Visiting SUNY Albany

I was visiting the State University of New York at Albany to meet up with my Masters thesis supervisor, Kevin Knuth and to present the physics colloquium. Had a great time and lots of nice discussions during the day and also in the evening at the Pump Station (highly recommended!).

Recent papers, Episode 5

image credit: ALMA/Calcada

It's a trap!

Recently, I was involved in two related papers:

Lopsided dust rings in transition disks
T. Birnstiel, C. P. Dullemond, P. Pinilla, A&A (2013) vol. 550, L8

A Major Asymmetric Dust Trap in a Transition Disk
N. van der Marel et al. Science (2013) vol. 340, 1199-1202

In the first one, we proposed that the rings seen in transition disks can easily become asymmetric: only a small asymmetry of the gas bump is enough to trigger a strong accumulation of dust particles.

Right around the time we were finishing up this paper, we were contacted by some colleagues who had just gotten their latest data from the ALMA observatory. They wanted to investigate the gas structure of the disk, but then they found a much more interesting and surprising feature in the dust which they had not expected: instead of a symmetric dust ring, they saw an extremely asymmetric structure, just like we predicted. We joined them in interpreting the data and the paper was published in the journal Science.

You can read more about it in the press releases from NRAO or ESO, or in German from the University of Heidelberg. It was also covered in an ESOCast - the video can be found here.

Recent papers, Episode 4

Forming the building blocks of planets by winning the lottery

A summary of the following nice paper by Fredrik was long overdue:

Breaking through: The effects of a velocity distribution on barriers to dust growth
F. Windmark, T. Birnstiel, C. W. Ormel, and C. P. Dullemond, A&A (2012) vol. 544, L16

In these two papers, we show how the building blocks of planets can be formed by mutual sticking instead of gravitational attraction, in contrast to recent beliefs. The short explanation is that we include two key effects, one is based on recent laboratory results (see also this post), the other one involves randomness, such that a few "lucky" particles can continue to grow, even in a generally hostile environment.

However with this review, I'm really lazy and instead of explaining the details here, I let the first author speak for himself, so head over to Fredriks blog, to read how we solved these problems.