Vega

related topics
{math, energy, light}
{god, call, give}
{day, year, event}
{acid, form, water}
{area, part, region}
{group, member, jewish}
{line, north, south}
{country, population, people}
{rate, high, increase}
{language, word, form}
{island, water, area}
{car, race, vehicle}
{ship, engine, design}

Vega (α Lyr, α Lyrae, Alpha Lyrae) is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus. It is a relatively close star at only 25 light-years from Earth, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.

Vega has been extensively studied by astronomers, leading it to be termed "arguably the next most important star in the sky after the Sun."[8] Vega was the northern pole star around 12,000 BC and will be so again around AD 13,727 when the declination will be +86°14'.[9] Vega was the first star other than the Sun to be photographed and the first to have its spectrum recorded. It was one of the first stars whose distance was estimated through parallax measurements. Vega has served as the baseline for calibrating the photometric brightness scale, and was one of the stars used to define the mean values for the UBV photometric system.

Vega is only about a tenth of the age of the Sun, but since it is 2.1 times as massive its expected lifetime is also one tenth of that of the Sun; both stars are at present approaching the midpoint of their life expectancies. Vega has an unusually low abundance of the elements with a higher atomic number than that of helium.[5] Vega is also a suspected variable star that may vary slightly in magnitude in a periodic manner.[10] It is rotating rapidly with a velocity of 274 km/s at the equator. This is causing the equator to bulge outward because of centrifugal effects, and, as a result, there is a variation of temperature across the star's photosphere that reaches a maximum at the poles. From Earth, Vega is being observed from the direction of one of these poles.[11]

Based on an observed excess emission of infrared radiation, Vega appears to have a circumstellar disk of dust. This dust is likely to be the result of collisions between objects in an orbiting debris disk, which is analogous to the Kuiper belt in the Solar System.[12] Stars that display an infrared excess because of dust emission are termed Vega-like stars.[13] Irregularities in Vega's disk also suggest the presence of at least one planet, likely to be about the size of Jupiter,[14] in orbit around Vega.[15]

Full article ▸

related documents
Cygnus X-1
Bohr model
Light
Loop quantum gravity
Luminiferous aether
Momentum
Surface tension
Cosmic inflation
Photon
Andromeda Galaxy
Uncertainty principle
Open cluster
Orbit
Stellar classification
Binary star
Astronomy
History of astronomy
Time travel
Bernoulli's principle
Holography
Spacetime
Speed of light
Electricity
Physical cosmology
Dirac equation
Extrasolar planet
Lightning
Planet
Centripetal force
Vacuum