Iota Lyrae

ι Lyrae, Latinised as Iota Lyrae, is a binary star^[3] in the northern constellation of Lyra. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude that fluctuates around 5.22.^[3] This object is located approximately 910 light years distant from the Sun based on parallax, but is drifting nearer with a radial velocity of −26 km/s.^[6]

Iota Lyrae

A light curve for Iota Lyrae, plotted from TESS data[1]
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Lyra
Right ascension	19h 07m 18.13251s[2]
Declination	+36° 06′ 00.5592″[2]
Apparent magnitude (V)	5.22[3]
Characteristics
Spectral type	B6IV[4]
Variable type	Be star[5]
Astrometry
Radial velocity (Rv)	−26.0±4.6[6] km/s
Proper motion (μ)	RA: −1.437[2] mas/yr Dec.: −3.876[2] mas/yr
Parallax (π)	3.5858±0.1924 mas[2]
Distance	910 ± 50 ly (280 ± 10 pc)
Absolute magnitude (MV)	−1.94[7]
Orbit[8]
Period (P)	216.93 yr
Semi-major axis (a)	0.172″
Eccentricity (e)	0.637
Inclination (i)	145.5°
Longitude of the node (Ω)	171.4°
Periastron epoch (T)	B 1997.28
Argument of periastron (ω) (secondary)	201.2°
Details
Mass	5.2[9] M☉
Radius	6.7[10] R☉
Luminosity	854[10] L☉
Surface gravity (log g)	3.54[9] cgs
Temperature	12,059[10] K
Metallicity [Fe/H]	−0.11[9] dex
Rotational velocity (v sin i)	224[11] km/s
Age	168[12] Myr
Other designations
ι Lyr, 18 Lyr, BD+35°3485, GC 26338, HD 178475, HIP 93903, HR 7262, SAO 67834, WDS 19073+3606, GSC 02652-01709[13]
Database references
SIMBAD	data

This is a wide binary system with a computed orbital period of 217 years and an eccentricity of 0.6.^[8] The primary component has a stellar classification of B6IV,^[4] matching a B-type subgiant star. It is a Be star,^[14] displaying emission lines in its spectrum, and is spinning rapidly with a projected rotational velocity of 224 km/s.^[11] The star ranges in brightness from magnitude 5.20 down to 5.27.^[5] It has about five times the mass of the Sun and is radiating 854 times the Sun's luminosity from its photosphere at an effective temperature of 12,059 K.