Vega

:This article is about Vega, the star. For other uses: see Vega (disambiguation)

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Vega (α Lyr / α Lyrae / Alpha Lyrae) is the brightest star in the constellation Lyra, and the fifth brightest star in the sky. It is the second brightest star in the Northern night sky, after Arcturus, and can often be seen near the zenith in the mid-northern latitudes during the Northern Hemisphere summer.

Related Topics:
Alpha - Star - Constellation - Lyra - Fifth brightest star - Arcturus - Zenith - Latitude - Northern Hemisphere - Summer

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

It is a "nearby star" at only 25.3 light years distance, and together with Arcturus and Sirius, one of the brightest stars in the Sun's neighbourhood.

Related Topics:
Light year - Arcturus - Sirius - Sun

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Vega is a vertex of the Summer Triangle, which consists of Vega (in Lyra), Deneb (in Cygnus) and Altair (in Aquila). This triangle is very recognisable in the northern skies for there are few bright stars in its vicinity.

Related Topics:
Vertex - Summer Triangle - Deneb - Cygnus - Altair - Aquila

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Its spectral class is A0V (Sirius, an A1V, is slightly less powerful) and it is firmly in the main sequence, fusing hydrogen to helium in its core. Since more powerful stars use their fusion fuel more quickly than smaller ones, Vega's life time is only one billion years, a tenth of our Sun's. Vega is two and a half times more massive than our Sun and burns at fifty times the power.

Related Topics:
Spectral class - Main sequence - Fusing - Hydrogen - Helium

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

In about AD 14,000, Vega will become the North Star, owing to the precession of the equinoxes. See Polaris for more information.

Related Topics:
AD - North Star - Precession - Equinox - Polaris

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Professional astronomers have used Vega for the calibration of absolute photometric brightness scales. When the magnitude scale was fixed, Vega happened to be close to zero magnitude. Therefore the visual magnitude of Vega was decided to be, by definition, zero at all wavelengths (this is no longer the case, as apparent magnitude is now most commonly defined in terms of the flux from the star). It also has a relatively flat electromagnetic spectrum in the visual region (wavelength range 350-850 nanometers, most of which can be seen with the human eye), so the flux densities are roughly equal, 2000-4000 Jy. The flux density of Vega drops rapidly in the infrared, and is near 100 Jy at 5 micrometres.

Related Topics:
Astronomer - Photometric - Visual magnitude - Electromagnetic spectrum - Jy - Infrared - Micrometre

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The name Vega comes from the Arabic word waqi meaning "falling", via the phrase نسر الواقع an-nasr al-wāqi?, translated "the swooping vulture". As part of the constellation Lyra it represents a jewel set in the body of the harp.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~