ALMA reveals planetary construction sites around young stars

ALMA reveals planetary construction sites around young stars

European Southern Observatory Press Release

Posted on 20 December 2015 by Astronomy Now

Planets are found around nearly every star, but astronomers still do not fully understand how — and under what conditions — they form. To answer such questions, they study the rotating discs of gas and dust present around young stars from which planets are built. But these discs are small and far from Earth, and the power of the Atacama Large Millimetre/submillimetre Array (ALMA) in the Chilean Andes was needed for them to reveal their secrets.

A special class of discs, called transitional discs, have a surprising absence of dust in their centres, in the region around the star. Two main ideas have been put forward to explain these mysterious gaps. Firstly, the strong stellar winds and intense radiation could have blown away or destroyed the encircling material. Alternatively, massive young planets in the process of formation could have cleared the material as they orbit the star.

The unparalleled sensitivity and image sharpness of ALMA have now allowed the team of astronomers, led by Nienke van der Marel from the Leiden Observatory in the Netherlands to map the distribution of gas and dust in four of these transitional discs better than ever before. This in turn has allowed them to choose between the two options as the cause of the gaps for the first time.

The new images show that there are significant amounts of gas within the dust gaps. But to the team’s surprise, the gas also possessed a gap, up to three times smaller than that of the dust.

More:
http://astronomynow.com/2015/12/20/alma-reveals-planetary-construction-sites-around-young-stars/