The violent way that stars are born

Spectacular new images of a star cluster crowded with newborn stars and planets are teaching scientists about the origins of our own solar system.

Newborn stars in a cloud of gas and dust called RCW 38 in the constellation of Vela. Image credit: ESO
The stars in this image, just released by the European Southern Observatory, lie in a cloud of gas and dust called RCW 38 in the constellation of Vela, the sails.

The densely packed stars, 5,500 light-year away from us, are a curious mix. As the astronomers describe it, young, titanic stars are bombarding fledgling suns and planets with powerful winds and blazing light. They are helped in this devastating task by short-lived, massive stars that explode as supernovae.

This family of stars is known as an embedded cluster because of the nebulosity that is wrapped around it. It is thought that our own solar system was born in a similarly dramatic environment, although the clouds of gas and dust that once surrounded us have long been lost.

Most stars are thought to have formed in similar circumstances, so embedded clusters provide scientists with a natural laboratory in which they can study star and planetary formation.

Astronomers used a technique called adaptive optics to get sharp images of the star cluster using ESO’s Very Large Telescope in Chile. Kim DeRose, chief author of a new report in the Astronomical Journal, said: “By looking at star clusters like RCW 38, we can learn a great deal about the origins of our solar system and others, as well as those stars and planets that have yet to come.”

The scientists focused on a small area in the centre of the cluster surrounding a massive star labelled IRS2, which glows in the searing, white-blue range, the hottest surface color and temperatures possible for stars. These dramatic observations revealed that IRS2 is actually not one, but two scorching hot stars just 500 times as far apart as the Earth from the Sun.

They also found a handful of protostars – the faint precursors to fully formed stars – plus dozens of other candidate stars that have so-far survived despite an ultraviolet battering by IRS2, but not all of which will survive much longer.

IRS2’s strong radiation energizes and disperses the material that might otherwise collapse into new stars, or that has settled into so-called protoplanetary discs around developing stars. In the course of several million years, the surviving discs may give rise to the planets, moons and comets that make up planetary systems like our own.

As if intense ultraviolet rays were not enough, crowded stellar nurseries like RCW 38 also subject their brood to frequent supernovae, as giant stars explode at the ends of their lives. These explosions scatter material throughout nearby space, including rare isotopes – exotic forms of chemical elements that are created in these dying stars.

Similar isotopes have been detected in our own Sun, leading astronomers to conclude that the Sun formed in a cluster like RCW 38 rather than in a more peaceful part of the Milky Way.

A more famous cosmic cradle is the Orion Nebula, M42, which was photographed in amazing detail by NASA’s Huble and Spitzer space telescopes. In other regions of the sky, young solar systems have even been photographed.

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