ALMA Helps Astronomers get Better View of the Birth of a Rare, Massive Star

Astronomers are witnessing the birth of a massive star in the Milky Way, The European Space Agency said. The monster star is taking form in the cosmic womb with over 500 times the mass of the Sun. According to the astronomers, just one in every 10,000 stars in Milky Way reach this kind of mass, making its formation a rare event.

The star, ESA said, is still growing out of a dark cloud and is feeding off of everything that's in its vicinity. The star is expected to be about 100 times larger than the Sun when it's finally born.

The rare event was studied by astronomers using Atacama Large Millimeter/submillimeter array (ALMA). They now have a kind of "prenatal scan" of the massive star located in a cloud called Spitzer Dark Cloud (SDC) 335.579-0.292, which is about 11,000 light years away from the Earth.

How stars form, is a widely studied subject. According to NASA, stars are born within clouds of dust. Turbulence within these clouds leads to knot formations that have enough gas and dust to collapse under its own gravitational pull. As the materials begin to collapse, the gas and dust within the clouds begins to heat-up. This hot core later becomes a star.

Stars of the size of Sun are extremely common in the galaxy. However, the one discovered now, a massive star, is an extremely rare one. NASA says that there are only a handful of such stars in the Milky Way. These massive stars are called hypergiants and have surface temperatures of more than 30,000K. These stars, however, have a shorter lifespan.

How massive stars originate is yet unknown. According to one theory, some dark cloud materials create several cores that eventually collapse under their gravitational attraction and form the star. The other theory, similar to average star births, is where dust and gas rush in the central core to make a giant star.

SDC335.579-0.292- the giant, dark cloud was first discovered by NASA's Spitzer Space Telescope and ESA's Herschel Space Observatory. Now, astronomers using ALMA have found finer aspects of the massive star formation.

The team has found the largest protostellar core ever found in the Milky Way. This core is the womb of the embryonic star and has 500 times greater mass than the Sun. Their observations showed that more dust and gas is being gobbled by the embryonic star. Note that the star formation region is making several stars and the core detailed in this report being just one of them.

"Even though we already believed that the region was a good candidate for being a massive star-forming cloud, we were not expecting to find such a massive embryonic star at its centre," Nicolas Peretto of CEA/AIM Paris-Saclay, France, and Cardiff University, UK. This object is expected to form a star that is up to 100 times more massive than the Sun. Only about one in ten thousand of all the stars in the Milky Way reach that kind of mass!"

"Not only are these stars rare, but their birth is extremely rapid and their childhood is short, so finding such a massive object so early in its evolution is a spectacular result," added Gary Fuller from the University of Manchester, UK., one of the astronomers involved in the research, according to a press release. 

Read the research paper here.