Human babies can scream and cry, but they’re not strong enough to tear down their own cot, let alone the nursery where they’re born. With baby stars, however, it’s different. Astronomers have discovered a stellar nursery that’s partly blown apart by its new inhabitants. Apparently, the birth of a star can be a very explosive event.
Stars are usually born in groups, deep within clouds of gas and dust. They swarm around each other like bees in a hive. Because they’re so close together, they cannot always avoid near-misses, or actual collisions. And when two newborn stars smash into each other, all hell breaks loose.
In the constellation Orion, the ALMA observatory has now imaged the result of such a stellar encounter. It must have happened some 500 years ago, in the 16th century. It looks like a spectacular firework display. But even the biggest fireworks on Earth are nothing compared to this cosmic blast.
Because of the stellar collision, part of the surrounding birth cloud is blown away into space. The ALMA image reveals long strands of gas and dust. They are about one light-year long, and they race through space at an incredible speed of 150 kilometers per second.
From the observations, astronomers have deduced that the explosion produced as much energy as the Sun emits in ten million years’ time. These are really powerful babies!
The results will tell astronomers more about the early stages of a star’s life. It may be that explosions like this one help to completely blow away the initial cloud of gas and dust from which the stars were born in the first place.
The explosion imaged by ALMA occurred in the Orion Molecular Cloud (OMC-1). OMC-1 is a giant region of cold gas and dust in the constellation Orion, at about 1,500 lightyears from Earth. It is one of the nearest giant star factories in our Milky Way galaxy. Normal, ‘optical’ telescopes can only see dark dust here, but with its millimeter-wave eyes, ALMA peers through the dust, to learn what’s going on deep inside the stellar nursery.
The powerful explosion in OMC-1 was studied in much detail by a group of astronomers, led by John Bally of the University of Colorado in Boulder. John is an expert on the birth of stars and planets. Earlier, he has studied this star forming region with other large telescopes, including the Gemini South telescope, which is also in Chile. For the ALMA observations, John worked together with colleagues from the United States, Mexico and Germany. The results were published in a professional magazine called The Astrophysical Journal