A team of astronomers has made use of the Atacama Large Millimeter/submillimeter Array (ALMA) to observe four distant stars, finding the best evidence yet of massive planets forming in the surrounding disk of dust and gas. The observations, which wouldn't have been possible without the instrument, have helped scientists to confirm an existing theory on planet formation.
While planets are born around almost every star, we still don't fully understand the processes by which they form. The European Southern Observatory's (ESO) ALMA telescope offers unparalleled sensitivity and image sharpness, allowing astronomers to peer at the disks of material that swirl around distant young stars, picking out clues about planet birth that significant advance our understanding.
One particular mystery surrounds a particular class of disk, known as transitional disk. There's a notable lack of dust in the central region of these structures, which scientists theorize could be due to the effect of stellar winds and high levels of radiation, or the fingerprints of massive young planets moving through the material.
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The ESO team used ALMA to map the distribution of dust and gas within four transitional disks, findings that while there is a significant drop in dust levels in the observed gaps, plenty of gas is present. That said, a gap in the gas distribution does also exist – some three times smaller than the dust gap.
While previous observations have left astronomers with no clear indication of which of the two theories is correct, the new data clearly points to the presence of huge planets with masses several times that of Jupiter, sweeping through the material, creating vast channels in the disks.
Impressively, the observations were made before ALMA was fully operational, and make use of just one tenth of the installation's power. Further observations will now be made to confirm that the finding in a larger sample of transitional disks. Looking even further forward, future instruments will surpass even ALMA's impressive abilities, boasting the capabilities to delve even deeper into the make-up of such distant objects.
"Direct planetary detection is just within reach of current instruments, and the next generation telescope currently under construction, such as the European Extremely Large Telescope, will be able to go much further," says team lead Nienke van der Marel of the Leiden Observatory in the Netherlands. "ALMA is pointing out where they will need to look."
The findings of the research were published in the journal Astronomy & Astrophysics.