by Ann » Wed May 06, 2015 2:33 pm
I like the Summer Triangle. The three bright stars, Vega, Altair and Deneb, all belong to spectral class A and look so alike, and yet they are so dissimilar. First magnitude Altair, the second brightest-looking one of the stars at the end points of the Summer Triangle, is a modest star for its spectral class, only eleven times brighter than the Sun. Vega, the brightest-looking one and the (seemingly) bluest of the three, is almost fifty times brighter than the Sun and is seen pole on from the Earth, which means that we see deeper into its hot interior, making it look bluer. Distant Deneb, seemingly the puniest of them, is a true supergiant about fifty thousand times brighter than the Sun, with a radius about a hundred times that of the Sun. So if Deneb was to magically replace the Sun at the center of the solar system (thankfully, that is impossible), this white-hot supergiant would reach half-way from the center of the solar system to the Earth. Imagine!
Today's APOD is a very nice picture!
Ann
I like the Summer Triangle. The three bright stars, Vega, Altair and Deneb, all belong to spectral class A and look so alike, and yet they are so dissimilar. First magnitude Altair, the second brightest-looking one of the stars at the end points of the Summer Triangle, is a modest star for its spectral class, only eleven times brighter than the Sun. Vega, the brightest-looking one and the (seemingly) bluest of the three, is almost fifty times brighter than the Sun and is seen pole on from the Earth, which means that we see deeper into its hot interior, making it look bluer. Distant Deneb, seemingly the puniest of them, is a true supergiant about fifty [i]thousand[/i] times brighter than the Sun, with a radius about a hundred times that of the Sun. So if Deneb was to magically replace the Sun at the center of the solar system (thankfully, that is impossible), this white-hot supergiant would reach half-way from the center of the solar system to the Earth. Imagine!
Today's APOD is a very nice picture!
Ann