Spirals, Gaps, and Cavities in Circumstellar Disks: Are We Watching Planets Forming in Action?
Ruobing Dong
Lawrence Berkeley National Lab

Planets, like the ones in our own solar system, form in circumstellar disks surrounding newly born stars. We are about to enter a golden age in the field of planet formation and circumstellar disks, thanks to a fleet of new instruments with unprecedented resolving power that have just come online in the past few years. At near-infrared wavelengths, technological advances in adaptive optics and the use of differential imaging techniques have enabled us to achieve angular resolutions of 0.05 arcsec and inner working angles of 0.1 arcsec. At mm wavelengths, the Atacama Large Millimeter Array (ALMA) has brought us over one order of magnitude improvement over existing facilities in both resolution and sensitivity. Now for the first time in history, we are able to directly detect signals from planet formation activities on a solar system scale in nearby disks. Recent observations using the most powerful telescopes on Earth, such as Subaru, VLT, Gemini, and ALMA, have revealed exciting fine structures, such as spiral arms, gaps, and cavities, in many gaseous circumstellar disks. These structures have been widely speculated to be related to ongoing planet formation, though the mechanisms are currently in hot debate. In my talk I will review the major discoveries in observations of disks made in the past few years, and discuss their possible origins; particularly, whether they are induced by embedded planets currently forming in these disks. Lastly, I will picture my vision of the field in the coming decades; specifically, what are the questions that should be and will be addressed by the current and next generations of instruments, and what am I going to do to answer these questions.

Date:	Mercredi, 17 février 2016
Time:	11:00
Where:	Université de Montréal
	Pavillon Roger-Gaudry, local D-225
Contact:	Richard Leonelli