- Delta² Lyrae
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Delta2 Lyrae[1] Observation data
Epoch J2000.0 Equinox J2000.0Constellation Lyra Right ascension 18h 54m 30.2838s Declination +36° 53' 55.007" Apparent magnitude (V) 4.30 Characteristics Spectral type M4II U−B color index +1.65 B−V color index +1.67 Astrometry Radial velocity (Rv) -26.4 km/s Proper motion (μ) RA: -6.73 mas/yr
Dec.: 3.26 mas/yrParallax (π) 3.63 ± 0.56 mas Distance approx. 900 ly
(approx. 280 pc)Details Mass 7 M☉ Radius 275 R☉ Luminosity 6,500 L☉ Other designations Delta2 Lyrae (δ2 Lyr) is a 4th magnitude star in the constellation Lyra, approximately 900 light years away from Earth. It is a class M4II star, meaning it is a bright giant star with a surface temperature under 3,500 kelvins. It shines with the light of 6,500 Suns, and has a radius of 200 solar radii, or 0.95 times the radius of Earth's orbit, though other measurements give an even larger radius of 1.3 astronomical units.[2]
It began life 75 million years ago as a bluish white B3 spectral type star of six solar masses, with a surface temperature between 11,000 and 25,000 kelvins. It now possesses a dead helium core, and is becoming an even larger giant. It is a semi-regular variable star that has its brightness change by 0.2 magnitudes over an ill-defined period. Delta2 Lyrae was once thought to form a visual binary with the star Delta1 Lyrae, but it does not, only appearing to do so to the naked eye.[2]
The spectral type of the nearby star system CCDM J18545+3654BC suggests that they are at the same distance as Delta2 Lyrae, which could mean that the three stars form a trinary star system. In this case, CCDM J18545+3654BC would be 24,000 AU away from Delta2 Lyrae, and it would take 24,000 years for it to make an orbit. The two stars in the CCDM J18545+3654BC system take at least 10,500 years to make an orbit and are separated by 600AU.[2]
References
- ^ "Simbad Query Result". Simbad. http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=*+12+Lyr&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id. Retrieved October 15, 2007.
- ^ a b c "Simbad Query Result". Simbad. http://www.astro.uiuc.edu/~kaler/sow/delta2lyr.html. Retrieved October 15, 2007.
Bayer α (Vega) • β (Sheliak) • γ (Sulafat) • δ¹ • δ² • ε¹, ² (Double Double) • ζ¹ • ζ² • η (Aladfar) • θ • ι • κ • λ • μ (Alathfar) • ν¹ • ν²Flamsteed 1 (κ) • 2 (μ, Alathfar) • 3 (α, Vega) • 4 (ε¹, Double Double) • 5 (ε², Double Double) • 6 (ζ¹) • 7 (ζ²) • 8 (ν¹) • 9 (ν²) • 10 (β, Sheliak) • 11 (δ¹) • 12 (δ²) • 13 • 14 (γ, Sulafat) • 15 (λ) • 16 • 17 • 18 (ι) • 19 • 20 (η, Aladfar) • 21 (θ)Nearby 2MASS 1835+3259 • α (Vega) • GJ 4063 • Gliese 747 • WISE 1828+2650Categories:- Lyra constellation
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