Astronomers have discovered a hefty star near the Galaxy’s center. The star shines with an incredible wattage of over 3 million times the luminosity of the Sun, making this star the second brightest star in our Galaxy. The brightest known star in our Galaxy is Eta Carinae, with a luminosity of approximately 5 million times the solar luminosity.

The new stellar giant is dubbed the "Peony nebula star". It was spotted by NASA's Spitzer Space Telescope (SST) and other ground-based telescopes. However, astronomers say it is difficult to estimate an exact luminosity for these blazing stars, so they could potentially shine with similar light outputs.

"The Peony nebula star is a fascinating creature. It appears to be the second-brightest star that we now know of in the Galaxy, and it's located deep into the Galaxy's center," said Lidia Oskinova of Potsdam University in Germany. "There are probably other stars just as bright if not brighter in our Galaxy that remain hidden from view." Oskinova is principal investigator for the study.

Scientists already knew about the Peony nebula star, but as it is located in the dusty core of our Galaxy, its extreme wattage was not revealed until now. Spitzer's dust-penetrating infrared detectors can peer into the heart of the Galaxy, into regions obscured for optical light instruments. Similarly, infrared data from the European Southern Observatory's New Technology Telescope in Chile were complimentary in determining the Peony nebula star's luminosity.

"Infrared astronomy opens extraordinary views into the environment of the central region of our Galaxy," said Oskinova.

The brightest stars in the Universe are also the largest. Astronomers estimate the Peony nebula star started its evolution with a hefty mass of roughly 150 to 200 times that of the Sun. Such cosmic behemoths rare and puzzle astronomers because they push the limits required for stars to form. Theory predicts that if a star starts out too massive, it will disintegrate into two or more stars.

The Peony nebula star is a type of giant blue stars known a Wolf-Rayet star, with a diameter roughly 100 times the solar diameter. Therefore, if this star were placed in the Sun’s position, it would extend out to about the orbit of Mercury.

With an enormous mass, the Peony nebula star sheds a prodigious amount of material as strong winds over its relatively short lifetime of a few million years. This material is pushed so hard by strong radiation from the star that the winds speed up to about 1.6 million km per hr in only a few hours.

Ultimately, the Peony nebula star will blow up in a tremendous explosion known as supernova. Actually, Oskinova and her colleagues believe that the star is prone for exploding soon, which in astronomical terms mean anytime within a few millions of years from now.

"When this star blows up, it will evaporate any planets orbiting stars in the vicinity," said Oskinova. "Farther out from the star, the explosion could actually trigger the birth of new stars."

In addition to the star itself, the astronomers noted a cloud of dust and gas, termed a nebula, around the star. The team nicknamed this cloud the Peony nebula because it resembles the ornate flower.

"The nebula was probably created from the spray of dust leaking off the massive Peony nebula star," said Andreas Barniske of Potsdam University, lead author of the study.

Further Reading

SST
http://www.spitzer.caltech.edu/

Aymen Mohamed Ibrahem
Senior Astronomy Specialist