5 Lacertae
{{Short description|Star in the constellation Lacerta}}
{{Starbox begin}}
{{Starbox image
| image=
{{Location mark
|image=Lacerta constellation map.svg|alt=|float=center|width=220
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=5 Lacertae
|x=498|y=654
}}
|caption=Location of 5 Lacertae (circled)
}}
{{Starbox observe
| epoch = J2000
| constell = Lacerta
}}
{{Starbox character
| variable = LC
}}
{{Starbox astrometry
| prop_mo_ra = {{val|−2.554}}
| prop_mo_dec = {{val|−5.372}}
| parallax = 1.4838
| p_error = 0.1383
| dist_pc = {{val|665|62|54}}
| dist_ly = {{val|2170|200|180|fmt=commas}}
}}
{{Starbox orbit
| period = {{val|41.95|0.20}}
| eccentricity = {{val|0.49|0.01}}
| periastron = {{val|2427578.3|260|u=JD}}
| periarg = {{val|323|5.0}}
| k1 = {{val|12.2|1.2}}
| k2 = {{val|112.0|8.2}}
}}
{{Starbox detail
| source =
| component1 = 5 Lacertae A
| luminosity = 25,100{{efn|1=10^4.4 = 25118.86}}
| gravity =
| temperature = 3,790{{efn|1=10^3.57863921 = 3,790}}
| metal_fe =
| rotation =
| component2 = 5 Lacertae B
| mass2 =
| radius2 =
| luminosity2 =
| luminosity_bolometric2 =
| luminosity_visual2 =
| gravity2 =
| temperature2 =
| metal2_fe =
| rotation2 =
| age_gyr2 =
}}
{{Starbox catalog
| names = {{odlist | V=V412 Lac | BD=+46°3719 | FK5=3799 | HD=213310/1 | HIP=111022 | HR=8572 | SAO=52055 }}
}}
{{Starbox reference
| Simbad = HD+213310
}}
{{Starbox end}}
5 Lacertae (5 Lac) is a spectroscopic binary in the constellation Lacerta. Its apparent magnitude is 4.36.
Variability
File:V412LacLightCurve.png for V412 Lacertae, plotted from Hipparcos data]]
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. It was given the variable star designation V412 Lacertae in 1999 in a special name-list dedicated to variables detected from Hipparcos.
Characteristics
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.
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.
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Notes
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References
{{reflist|refs=
{{cite DR3|1986628812013105152}}
{{cite simbad | title=5 Lacertae | access-date=2018-03-26 }}
}}
{{Stars of Lacerta}}
{{DEFAULTSORT:5 Lacertae}}
Category:B-type main-sequence stars
Category:Slow irregular variables
Category:Spectroscopic binaries