Theta Lyrae

Theta Lyrae
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Lyra
Right ascension	19h 16m 22.0951s / 19h 16m 30.069s / 19h 16m 28.7s
Declination	+38° 8' 1.431" / +38° 8' 35.80" / +38° 7' 1"
Apparent magnitude (V)	4.347 / 9.5 / 11.0
Characteristics
Spectral type	K0II + K2III + ?
U−B color index	+1.23[citation needed]
B−V color index	+1.25[citation needed]
Astrometry
Radial velocity (Rv)	−31.05±0.14 km/s
Proper motion (μ)	RA: −2.864 mas/yr ; Dec.: 4.114 mas/yr
Parallax (π)	4.2005 ± 0.1053 mas
Distance	755.6+21.8; −20.2 ly ; (237.9+6.7; −6.2 pc)
Absolute magnitude (MV)	−2.76+0.27; −0.24
Details
θ Lyr
Radius	60.31+1.92; −2.99 R☉
Luminosity	1,374±43 L☉
Surface gravity (log g)	1.93 cgs
Temperature	4,523±44 K
Metallicity [Fe/H]	−0.01 dex
Rotational velocity (v sin i)	3.6±1.4 km/s
Other designations
	θ Lyrae, 21 Lyrae, HR 7314, BD+37°3398, HD 180809, SAO 68065, HIP 94713, GC 26585, IDS 19129+3757, GSC 03121-02287, BD +37°3399, BD +37°3399B
Database references
SIMBAD	data

Theta Lyrae (θ Lyr) is a star in a trinary star system, in the constellation Lyra, approximately 760 light years away from Earth. Theta Lyrae is an orange bright giant star of the spectral type K0II, which means that it possesses a surface temperature of about 5,000 K, and is many times bigger and brighter, yet cooler, than the Sun.

It is orbited by a subsystem composed of BD+37° 3399 and BD+37° 3399B. 10th magnitude BD+37° 3399 is a giant star with a spectral type of K2III. It is therefore almost the same temperature as Theta Lyrae, but smaller and dimmer.^[6] BD+37° 3399B is an 11th magnitude star of an unknown spectral type.^[7]

References

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[2]

[3]

[4]

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[7]

Observation data Epoch J2000.0 Equinox J2000.0
Constellation	Lyra
Right ascension	19h 16m 22.0951s / 19h 16m 30.069s / 19h 16m 28.7s
Declination	+38° 8' 1.431" / +38° 8' 35.80" / +38° 7' 1"
Apparent magnitude (V)	4.347 / 9.5 / 11.0
Characteristics
Spectral type	K0II^[1] + K2III + ?
U−B color index	+1.23^{[citation needed]}
B−V color index	+1.25^{[citation needed]}
Astrometry

Radial velocity (R_v)	−31.05±0.14^[2] km/s
Proper motion (μ)	RA: −2.864 mas/yr^[2] Dec.: 4.114 mas/yr^[2]
Parallax (π)	4.2005 ± 0.1053 mas^[2]
Distance	755.6+21.8 −20.2 ly (237.9+6.7 −6.2 pc)^[3]
Absolute magnitude (M_V)	−2.76+0.27 −0.24^[1]

Details
θ Lyr
Radius	60.31+1.92 −2.99^[4] `R`_☉
Luminosity	1,374±43^[4] `L`_☉
Surface gravity (log g)	1.93^[1] cgs
Temperature	4,523±44^[4] K
Metallicity [Fe/H]	−0.01^[1] dex
Rotational velocity (v sin i)	3.6±1.4^[1] km/s

Other designations
θ Lyrae, 21 Lyrae, HR 7314, BD+37°3398, HD 180809, SAO 68065, HIP 94713, GC 26585, IDS 19129+3757, GSC 03121-02287, BD +37°3399, BD +37°3399B^[5]^[6]^[7]
Database references
SIMBAD	data