Vega, the Zero Star
Vega, the fifth brightest star in the sky, used in the past as a standard reference for the zero point on the magnitude scale, has an oblate shape, due to its high rotation speed. This and other data have been obtained from studies based on interferometry, a technique that allows reaching a very high angular resolution, combining the images acquired by several telescopes
Alfa Lyrae, the bright Vega, is 7.68 parsecs or 25 light-years away from the Solar System. Of a beautiful white color, it belongs to the spectral type A0 and is on the main sequence as the Sun. Visible from the northern hemisphere, it forms together with Deneb and Altair the so-called Summer Triangle, an asterism easy to spot with the naked eye even for the most inexperienced observers. Due to its brightness and color, Vega has been used for a long time as a standard reference in the scale of stellar magnitudes, that is, it was the star on which to calibrate the zero-point of the scale.
Known and admired since ancient times, it has been studied over the centuries with all possible instruments. However, the most important and surprising progress had only taken place in…
