5 Lacertae

5 Lacertae
Location of 5 Lacertae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Lacerta
Right ascension 22h 29m 31.823s[1]
Declination +47° 42′ 24.79″[1]
Apparent magnitude (V) 4.36[2]
Characteristics
Spectral type K6–M0I + B7/8V[3]
U−B color index +1.11[2]
B−V color index +1.68[2]
Variable type LC[4]
Astrometry
Radial velocity (Rv)−3.4±0.2[5] km/s
Proper motion (μ) RA: −2.554 mas/yr[6]
Dec.: −5.372 mas/yr[6]
Parallax (π)1.4838 ± 0.1383 mas[6]
Distance2,170+200
−180 ly
(665+62
−54 pc)[7]
Orbit[5]
Period (P)41.95±0.20 yr
Eccentricity (e)0.49±0.01
Periastron epoch (T)2427578.3±260 JD
Argument of periastron (ω)
(secondary)		323±5.0°
Semi-amplitude (K1)
(primary)		12.2±1.2 km/s
Semi-amplitude (K2)
(secondary)		112.0±8.2 km/s
Details
5 Lacertae A
Mass5.11±0.18[8] M☉
Radius359[9] R☉
Luminosity25,100[9][a] L☉
Temperature3,790[9][b] K
Rotational velocity (v sin i)50[10] km/s
Age110±10[8] Myr
5 Lacertae B
Rotational velocity (v sin i)89[2] km/s
Other designations
V412 Lac, BD+46° 3719, FK5 3799, HD 213310/1, HIP 111022, HR 8572, SAO 52055[11]
Database references
SIMBADdata
5 Lacertae in optical light

5 Lacertae (5 Lac) is a spectroscopic binary in the constellation Lacerta. Its apparent magnitude is 4.36.

A light curve for V412 Lacertae, plotted from Hipparcos data[12]

5 Lacertae is a slow irregular variable star with a small amplitude. Photometry from the Hipparcos satellite showed brightness changes between Hipparcos magnitudes 4.39 and 4.56 with no clear periodicity.[4] It was given the variable star designation V412 Lacertae in 1999 in a special name-list dedicated to variables detected from Hipparcos.[13]

The spectrum of 5 Lacertae clearly indicates both a hot component and a cooler component, recognised even in early spectra. Published spectral types for the brighter cool component vary from K4 to M0, with a luminosity class of giant or supergiant. The hotter star is generally classed as a relatively unevolved late B or early A star, but an automated classification program gave it a spectral class of B2V.[14]

Radial velocity variations in the absorption lines from the two separate stars have been measured to determine the orbit. This has an unusually long period of almost 42 years. The two stars have an eccentric orbit with a projected axis of about 15 au.[5]

  1. ^ a b Cite error: The named reference van Leeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference bsc was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference pantaleoni was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Hendry1978 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference DR3 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference b-j was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Baines2018 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Healy2023 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference vanbelle 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 HipDataAccess was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference ibvs was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference skiff was invoked but never defined (see the help page).


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