Lambda Geminorum

Lambda Geminorum
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Gemini
Right ascension 07h 18m 05.58012s[1]
Declination +16° 32′ 25.3964″[1]
Apparent magnitude (V) 3.571[2]
Characteristics
Spectral type A3V[3]
U−B color index +0.167[2]
B−V color index +0.113[2]
Variable type Constant[4]
Astrometry
Radial velocity (Rv)–7.40[5] km/s
Proper motion (μ) RA: –44.43[6] mas/yr
Dec.: –36.61[6] mas/yr
Parallax (π)32.33 ± 0.20 mas[6]
Distance100.9 ± 0.6 ly
(30.9 ± 0.2 pc)
Absolute magnitude (MV)+1.13[7]
Details
Mass2.098[3] M☉
Radius2.7773±0.0469[3] R☉
Luminosity27.3901±0.3416[3] L☉
Temperature7,932±62[3] K
Metallicity [Fe/H]−0.04±0.04[8] dex
Rotational velocity (v sin i)154[9] km/s
Age0.8 Gyr[3]
0.5[10] Gyr
Other designations
λ Gem, 54 Geminorum, NSV 3512, BD+16 1443, FK5 277, HD 56537, HIP 35350, HR 2763, SAO 96746, WDS J07181+1632A[11]
Database references
SIMBADdata

Lambda Geminorum, Latinized from λ Geminorum, is a candidate multiple star system in the constellation Gemini. It is visible to the naked eye at night with a combined apparent visual magnitude of 3.57.[2] The distance to this system is 101 light years based on parallax,[6] and it is drifting closer with a radial velocity of –7.4 km/s.[5] It is a member of what is suspected to be a trailing tidal tail of the Hyades Stream.[12]

Components A and B of this system form a wide binary.[13] The secondary, component B, is a magnitude 10.7 stellar companion at an angular separation of 9.29″ from the primary along a position angle of 35.72°, as of 2009. The primary was identified as a spectroscopic binary by E. B. Frost in 1924.[14] This companion was confirmed during a lunar occultation with a separation of 14.1±0.7 mas and magnitude 6.8.[15]

The primary, designated component A, typically has been assigned a stellar classification of A3V,[3] which indicates this is an A-type main-sequence star that generates energy from core hydrogen fusion. However, in 1970 D. C. Barry classed it as A4IV,[16] suggesting this may be a subgiant star that has begun evolving into a giant star. It was catalogued a suspected variable star, but is now confirmed as constant.[4]

This star is less than a billion years in age with a rapid spin, showing a projected rotational velocity of 154 km/s[9] It is larger and hotter than the Sun, with twice the Sun's mass and 2.8 times the radius of the Sun. The star is radiating 27 times the Sun's luminosity from its photosphere at an effective temperature of 7,932 K.[3]

The primary displays a significant infrared excess in the K-band, which indicates an orbiting circumstellar disk of dust. A model fit to the data shows an inner radius between 0.08 AU and 0.14 AU, and an outer radius of up to 0.65 AU.[10]

  1. ^ a b Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference sps1966 was invoked but never defined (see the help page).
  3. ^ a b c d e f g h Cite error: The named reference Boyajian2013 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference magnitude was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference al32_11_759 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference AAA474_2_653 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Cheng_et_al_2016 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference aaa463_2_671 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Kirchschlager_et_al_2017 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Röser_et_al_2019 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Rodriguez_et_al_2015 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Frost1924 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Richichi1999 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Barry1970 was invoked but never defined (see the help page).