Herschel discovers 15 new protostars in Orion

Astronomers from the Herschel Space Observatory have spotted 15 new protostars, surrounded in an envelope of dust and gas, in the constellation Orion near our Milky Way galaxy.

“Herschel has revealed the largest ensemble of such young stars in a single star-forming region. With these results, we are getting closer to witnessing the moment when a star begins to form,” said researcher Amelia Stutz, from the Max Planck Institute for Astronomy in Heidelberg, Germany.

Dense envelopes of gas and dust surround the fledging stars known as protostars, making their detection difficult.

The 15 newly observed protostars turned up by surprise in a survey of the biggest site of star formation near our solar system, located in the constellation Orion.

The discovery gives scientists a peek into one of the earliest and least understood phases of star formation.

Stars spring to life from the gravitational collapse of massive clouds of gas and dust. This change-over from stray, cool gas to the ball of super-hot plasma we call a star is relatively quick by cosmic standards, lasting only a few hundred thousand years.

Finding protostars in their earliest, most short-lived and dimmest stages poses a challenge.

Astronomers long had investigated the stellar nursery in the Orion Molecular Cloud Complex, a vast collection of star-forming clouds, but had not seen the newly identified protostars until Herschel observed the region.

“Previous studies have missed the densest, youngest and potentially most extreme and cold protostars in Orion,” said Stutz, lead author of the paper to be published in The Astrophysical Journal.

“These sources may be able to help us better understand how the process of star formation proceeds at the very earliest stages, when most of the stellar mass is built up and physical conditions are hardest to observe,” Stutz added.

Herschel spied the protostars in far-infrared, or long-wavelength, light, which can shine through the dense clouds around burgeoning stars that block out higher-energy, shorter wavelengths, including the light our eyes see.

Of the 15 newly discovered protostars, 11 possess very red colours, meaning their light output trends toward the low-energy end of the electromagnetic spectrum. This output indicates the stars are still embedded deeply in a gaseous envelope, meaning they are very young.

Observations from NASA’s Spitzer Space Telescope and the Atacama Pathfinder Experiment (APEX) telescope in Chile, a collaboration involving the Max Planck Institute for Radio Astronomy in Germany, the Onsala Space Observatory in Sweden, and the European Southern Observatory in Germany, contributed to the findings.

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