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LN Andromedae

(Redirected from HR 8768)

LN Andromedae (LN And), also known as HD 217811, HR 8768, is a formerly suspected variable star[6] in the constellation Andromeda. Located approximately 458 parsecs (1,490 ly) away from Earth,[2] it shines with an apparent visual magnitude 6.41, thus it can be seen by the naked eye under very favourable conditions. Its spectral classification is B2V, meaning that it's a hot main sequence star, emitting light approximately with a blackbody spectrum at an effective temperature of 18,090 K.[14]

LN Andromedae

A light curve for LN Andromedae, plotted from Hipparcos data[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
LN Andromedae A
Right ascension 23h 02m 45.14786s[2]
Declination +44° 03′ 31.4984″[2]
Apparent magnitude (V) 6.37[3]
LN Andromedae B
Right ascension 23h 02m 45.60328s[4]
Declination +44° 03′ 37.2673″[4]
Apparent magnitude (V) 9.88[5]
Characteristics
A
Spectral type B2V[6]
Apparent magnitude (U) 5.8[7]
Apparent magnitude (B) 6.377[8]
Apparent magnitude (J) 6.368[9]
Apparent magnitude (H) 6.482[9]
Apparent magnitude (K) 6.496[9]
Variable type SPB?[10]
B
Spectral type A1V[11]
Astrometry
LN Andromedae A
Radial velocity (Rv)−11.30±0.1[12] km/s
Proper motion (μ) RA: 0.441±0.019[2] mas/yr
Dec.: −5.799±0.027[2] mas/yr
Parallax (π)2.1847 ± 0.0280 mas[2]
Distance1,490 ± 20 ly
(458 ± 6 pc)
Absolute magnitude (MV)−1.66[13]
LN Andromedae B
Proper motion (μ) RA: 0.238±0.012[4] mas/yr
Dec.: −5.813±0.016[4] mas/yr
Parallax (π)2.2005 ± 0.0182 mas[4]
Distance1,480 ± 10 ly
(454 ± 4 pc)
Details
A
Mass6.5[14] M☉
Radius3.1[15] R☉
Luminosity608[15] L☉
Surface gravity (log g)3.94±0.13[14] cgs
Temperature18090±730[14] K
Metallicity [Fe/H]−0.23[16] dex
Rotational velocity (v sin i)8±4[14] km/s
Age9.5±4.8[17] Myr
B
Mass2.1[16] M☉
Radius2.0[18] R☉
Luminosity13[19] L☉
Surface gravity (log g)4.1[16] cgs
Temperature9,843[16] K
Metallicity [Fe/H]−0.33[16] dex
Other designations
2MASS J23024514+4403314, HR 8768, BD+43°4378, HD 217811, SAO 52626, PPM 63745, HIP 113802, WDS J23028+4404AB
Database references
SIMBADdata

Companion

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In the Washington Double Star Catalog LN And has a faint optical companion star with an apparent magnitude of 9.88,[5] 7.5″ from LN And. The separation has increased from 4.0″ when it was discovered as a double in 1828.[20] The two stars share the same Hipparcos identifier HIP 113802, and have very similar parallaxes and proper motions.[2][4]

Variability

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In 1979, the blue magnitude of LN And was reported to vary by about 0.025 every 28 minutes. Such variability was not known for any class of variable, but the position in the Hertzsprung–Russell diagram at the main sequence (low luminosity) end of the same instability strip as the β Cephei stars would make high-overtone radial pulsations the likely cause.[13] LN And was added to the General Catalogue of Variable Stars as LN Andromedae,[6] but follow-up studies failed to find the same rapid variations, or any significant variations in brightness and it is now listed as probably constant.[21][6]

Analysis of Hipparcos photometry shows variability of about 0.0059 magnitudes with a main period of 3.25 d. The statistical threshold for these variations is at a level which is only met by 0.01% of stars.[3]

References

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  1. ^ "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
  2. ^ a b c d e f g 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.
  3. ^ a b Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331 (1): 45. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x.
  4. ^ a b c d e f 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.
  5. ^ a b "BD+43 4378B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 15, 2018.
  6. ^ a b c d N. N. Samus; O. V. Durlevich; et al. "LN And database entry". Combined General Catalog of Variable Stars (2017 ed.). CDS. Retrieved 2018-11-12.
  7. ^ Reed, B. C. (May 2003). "Catalog of Galactic OB Stars". The Astronomical Journal. 125 (5): 2531–2533. Bibcode:2003AJ....125.2531R. doi:10.1086/374771.
  8. ^ "LN Andromedae". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 15, 2018.
  9. ^ a b c Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  10. ^ "LN Andromedae". The International Variable Star Index. Retrieved 2022-03-04.
  11. ^ Lutz, T. E.; Lutz, J. H. (June 1977). "Spectral classification and UBV photometry of bright visual double stars". Astronomical Journal. 82: 431–434. Bibcode:1977AJ.....82..431L. doi:10.1086/112066.
  12. ^ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  13. ^ a b Jakate, S. M. (1979). "A new class of early-type ultra-short-period variables". The Astronomical Journal. 84: 1042. Bibcode:1979AJ.....84.1042J. doi:10.1086/112510.
  14. ^ a b c d e Lyubimkov, N.; Lambert, D. L.; Poklad, D. B.; Rachkovskaya, T. M.; Rostopchin, S. I. (February 2013). "Carbon, nitrogen and oxygen abundances in atmospheres of the 5-11 M☉ B-type main-sequence stars". Monthly Notices of the Royal Astronomical Society. 428 (4): 3497–3508. arXiv:1212.0987. Bibcode:2013MNRAS.428.3497L. doi:10.1093/mnras/sts287. S2CID 6924172.
  15. ^ a b Stassun, Keivan G.; et al. (September 2018). "The TESS Input Catalog and Candidate Target List". The Astronomical Journal. 156 (3): 102. arXiv:1706.00495. Bibcode:2018AJ....156..102S. doi:10.3847/1538-3881/aad050. ISSN 0004-6256. S2CID 73582386.
  16. ^ a b c d e Anders, F.; et al. (1 August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy and Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. S2CID 131780028.
  17. ^ Tezlaff, L. S.; Neuhäuser, R.; Hohle, N. N. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x.
  18. ^ Stassun, Keivan G.; et al. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. hdl:1721.1/124721. ISSN 0004-6256. S2CID 166227927.
  19. ^ 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.
  20. ^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  21. ^ Shaw, J. S.; Fraquelli, D. A.; Martins, D. H.; Andrew, S. B. (1983). "HR 8768 - an Ultra Short Period Variable?". Information Bulletin on Variable Stars. 2288: 1. Bibcode:1983IBVS.2288....1S.
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