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36 Serpentis
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Serpens
Right ascension	15h 51m 15.59418s
Declination	−03° 05′ 25.7938″
Apparent magnitude (V)	5.09 (5.2 + 7.8)
Characteristics
Spectral type	A3Vn or A2IV-Vn (A7 + G0)
U−B color index	+0.07
B−V color index	+0.12
Astrometry
Radial velocity (Rv)	−8 km/s
Proper motion (μ)	RA: −91.09 mas/yr ; Dec.: −28.21 mas/yr
Parallax (π)	20.10 ± 0.33 mas
Distance	162 ± 3 ly ; (49.8 ± 0.8 pc)
Absolute magnitude (MV)	1.61
Orbit
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
Mass	2.04 M☉
Radius	1.65 R☉
Luminosity	19.13 L☉
Surface gravity (log g)	3.89 cgs
Temperature	8246 K
Metallicity [Fe/H]	−2.00 dex
Rotational velocity (v sin i)	229 km/s
Age	723 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
Database references
SIMBAD	data

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 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

^ ^a ^b ^c ^d ^e ^f 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.
^ ^a ^b ^c ^d ^e 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.
^ ^a ^b ^c 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.
^ ^a ^b 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.
^ ^a ^b 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.
^ ^a ^b ^c ^d ^e ^f 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.
^ ^a ^b Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
^ ^a ^b Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
^ ^a ^b ^c 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.
^ Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)". Astronomy & Astrophysics. 367 (Third ed.): 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754.
^ ^a ^b ^c ^d 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.
^ ^a ^b 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.
^ ^a ^b "36 Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-07-14.
^ 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.
^ 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.