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The Peony Nebula Star
As of July, 2008, what is called the Peony Nebula star officially became the second-brightest star in the Milky Way. Although astronomers have known about the existence of this star for a while, infrared light images from the Spitzer Space Telescope revealed new evidence. It was difficult to learn the brightness of the Peony Nebula star because it is shrouded by the dust from the Milky Way, but the infrared pictures made the star easier to study.
This star is located in the heart of our galaxy in the constellation Sagittarius. Its technical name is WR 102ka, with WR referring to its classification as a Wolf-Rayet star. Wolf-Rayet stars are highly unstable, very massive stars which quickly shed layers of energy due to a stellar wind. The Peony Nebula star is indeed massive: about 150 to 200 times more massive than our sun--it is also 100 times the diameter of the sun. Yet, the brighter and more massive the star, the quicker it burns out, thus leading to a spectacular death as a supernova. It is possible that the Peony Nebula star could explode in the next few million years--but that is not much in space time.
So, if the Peony Nebula star is the second-brightest star in our galaxy, what is the brightest? That would be Eta Carniae, located in the constellation Carina in the southern hemisphere. Eta Carinae is 7,500 light years away and 4.7 million times brighter than the sun, while the Peony Nebula star is 26,093 light years away and about 3.2 million times brighter than the sun. However, scientists cannot be sure that Eta Carniae is definitely brighter because there is so much dust preventing decent viewing of either star.
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