The bright star that marks the tail of the swan is big, bright, and heavy. If you want to know how big, bright, and heavy, well, the most precise answer we can give you is “very.”
We know for sure that Deneb is one of the more imposing stars around. But the details are a little hazy because the star’s distance is hazy. In part, that’s because of Deneb’s impressiveness.
The most accurate stellar distances come from Gaia, a space telescope. But Deneb is so bright that Gaia can’t look at it directly. Instead, it has to study the star indirectly – sort of like checking something out through the corner of its eye. It takes a lot of work to translate those glimpses into solid numbers.
In addition, the star’s outer layers are puffy and unstable, so it’s hard to know just where its surface is. And you need a good idea of the surface to measure the star’s location.
The best estimates say that Deneb is about 1500 light-years away – one of the most remote stars that’s visible to the eye alone. But other estimates say it’s almost twice that far. So based on that range, Deneb is about 15 to 20 times the mass of the Sun, 100 to 200 times the Sun’s diameter, and 50 thousand to 200 thousand times its brightness – impressive numbers for a very impressive star.
Deneb is a third of the way up the northeastern sky at nightfall, and soars high overhead during the night.
Script by Damond Benningfield