrometryRadial velocity Rv 20 7 6 km sProper motion m RA 3 258 553 mas yr 3 Dec 1 145 396 mas yr 3 Parallax p 251 9124 0 0352 mas 7 Distance12 947 0 002 ly 3 9696 0 0006 pc Absolute magnitude MV 8 69 4 DetailsMass0 60 4 M Radius0 51 8 R Luminosity bolometric 0 072 9 L Luminosity visual LV 0 029 L Surface gravity log g 4 78 8 cgsTemperature3 800 10 KMetallicity Fe H 0 01 0 04 11 dexRotation40 12 d 12 Rotational velocity v sin i 3 3 6 km sAge4 8 2 9 13 Gyr Other designationsAX Microscopii AX Mic CD 39 14192 GJ 825 HD 202560 HIP 105090 LHS 66 5 Database referencesSIMBADdataExoplanet ArchivedataARICNSdata Lacaille 8760Location of Lacaille 8760 in the constellation Microscopium This star was originally listed in a 1763 catalog that was published posthumously by the French Abbe Nicolas Louis de Lacaille He observed it in the southern sky while working from an observatory at the Cape of Good Hope 14 Number 8760 was assigned to this star in the 1847 edition of Lacaille s catalogue of 9 766 stars by Francis Baily 15 In the past Lacaille 8760 has been classified anywhere from spectral class K7 down to M2 In 1979 the Irish astronomer Patrick Byrne discovered that it is a flare star 16 and it was given the variable star designation AX Microscopii or AX Mic As a flare star it is relatively quiescent An ultraviolet band light curve for a flare on AX Microscopii adapted from Byrne 1981 16 Lacaille 8760 is one of the largest and brightest red dwarfs known with about 60 4 the mass and 51 8 the radius of the Sun It is about five 13 billion years old and is spinning at a projected rotational velocity of 3 3 km s 6 giving it a rotation period of roughly 40 days 12 The star is radiating 7 2 9 of the luminosity of the Sun from its photosphere at an effective temperature of 3 800 K 10 Despite efforts by astronomers as of 2011 no planets had been detected in orbit around this star 17 Lacaille 8760 orbits around the galaxy with a relatively high ellipticity of 0 23 18 Its closest approach to the Sun occurred about 20 000 years ago when it came within 12 light years 3 7 parsecs 19 Due to its low mass 60 of the Sun it has an expected lifespan of about 75 billion 7 5 1010 years 20 seven times longer than the Sun s References edit e rara ch Johann Elert Bode Uranographia star atlas 1801 Tabula XVI Johann Elert Bode Allgemeine Beschreibung und Nachweisung der Gestirne 1801 Page 67 a b c Brown A G A et al Gaia collaboration August 2018 Gaia Data Release 2 Summary of the contents and survey properties Astronomy amp Astrophysics 616 A1 arXiv 1804 09365 Bibcode 2018A amp A 616A 1G doi 10 1051 0004 6361 201833051 Gaia DR2 record for this source at VizieR a b c d The One Hundred Nearest Star Systems RECONS Georgia State University retrieved 2015 06 25 a b c d V AX Mic Flare Star SIMBAD Centre de Donnees astronomiques de Strasbourg retrieved 2011 02 18 a b c d Torres C A O et al December 2006 Search for associations containing young stars SACY I Sample and searching method Astronomy and Astrophysics 460 3 695 708 arXiv astro ph 0609258 Bibcode 2006A amp A 460 695T doi 10 1051 0004 6361 20065602 S2CID 16080025 See the online data Brown A G A et al Gaia collaboration 2021 Gaia Early Data Release 3 Summary of the contents and survey properties Astronomy amp Astrophysics 649 A1 arXiv 2012 01533 Bibcode 2021A amp A 649A 1G doi 10 1051 0004 6361 202039657 S2CID 227254300 Erratum doi 10 1051 0004 6361 202039657e Gaia EDR3 record for this source at VizieR a b c Takeda Genya et al February 2007 Structure and Evolution of Nearby Stars with Planets II Physical Properties of 1000 Cool Stars from the SPOCS Catalog The Astrophysical Journal Supplement Series 168 2 297 318 arXiv astro ph 0607235 Bibcode 2007ApJS 168 297T doi 10 1086 509763 S2CID 18775378 retrieved 2011 08 26 a b Moro Martin A et al March 2015 Does the Presence of Planets Affect the Frequency and Properties of Extrasolar Kuiper Belts Results from the Herschel Debris and Dunes Surveys The Astrophysical Journal 801 2 28 arXiv 1501 03813 Bibcode 2015ApJ 801 143M doi 10 1088 0004 637X 801 2 143 S2CID 55170390 Vizier catalog entry a b Gautier Thomas N III et al September 2007 Far Infrared Properties of M Dwarfs The Astrophysical Journal 667 1 527 536 arXiv 0707 0464 Bibcode 2007ApJ 667 527G doi 10 1086 520667 S2CID 15732144 a href Template Citation html title Template Citation citation a CS1 maint multiple names authors list link Lindgren Sara Heiter Ulrike 2017 Metallicity determination of M dwarfs Expanded parameter range in metallicity and effective temperature Astronomy and Astrophysics 604 A97 arXiv 1705 08785 Bibcode 2017A amp A 604A 97L doi 10 1051 0004 6361 201730715 S2CID 119216828 a b Byrne P B Doyle J G January 1989 Activity in late type dwarfs III Chromospheric and transition region line fluxes for two dM stars Astronomy and Astrophysics 208 1 2 159 165 Bibcode 1989A amp A 208 159B a b Boehle A et al October 2019 Combining high contrast imaging and radial velocities to constrain the planetary architectures of nearby stars Astronomy amp Astrophysics 630 17 arXiv 1907 04334 Bibcode 2019A amp A 630A 50B doi 10 1051 0004 6361 201935733 S2CID 195874049 A50 Croswell Ken July 2003 The Brightest Red Dwarf Sky amp Telescope 32 retrieved 2011 02 18 Francis Baily A Catalogue of 9766 Stars 1847 Page 219 a b Byrne P B April 1981 Gliese 825 A new flare star Monthly Notices of the Royal Astronomical Society 195 2 143 147 Bibcode 1981MNRAS 195 143B doi 10 1093 mnras 195 2 143 Carson J C et al December 2011 Low mass evolution Zero age main sequence to asymptotic giant branch The Astrophysical Journal 743 2 141 arXiv 1110 2191 Bibcode 2011ApJ 743 141C doi 10 1088 0004 637X 743 2 141 S2CID 119270911 Allen C Herrera M A April 1998 The Galactic Orbits of Nearby UV Ceti Stars Revista Mexicana de Astronomia y Astrofisica 34 37 46 Bibcode 1998RMxAA 34 37A Garcia Sanchez J et al 2001 Stellar encounters with the solar system PDF Astronomy and Astrophysics 379 2 634 659 Bibcode 2001A amp A 379 634G doi 10 1051 0004 6361 20011330 Despain K H December 1981 Low mass evolution Zero age main sequence to asymptotic giant branch Astrophysical Journal Part 1 251 639 653 Bibcode 1981ApJ 251 639D doi 10 1086 159510 External links editSolStation article Retrieved from https en wikipedia org w index php title Lacaille 8760 amp oldid 1170006452, wikipedia, wiki, book, books, library,

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