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Vega

HIP 91262; Alpha Lyr; 3 Lyr

DoubleStar Lyr Mag 0.03

Dados do Objeto

Designação do Catálogo
HIP 91262; Alpha Lyr; 3 Lyr
Tipo
DoubleStar
Constelação
Lyr
Magnitude
0.03
Ascensão Reta
18h 36m 56.3s
Declinação
+38° 47' 01.0"
Distância
25 anos-luz
HR
7001
HIP
91262
Bayer
Alpha
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Sobre Vega

Descrição

Vega is the fifth brightest star in the night sky at magnitude 0.03 and the brightest star in the constellation Lyra. It is a blue-white main-sequence star of spectral type A0V, located about 25 light-years from Earth. Vega is roughly 2.1 times the mass of the Sun, 40 times more luminous, and rotates extremely rapidly — once every 12.5 hours, which causes it to bulge significantly at its equator. An infrared excess detected by IRAS in 1983 revealed a circumstellar disk of dust, one of the first discovered around a main-sequence star.

Dicas de Observação

One of the most recognizable stars in the sky, Vega forms the brightest vertex of the Summer Triangle asterism along with Deneb and Altair. Its brilliant blue-white color is striking to the naked eye. Look nearby for the famous Ring Nebula (M57) and Epsilon Lyrae, the 'Double Double' — a pair of double stars that makes an excellent test of optical quality. Vega is circumpolar from latitudes north of 51°N. Best observed from May through November.

História

The name Vega derives from the Arabic 'al-Nasr al-Waqi' meaning 'the swooping eagle.' Around 12,000 BC, Vega was the North Star, and it will be again around AD 13,700 due to precession of Earth's axis. Vega was the first star (other than the Sun) to be photographed, captured by astronomers at Harvard on July 17, 1850. It was also one of the first stars to have its parallax measured by Friedrich Georg Wilhelm Struve in 1837.

Curiosidades

Vega served as the original standard for the photometric magnitude system — its magnitude was defined as exactly 0.00 (modern measurements give 0.03). It also serves as a calibration reference for photometric systems. Because of its rapid rotation, the temperature at Vega's poles is about 2,300 K hotter than at its equator.