36 Serpentis

36 Serpentis is a binary star[14] system in the equatorial constellation of Serpens. It has the Bayer designation b Serpentis, while 36 Serpentis is the Flamsteed designation.[13] The system is visible to the naked eye as a dim, white-hued point of light with a combined apparent visual magnitude of 5.09.[2] It is located 162 light years away from the Sun based on parallax,[1] and is moving closer with a radial velocity of −8 km/s.[8]

This article is about b Serpentis. It is not to be confused with β (Beta) Serpentis.
36 Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 15h 51m 15.59418s[1]
Declination −03° 05′ 25.7938″[1]
Apparent magnitude (V) 5.09[2] (5.2 + 7.8)[3]
Characteristics
Spectral type A3Vn[4] or A2IV-Vn[5] (A7 + G0)[6]
U−B color index +0.07[7]
B−V color index +0.12[7]
Astrometry
Radial velocity (Rv)−8[8] km/s
Proper motion (μ) RA: −91.09[1] mas/yr
Dec.: −28.21[1] mas/yr
Parallax (π)20.10 ± 0.33 mas[1]
Distance162 ± 3 ly
(49.8 ± 0.8 pc)
Absolute magnitude (MV)1.61[2]
Orbit[6]
Period (P)50.6±1.5 yr
Semi-major axis (a)0.400±0.006″
Eccentricity (e)0.8323±0.0047
Inclination (i)98.08±0.31°
Longitude of the node (Ω)74.00±0.31°
Periastron epoch (T)2002.78±0.17
Argument of periastron (ω)
(secondary)		72.84±0.91°
Details
36 Ser A
Mass2.04[9] M☉
Radius1.65[10] R☉
Luminosity19.13[2] L☉
Surface gravity (log g)3.89[11] cgs
Temperature8246[11] K
Metallicity [Fe/H]−2.00[11] dex
Rotational velocity (v sin i)229[12] km/s
Age723[9] Myr
Other designations
b Ser, 36 Ser, BD−02°4058, FK5 2249, GC 4210, HD 141851, HIP 77660, HR 5895, SAO 140801, WDS J15513-0305[13]
Database references
SIMBADdata

This is a spectroscopic binary star system with a long orbital period of 52.8 years and a high eccentricity of 0.83. The combined mass of the pair is 3.09±0.28 M☉.[6] Gray et al. (2017) found a merged stellar classification of A2IV-Vn for this system,[5] while Cowley et al. matched it with a class of A3Vn,[4] where the 'n' indicates "nebulous" lines caused by rapid rotation.

The primary component is a Lambda Boötis star, meaning that it has solar-like amounts of carbon, nitrogen, and oxygen, while containing very low amounts of iron peak elements.[15] It is an A7[6] class main sequence star of visual magnitude 5.2[3] that is spinning rapidly, showing a projected rotational velocity of 229.[12] The star is 723[9] million years old with around double the mass of the Sun. It is radiating 19[2] times the Sun's luminosity from its photosphere at an effective temperature of 8,246 K.[11]

The cooler secondary component, a G0 star,[6] is the source for the X-ray emission that has been detected coming from this system.[6] It has a visual magnitude of 7.8.[3]

References
  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  3. Docobo, José A.; et al. (2010). "EMCCD Speckle Interferometry with the 6 m Telescope: Astrometric Measurements, Differential Photometry, and Orbits". The Astronomical Journal. 140 (4): 1078–1083. Bibcode:2010AJ....140.1078D. doi:10.1088/0004-6256/140/4/1078.
  4. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  5. Gray, R. O.; et al. (July 2017). "The Discovery of λ Bootis Stars: The Southern Survey I". The Astronomical Journal. 154 (1): 11. Bibcode:2017AJ....154...31G. doi:10.3847/1538-3881/aa6d5e. 31.
  6. Mason, Brian D.; et al. (September 2010). "Binary Star Orbits. IV. Orbits of 18 Southern Interferometric Pairs". The Astronomical Journal. 140 (3): 735–743. Bibcode:2010AJ....140..735M. doi:10.1088/0004-6256/140/3/735.
  7. Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  8. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
  9. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  10. Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)". Astronomy & Astrophysics (Third ed.). 367: 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754.
  11. Prugniel, Ph.; et al. (1986). "The atmospheric parameters and spectral interpolator for the MILES stars". Astronomy & Astrophysics. 531: A165. arXiv:1104.4952. Bibcode:2011A&A...531A.165P. doi:10.1051/0004-6361/201116769. S2CID 54940439.
  12. Royer, F.; et al. (2007). "Rotational velocities of A-type stars. III. Velocity distributions". Astronomy & Astrophysics. 463 (2): 671–682. arXiv:astro-ph/0610785. Bibcode:2007A&A...463..671R. doi:10.1051/0004-6361:20065224. S2CID 18475298.
  13. "36 Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-07-14.
  14. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  15. Nikolov, G.; et al. (April 2008). "Spectroscopic orbit determination of two metal-weak dwarf stars: HD64491 and HD141851". Contributions of the Astronomical Observatory Skalnaté Pleso. 38 (2): 433–434. Bibcode:2008CoSka..38..433N.
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