Lambda Serpentis

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Lambda Serpentis
Diagram showing star positions and boundaries of the Serpens constellation and its surroundings
Cercle rouge 100%.svg

Location of λ Serpentis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 15h 46m 26.614s[1]
Declination +07° 21′ 11.04″[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: -224.00 ± 0.29[1] mas/yr
Dec.: -70.64 ± 0.27[1] mas/yr
Parallax (π) 82.48 ± 0.32[1] mas
Distance 39.5 ± 0.2 ly
(12.12 ± 0.05 pc)
Absolute magnitude (MV) 4.07
Details
Mass 1.14[5] M
Radius 1.060 ± 0.152[6] R
Luminosity 1.94[5] L
Surface gravity (log g) 4.09[7] cgs
Temperature 5,884 ± 4.4[8] K
Metallicity [Fe/H] −0.03[7] dex
Rotational velocity (v sin i) 3[9] km/s
Age 3.8–6.7[10] Gyr
Other designations
27 Serpentis, HR 5868, BD +7°3023, HD 141004, SAO 121186, HIP 77257.[3]

Lambda Serpentis (λ Ser, 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 from the Hipparcos satellite, this star lies at a distance of about 39.5 light-years (12.1 parsecs) from Earth.[1] This star is larger and more massive than the Sun, although it has a similar stellar classification.[3] 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.[8]

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.[11]

Hunt for substellar objects[edit]

A periodicity of 1837 days (5.03 years) was suspected by Morbey & Griffith (1987),[12] but it is probably bound to stellar activity. However, McDonald Observatory team has set limits to the presence of one or more planets[12] around Lambda Serpentis with masses between 0.16 and 2 Jupiter masses and average separations spanning between 0.05 and 5.2 Astronomical Units.

See also[edit]

References[edit]

  1. ^ 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.  Vizier catalog entry
  2. ^ a b c d 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. 
  3. ^ a b c "lam Ser -- Spectroscopic binary". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-12-15. 
  4. ^ a b Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953QB901.W495..... 
  5. ^ a b 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. 
  6. ^ 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. 
  7. ^ a b Fuhrmann, Klaus (October 1998). "Nearby stars of the Galactic disk and halo". Astronomy and Astrophysics 338: 161–183. Bibcode:1998A&A...338..161F. 
  8. ^ a b Kovtyukh et al.; 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. 
  9. ^ Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago 239 (1). Bibcode:1970CoAsi.239....1B. 
  10. ^ 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. 
  11. ^ 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 
  12. ^ a b 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. 

Further reading[edit]