Iota Lyrae
Binary star in the constellation Lyra
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ι Lyrae, Latinised as Iota Lyrae, is a binary star[2] 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.[2] This object is located approximately 910 light years distant from the Sun based on parallax, but is drifting nearer with a radial velocity of â26 km/s.[5]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 07m 18.13251s[1] |
| Declination | +36° 06â² 00.5592â³[1] |
| Apparent magnitude (V) | 5.22[2] |
| Characteristics | |
| Spectral type | B6IV[3] |
| Variable type | Be star[4] |
| Astrometry | |
| Radial velocity (Rv) | â26.0±4.6[5] km/s |
| Proper motion (μ) | RA: â1.437[1] mas/yr Dec.: â3.876[1] mas/yr |
| Parallax (Ï) | 3.5858±0.1924 mas[1] |
| Distance | 910 ± 50 ly (280 ± 10 pc) |
| Absolute magnitude (MV) | â1.94[6] |
| Orbit[7] | |
| Period (P) | 216.93 yr |
| Semi-major axis (a) | 0.172â³ |
| Eccentricity (e) | 0.637 |
| Inclination (i) | 145.5° |
| Longitude of the node (Ω) | 171.4° |
| Periastron epoch (T) | B 1997.28 |
| Argument of periastron (Ï) (secondary) | 201.2° |
| Details | |
| Mass | 5.2[8] Mâ |
| Radius | 6.7[9] Râ |
| Luminosity | 854[9] Lâ |
| Surface gravity (log g) | 3.54[8] cgs |
| Temperature | 12,059[9] K |
| Metallicity [Fe/H] | â0.11[8] dex |
| Rotational velocity (v sin i) | 224[10] km/s |
| Age | 168[11] 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[12] | |
| Database references | |
| SIMBAD | data |
This is a wide binary system with a computed orbital period of 217 years and an eccentricity of 0.6.[7] The primary component has a stellar classification of B6IV,[3] 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.[10] The star ranges in brightness from magnitude 5.20 down to 5.27.[4] 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.