Stars of a Summer's Triangle
Image Credit &
Copyright:
Rogelio Bernal
Andreo (Deep Sky Colors)
Rising at the start of a northern summer's night, these
three bright stars form the familiar asterism known as
the Summer Triangle.
Altair, Deneb, and Vega
are the alpha stars of their respective constellations, Aquila, Cygnus,
and Lyra, nestled near the Milky Way.
Close in apparent brightness the three do look similar in these
telescopic portraits,
but all have
their own
stellar stories.
Their similar appearance hides the fact that
the Summer Triangle stars actually span a large range in
intrinsic luminosity and distance.
A main sequence
dwarf star, Altair is some 10 times brighter
than the Sun and 17 light-years away, while
Vega, also a hydrogen-fusing dwarf, is around 30 times brighter than
the Sun and lies 25 light-years away.
Supergiant Deneb, at about 54,000 times the solar luminosity,
lies some 1,400 light-years distant.
Of course, with a whitish blue hue,
the stars of the Summer Triangle are all hotter than
the Sun.