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BO Lyncis

BO Lyncis
Location of BO Lyncis (circled)
Observation data
Epoch J2000[1]      Equinox J2000[1]
Constellation Lynx
Right ascension 08h 43m 01.21223s
Declination +40° 59′ 51.7692″
Apparent magnitude (V) 11.48[2]
Characteristics
Spectral type A5V-A8V + late A,[3] kA6hA5mA9 (combined)[4]
B−V color index +0.32[2]
J−H color index +0.125[5]
J−K color index +0.128[5]
Variable type Delta Scuti variable
Astrometry
Radial velocity (Rv)23.48 ± 1.23[6] km/s
Proper motion (μ) RA: −4.899[1] mas/yr
Dec.: 1.485[1] mas/yr
Parallax (π)0.7432 ± 0.0194 mas[1]
Distance4,400 ± 100 ly
(1,350 ± 40 pc)
Absolute magnitude (MV)2.2 (A)
Orbit[3]
PrimaryBO Lyncis A
CompanionBO Lyncis B
Period (P)34.53±0.10 yr
Semi-major axis (a)5.19±0.18 AU (minimum)
Eccentricity (e)0.64±0.03
Inclination (i)~42°
Periastron epoch (T)2452047.5±94.0
Argument of periastron (ω)
(secondary)		185.5±3.1°
Details[3]
BO Lyncis A
Mass1.76 M☉
Luminosity13.6 (maximum), 9.4 (minimum) L☉
Metallicity [Fe/H]−0.3[7] dex
Rotational velocity (v sin i)probably <40[7] km/s
BO Lyncis B
Mass1.67 M☉
Luminosity~8.4 L☉
Other designations
BO Lyn, Gaia DR3 913186875504602624, TIC 99091734, TYC 2985-1044-1, GSC 02985-01044, 2MASS J08430121+4059517[8]
Database references
SIMBADdata

BO Lyncis, abbreviated BO Lyn and otherwise referred to as GSC 02985-01044, is a white-hued binary star in the northern constellation of Lynx. With an apparent magnitude of 11.49, it is too faint to be seen by the naked eye but can be observed using a telescope with an aperture of 60 mm (2.4 in) or larger.[9] It is located at a distance of 1,350 parsecs (4,400 light-years) according to Gaia EDR3 parallax measurements, and is receding farther away from the Sun at a heliocentric radial velocity of 23.48 km/s.

It was first discovered to be a Delta Scuti variable in 1994 during a survey of blue horizontal branch stars,[10] and was subsequently assigned its variable-star designation in 1997.[11]

Stellar properties

The primary star is an A-type main-sequence star between the spectral types A5V and A8V, with a mass of approximately 1.76 M☉ and a luminosity fluctuating between 9.4 L☉ and 13.6 L☉. A detailed spectral type of kA6hA5mA9 indicates that the classification would be A6 based on calcium K-lines, A5 based on calcium H-lines, and A9 based on the spectral lines of other metals.

A light curve for BO Lyncis, plotted from TESS data[12]

It has been described as a high-amplitude Delta Scuti variable (HADS), also known as an AI Velorum star, with a period of 0.0933584 days[7] (10.7114 cycles/day) and an amplitude of 0.23 mag.[3] The relatively short period signals that the star has a low metallicity of around −0.3, meaning it has only 10−0.3 ≈ 50% as much iron content as the Sun.[7] In 2005, the period was found to be steadily decreasing at a rate of −1.5×10−10 days/day (0.056 d/Ma), which would later be revised to (1.52±0.26)×10−3 d/Ma by Li et al. (2018).[3] Concurrently, two additional possible pulsation frequencies were discovered, at 15.81 and 13.60 cycles/day.[13]

The secondary star has a minimum mass of 0.95±0.30 M☉, which, coupled with the binary's blue color, suggests that it is an A- or F-type main-sequence star or a dim degenerate star. If the former is true, its luminosity is non-negligible, decreasing the apparent amplitude of the pulsating star (which happens to be relatively small for a HADS). Assuming an amplitude typical of the primary's spectral type at 0.40 mag, the luminosity of the secondary can be derived at ~8.4 L☉, corresponding to a 1.67 M☉ late A-type main-sequence star. This places the inclination of the system at about 42°.[3]

Stellar kinematics measurements imply that the star belongs to the old disk population of the Milky Way, though its distance above the Galactic plane is 628 parsecs (2,050 ly), which is two scale heights of the old disk population.[7]

References

  1. ^ a b c d 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.
  2. ^ a b Høg, E.; et al. (February 2000). "The Tycho-2 Catalogue of the 2.5 Million Brightest Stars". Astronomy and Astrophysics. 355 (1): L27–L30. Bibcode:2000A&A...355L..27H.
  3. ^ a b c d e f Li, Lin-Jia; Qian, Sheng-Bang; Zhang, Jia; Zhu, Li-Ying; Liao, Wen-Ping (2018). "High amplitude δ Scuti star BO Lyn with evidence of a late A-type companion in an elliptical orbit". Research in Astronomy and Astrophysics. 18 (1): 011. Bibcode:2018RAA....18...11L. doi:10.1088/1674-4527/18/1/11. ISSN 1674-4527.
  4. ^ Tian 田, Xiao-man 晓慢; Wang 王, Zhi-hua 志华; Zhu 朱, Li-ying 俐颖; Yang 杨, Xiao-Ling 晓玲 (1 May 2023). "A New Catalog of Am-type Chemically Peculiar Stars Based on LAMOST". The Astrophysical Journal Supplement Series. 266 (1): 14. Bibcode:2023ApJS..266...14T. doi:10.3847/1538-4365/acc4b5. ISSN 0067-0049.
  5. ^ a b 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.
  6. ^ Zhang, Li-yun; Su, Tianhao; Misra, Prabhakar; Han, Xianming L.; Meng, Gang; Pi, Qingfeng; Yang, Jiawei (1 January 2023). "Stellar Parameters and Spectroscopic Properties of TESS Objects Observed in the LAMOST Low- and Medium-resolution Spectral Survey". The Astrophysical Journal Supplement Series. 264 (1): 17. Bibcode:2023ApJS..264...17Z. doi:10.3847/1538-4365/ac9b28. ISSN 0067-0049.
  7. ^ a b c d e Kinman, T. D. (1998). "The δ Scuti Star GSC 2985-01044". Publications of the Astronomical Society of the Pacific. 110 (753): 1277–1289. Bibcode:1998PASP..110.1277K. doi:10.1086/316259. ISSN 0004-6280.
  8. ^ "BO Lyncis". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 19 December 2024.
  9. ^ North, Gerald; James, Nick (2014). Observing Variable Stars, Novae and Supernovae. Cambridge University Press. p. 24. ISBN 978-1-107-63612-5.
  10. ^ Kinman, T. D.; Suntzeff, N. B.; Kraft, R. P. (1994). "The structure of the galactic halo outside the solar circle as traced by the blue horizontal branch stars". The Astronomical Journal. 108: 1722. Bibcode:1994AJ....108.1722K. doi:10.1086/117191.
  11. ^ Kazarovets, E. V.; Samus, N. N. (23 April 1997). "The 73th Name-List of Variable Stars". Information Bulletin on Variable Stars. 4471 (1). Konkoly Observatory, Budapest: International Astronomical Union. Bibcode:1997IBVS.4471....1K.
  12. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 19 December 2024.
  13. ^ Hintz, Eric G.; Bush, Tabitha C.; Rose, Michael B. (2005). "Monitoring Three Less-Studied δ Scuti Variables: GW Ursae Majoris, BO Lyncis, and AN Lyncis". The Astronomical Journal. 130 (6): 2876–2883. Bibcode:2005AJ....130.2876H. doi:10.1086/497392. ISSN 0004-6256.
Quelle: https://en.wikipedia.org/wiki/BO_Lyncis