36 Serpentis

36 Serpentis
Observation data
Epoch J2000.0      Equinox 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
Distance162 ± 3 ly
(49.8 ± 0.8 pc)
Absolute magnitude (MV)1.61
Orbit
Primary36 Ser A
Secondary36 Ser B
Period (P)1,073 days
Eccentricity (e)0.7
Semi-amplitude (K1)
(primary)		6 km/s
Orbit
Primary36 Ser AB
Secondary36 Ser C
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
Mass1.97 M☉
Radius2.25 R☉
Luminosity19.13 L☉
Surface gravity (log g)3.89 cgs
Temperature8,213 K
Metallicity [Fe/H]−2.00 dex
Rotational velocity (v sin i)229 km/s
Age710 Myr
36 Ser B
Mass≥0.37 and ≤0.50 M☉
36 Ser C
Mass1.27 M☉
Radius1.26 R☉
Temperature6,255 K
Age710 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
SIMBADdata

36 Serpentis is a triple star system in the equatorial constellation of Serpens. It has the Bayer designation b Serpentis, while 36 Serpentis is the Flamsteed designation. 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. It is located 162 light years away from the Sun based on parallax, and is moving closer with a radial velocity of −8 km/s.

Characteristics

The system consists of two spectroscopic binaries. The inner pair contains components A and B, while the outer pair contains components AB and C. The age of the whole system is estimated at 710 million years.

The components AB and C orbit each other over a long orbital period of 52.8 years and a high eccentricity of 0.83. Gray et al. (2017) found a merged stellar classification of A2IV-Vn for this system, while Cowley et al. matched it with a class of A3Vn, where the 'n' indicates "nebulous" lines caused by rapid rotation.

The primary component, 36 Serpentis A, is an A7-class main sequence star of visual magnitude 5.2. It is spinning rapidly, showing a projected rotational velocity of 229 km/s. It was once thought to be a Lambda Boötis star but this is now disputed. The star is 710 million years old with 1.97 times the mass of the Sun and 2.25 times the Sun's radius. It is radiating 19 times the Sun's luminosity from its photosphere at an effective temperature of 8,213 K.

The secondary, 36 Serpentis B, has been detected only by spectroscopy. It has an orbital period of 1,073 days (2.94 years) and a high eccentricity of 0.7. Interferometric observations have failed to detect this star, implying a luminosity-derived mass less than 0.50 M☉. The radial velocity data suggest a mass of at least 0.37 solar masses. It may be a faint red dwarf or a white dwarf. 36 Ser B is likely the source for the X-ray emission that has been detected coming from this system.

The tertiary, 36 Serpentis C, is a G0 star with a visual magnitude of 7.8. It has 1.27 times the Sun's mass, 1.26 times the Sun's radius, and an effective temperature of 6,555 K.

References

  1. 1 2 3 4 5 6 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. 1 2 3 4 5 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. 1 2 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. 1 2 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. 1 2 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. 1 2 3 4 5 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. 1 2 Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  8. 1 2 Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
  9. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Waisberg, Idel; Klein, Ygal; Katz, Boaz (2023-06-01). "Binarity and beyond in A stars – I. Survey description and first results of VLTI/GRAVITY observations of VAST targets with high Gaia–Hipparcos accelerations". Monthly Notices of the Royal Astronomical Society. 521 (4): 5232–5254. arXiv:2206.05251. Bibcode:2023MNRAS.521.5232W. doi:10.1093/mnras/stad872. ISSN 0035-8711.
  10. 1 2 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.
  11. 1 2 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.
  12. 1 2 "36 Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-07-14.
  13. ↑ 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.