There's a new contender for the title of the Milky Way's brightest star.
The star had been discovered previously in the Peony nebula near the galaxy's dusty centre. But infrared observations taken from the ground and with NASA's Spitzer Space Telescope have pierced the dust to reveal just how bright the star is.
It boasts a wattage of about 3.2 million Suns. That is close to the output of Eta Carinae, the current record holder, which shines with the light of about 4.7 million Suns. However, measuring stellar brightness is not an exact science, and the stars may actually radiate similar amounts of light.
"As we get better measurements, these things change around a bit," says Michelle Thaller at NASA's Jet Propulsion Laboratory in California, who was not involved in the study.
It's possible that the galaxy's brightest star has not even been discovered yet. "There are probably other stars just as bright if not brighter in our galaxy that remain hidden from view," says team leader Lidia Oskinova of Potsdam University in Germany.
Both Eta Carinae and the Peony nebula star are evolved blue giants known as "Wolf-Rayet" stars, which have masses of 100 to 200 Suns. Either could self-destruct as a supernova at any moment.
The Peony nebula star lies about 26,000 light years away and Eta Carinae about 7500 light years away. "For all we know, they may have already blown themselves up and we're just waiting for the light to get to us to tell us that," Thaller told New Scientist.
For Thaller and other astronomers, knowing which blue giant is the brightest is less important than understanding what role the massive stars play in galactic evolution.
"These are real drivers of a galaxy's life cycle," Thaller says. "When these things go off, they will probably kick off a new generation of stars."