Gamma Lyrae

Gamma Lyrae

Template:Location mark Location of γ Lyrae
Observation data Epoch J2000      Equinox J2000
Constellation	Lyra
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	3.24
Characteristics
Spectral type	B9 III
U−B Template:Engvar	−0.125
B−V Template:Engvar	−0.04
Astrometry
Radial velocity (Rv)	−21.1 km/s
Proper motion (μ)	RA: −3.09 mas/yr Dec.: +1.11 mas/yr
Parallax (π)	5.26±0.27 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−3.14
Details
Mass	Template:Val Template:Solar mass
Radius	Template:Val Template:Solar radius
Luminosity	Template:Val Template:Solar luminosity
Surface gravity (log g)	Template:Val cgs
Temperature	Template:Val K
Metallicity [Fe/H]	+0.15 dex
Rotational velocity (v sin i)	65 km/s
Age	Template:Val Myr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBAD	data

Gamma Lyrae, Latinised from γ Lyrae, and formally named Sulafat Template:IPAc-en, is the second-brightest star in the northern constellation of Lyra. With an apparent visual magnitude of 3.3, it is readily visible to the naked eye. Parallax measurements yield an estimated distance of Template:Convert from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of Template:Val due to interstellar dust.

Nomenclature

γ Lyrae (Latinised to Gamma Lyrae) is the star's Bayer designation.

It bore the traditional names Sulafat (Sulaphat), from the Arabic al-sulḥafāt "turtle", and Jugum, from the Latin "yoke". The connection with turtles is that fine harps were traditionally made of tortoiseshell. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Sulafat for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.

In Chinese astronomy, (), meaning Clepsydra Terrace, refers to an asterism consisting of this star, Delta² Lyrae, Beta Lyrae and Iota Lyrae. Consequently, the Chinese name for Gamma Lyrae itself is (, Template:Langx).

Properties

This is a giant star with a stellar classification of B9 III, indicating it has exhausted the supply of hydrogen at its core and evolved away from the main sequence. The effective temperature of the outer envelope of this star is Template:Val, giving it the blue-white hue typical of a B-type star. The interferometry-measured angular diameter of this star is Template:Val, which, at its estimated distance, equates to a physical radius of roughly 13 times the radius of the Sun.

In 1909, Canadian astronomer Samuel A. Mitchell identified this star as a spectroscopic binary, although he was unable to split the absorption lines of the components. He found that a period of 25.6 days matched his measurements. It was reported as a spectroscopic binary as recently as 2001, but is now believed to be a single star with a high rate of rotation for stars of this type.