Lambda Serpentis

Lambda Serpentis, Latinized from λ Serpentis, is a star in the constellation Serpens, in its head (Serpens Caput). It has an apparent visual magnitude of 4.43,[2] making it visible to the naked eye. Based upon parallax measurements, this star lies at a distance of about 38.9 light-years (11.9 parsecs) from Earth.[1] Lambda Serpentis is moving toward the Solar System with a radial velocity of 66.4 km s−1.[4] In about 166,000 years, this system will make its closest approach of the Sun at a distance of 7.371 ± 0.258 light-years (2.260 ± 0.079 parsecs), before moving away thereafter.[12]

Lambda Serpentis
Location of λ Serpentis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 15h 46m 26.61423s[1]
Declination +07° 21′ 11.0475″[1]
Apparent magnitude (V) 4.43[2]
Characteristics
Spectral type G0 V[3]
U−B color index +0.11[2]
B−V color index +0.60[2]
Variable type Suspected
Astrometry
Radial velocity (Rv)−66.4[4] km/s
Proper motion (μ) RA: −224.0±0.2 mas/yr[1]
Dec.: −69.8±0.3 mas/yr[1]
Parallax (π)83.92 ± 0.15 mas[1]
Distance38.87 ± 0.07 ly
(11.92 ± 0.02 pc)
Absolute magnitude (MV)4.01[5]
Details
Mass1.14[6] M☉
Radius1.060±0.152[7] R☉
Luminosity1.94[6] L☉
Surface gravity (log g)4.09[8] cgs
Temperature5,884±4.4[9] K
Metallicity [Fe/H]−0.03[8] dex
Rotational velocity (v sin i)3[10] km/s
Age3.8–6.7[11] Gyr
Other designations
λ Ser, 27 Serpentis, NSV 7246, BD+7°3023, HD 141004, HIP 77257, HR 5868, SAO 121186, 2MASS J15462661+0721109[3]
Database references
SIMBADdata

This star is 6% larger and 14% more massive than the Sun, although it has a similar stellar classification.[1] It is shining with nearly double the Sun's luminosity and this energy is being radiated from the star's outer atmosphere at an effective temperature of 5,884 K.[9] A periodicity of 1837 days (5.03 years) was suspected by Morbey & Griffith (1987),[13] but it is probably bound to stellar activity. However, McDonald Observatory team has set limits to the presence of one or more exoplanets[13] around Lambda Serpentis with masses between 0.16 and 2 Jupiter masses and average separations spanning between 0.05 and 5.2 Astronomical Units.

Planetary system

In 2020, a candidate planet was detected orbiting Lambda Serpentis (HD 141004). With a minimum mass of 0.043 MJ (13.6 M🜨) and an orbital period of 15 days, this would most likely be a hot Neptune.[14] The discovery of planet was confirmed in 2021.[15]

The Lambda Serpentis planetary system[15]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥ 0.0428+0.0047
−0.0045 MJ		 0.1238±0.002 15.5083+0.0016
−0.0018		 0.16+0.11
−0.10		 — —

References
  1. 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. Johnson, H. L.; Morgan, W. W. (1953). "Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas". Astrophysical Journal. 117: 313–352. Bibcode:1953ApJ...117..313J. doi:10.1086/145697. S2CID 18072563.
  3. "lam Ser -- Spectroscopic binary". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-12-15.
  4. Wilson, Ralph Elmer (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication. Washington: Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W.
  5. Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
  6. Valenti, J. A.; Fishcer, D. A. (2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". Astrophysical Journal Supplement Series. 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi:10.1086/430500.
  7. van Belle, Gerard T.; von Braun, Kaspar (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". The Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085. S2CID 18370219.
  8. Fuhrmann, Klaus (October 1998). "Nearby stars of the Galactic disk and halo". Astronomy and Astrophysics. 338: 161–183. Bibcode:1998A&A...338..161F.
  9. Kovtyukh; Soubiran, C.; Belik, S. I.; Gorlova, N. I. (2003). "High precision effective temperatures for 181 F-K dwarfs from line-depth ratios". Astronomy and Astrophysics. 411 (3): 559–564. arXiv:astro-ph/0308429. Bibcode:2003A&A...411..559K. doi:10.1051/0004-6361:20031378. S2CID 18478960.
  10. Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1): 1. Bibcode:1970CoAsi.239....1B.
  11. Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. S2CID 27151456.
  12. Dybczyński, P. A. (April 2006), "Simulating observable comets. III. Real stellar perturbers of the Oort cloud and their output", Astronomy and Astrophysics, 449 (3): 1233–1242, Bibcode:2006A&A...449.1233D, doi:10.1051/0004-6361:20054284
  13. Morbey, C. L.; Griffith, R. F. (1987). "On the reality of certain spectroscopic orbits". Astrophysical Journal. 317 (1): 343–352. Bibcode:1987ApJ...317..343M. doi:10.1086/165281.
  14. Hirsch, Lea A.; et al. (2021), "Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc", The Astronomical Journal, 161 (3): 134, arXiv:2012.09190, Bibcode:2021AJ....161..134H, doi:10.3847/1538-3881/abd639, S2CID 229297873.
  15. Rosenthal, Lee J.; Fulton, Benjamin J.; Hirsch, Lea A.; Isaacson, Howard T.; Howard, Andrew W.; Dedrick, Cayla M.; Sherstyuk, Ilya A.; Blunt, Sarah C.; Petigura, Erik A.; Knutson, Heather A.; Behmard, Aida; Chontos, Ashley; Crepp, Justin R.; Crossfield, Ian J. M.; Dalba, Paul A.; Fischer, Debra A.; Henry, Gregory W.; Kane, Stephen R.; Kosiarek, Molly; Marcy, Geoffrey W.; Rubenzahl, Ryan A.; Weiss, Lauren M.; Wright, Jason T. (2021), "The California Legacy Survey. I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades", The Astrophysical Journal Supplement Series, 255 (1): 8, arXiv:2105.11583, Bibcode:2021ApJS..255....8R, doi:10.3847/1538-4365/abe23c, S2CID 235186973

Further reading
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