25 Serpentis

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25 Serpentis
Serpens constellation map.svg
Red circle.svg
Location of 25 Serpentis (circled)
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Serpens [1]
Right ascension 15h 46m 05.63636s [2]
Declination −01° 48′ 15.0830″ [2]
Apparent magnitude  (V)5.37 - 5.40 [3]
Characteristics
Spectral type B8IV/V [4]
U−B color index −0.40 [5]
B−V color index −0.05 [5]
Variable type SPB [6]
Astrometry
Radial velocity (Rv)9.50±0.3 [7] km/s
Proper motion (μ)RA: −23.15 [2] mas/yr
Dec.: −30.50 [2] mas/yr
Parallax (π)7.25±0.31  mas [2]
Distance 450 ± 20  ly
(138 ± 6  pc)
Absolute magnitude  (MV)−0.3 [1]
Orbit [8]
Period (P)38.927±0.004
Eccentricity (e)0.731±0.006
Periastron epoch (T)2450132.80±0.06
Argument of periastron (ω)
(secondary)		201.8±0.8°
Semi-amplitude (K1)
(primary)		43.1±0.7 km/s
Semi-amplitude (K2)
(secondary)		86±1 km/s
Details [9]
Mass 4.1  M☉
Luminosity 383  L☉
Temperature 13,932  K
Rotational velocity (v sin i)80 km/s
Other designations
A2 Ser, [10] 25 Ser, PT Ser, HD 140873, HIP 77227, HR  5863, SAO 140740, BD−01°3092
Database references
SIMBAD data

25 Serpentis is a star system in the constellation of Serpens Caput. With an apparent magnitude of 5.4, it is just barely visible to the naked eye. The system is estimated to be some 450 light-years (138 parsecs) based on its parallax. [2]

A light curve for PT Serpentis, plotted from Hipparcos data PTSerLightCurve.png
A light curve for PT Serpentis, plotted from Hipparcos data

25 Serpentis is a spectroscopic binary, [12] meaning that the individual components are too close to be resolved, but periodic Doppler shifts in their spectra indicate orbital motion. The system consists of a hot B-type giant and an A-type main-sequence star.[ citation needed ] The two stars orbit each other every 38.9 days, and have a very eccentric orbit, with an orbital eccentricity of 0.731. [8] The star was found to be a variable star in 1996, when the Hipparcos data was analyzed. [13] The primary is a slowly pulsating B-type star, which causes the system to vary by 0.03 magnitudes; [3] for that reason it was given the variable star designation PT Serpentis in 1999. [13]

References

  1. 1 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. XHIP record for this object at VizieR.
  2. 1 2 3 4 5 6 van Leeuwen, F.; et al. (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.
  3. 1 2 VSX; Otero, S. A (10 February 2012). "PT Serpentis". AAVSO Website. American Association of Variable Star Observers . Retrieved 28 May 2014.
  4. ↑ Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  5. 1 2 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. ↑ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  7. ↑ Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv: astro-ph/0406573 . Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID   119387088.
  8. 1 2 De Cat, P.; et al. (2000). "A study of bright southern slowly pulsating B stars. I. Determination of the orbital parameters and of the main frequency of the spectroscopic binaries". Astronomy and Astrophysics. 355: 1015–1030. Bibcode:2000A&A...355.1015D.
  9. ↑ Szewczuk, W.; Daszyńska-Daszkiewicz, J. (2015). "Identification of pulsational modes in rotating slowly pulsating B-type stars". Monthly Notices of the Royal Astronomical Society. 450 (2): 1585. arXiv: 1504.04490 . Bibcode:2015MNRAS.450.1585S. doi: 10.1093/mnras/stv715 .
  10. ↑ Hoffleit, D. (July 1979). "Discordances in Star Designations". Bulletin d'Information du Centre de Données Stellaires. 17 (17): 38. Bibcode:1979BICDS..17...38H.
  11. ↑ "Light Curve". Hipparcos ESA. ESA. Retrieved 17 February 2022.
  12. ↑ Petrie, R. M.; Phibbs, E. (1950). "Redetermination of the spectrographic orbits of iot Peg and 25 Ser". Publications of the Dominion Astrophysical Observatory Victoria. 8: 225. Bibcode:1950PDAO....8..225P.
  13. 1 2 Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Frolov, M. S.; Antipin, S. V.; Kireeva, N. N.; Pastukhova, E. N. (January 1999). "The 74th Special Name-list of Variable Stars". Information Bulletin on Variable Stars. 4659: 1–27. Bibcode:1999IBVS.4659....1K . Retrieved 12 September 2025.
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