Category Archives: Travel

University of Virginia


Last week I visited Jennifer Sobeck and my former Yale-colleague Nitya Kallivayalil at the University of Virginia. Jen is the deputy project manager of APOGEE-2, which is a large spectroscopic survey collecting 300,000 high-resolution spectra of Milky Way stars (and other bright targets). Hence, her head is full of stellar atmospheres and element abundances. Nitya is the go-to person for proper motions of Galactic satellites, which is why there’s tons of overlap between my work and both of theirs. Frequently distracted by great food and stunning weather, we scienced around for a few days. Our brainstorming for low hanging fruits in the APOGEE-2 dataset brought us a few great ideas, which we will hopefully pursue within the next weeks and months. Steve Majewski, PI of APOGEE and also based at UVa, outsourced the same task to all his undergrads. Let’s see who’s first to have some results!

Hubble Fellows Symposium 2016


It was great to visit Baltimore one last time and see the other fellows again. Baltimore has become a major hub for astronomy, even more so since STScI started hiring for JWST and WFIRST. All my friends from Yale seem to live in Baltimore now!

Chaos in the Galaxy

N-body simulations of tidal streams formed by Galactic satellites on regular orbits (A & B), a weakly chaotic orbit (C), and a strongly chaotic (D). The orbits of the four satellites are quite similar in terms of eccentricity and apo/pericenters, but the resulting streams show (and amplify) the underlying chaos.

During Adrian Price-Whelan’s dissertation talk today at the winter meeting (AAS227) of the American Astronomical Society in Kissimmee, Florida,  I was reminded that I haven’t mentioned our publication here. Adrian went through a whole lot of effort and characterized regular and chaotic orbits in a typical galactic gravitational potential. Usually, orbits in such a potential can be broadly categorized into chaotic and non-chaotic orbits. Adrian looked at this distinction in terms of the streams that are formed by satellites on such orbits. Continue reading Chaos in the Galaxy

Stream Meeting Ringberg Castle

It’s been a while since I’ve found the time to give an update on my activities. The reason is that there are just too many these days! Let me start catching up by telling you about an amazing workshop that took place from July 19-24 in Germany.


Jo Bovy (CITA) and Hans-Walter Rix (MPIA) organized a stream meeting at Ringberg Castle, which is a conference venue owned by the Max Planck Society. It’s not just called ‘castle’, it really is one! And the conference participants are literally locked up on a mountain, giving the meetings up there a very intimate and focussed atmosphere. I was put in the tower – but with a view like that (above) it didn’t occur to me to complain!  Continue reading Stream Meeting Ringberg Castle

Satellites and Streams in Santiago 2015


What a week! The ESO workshop ‘Satellites and Streams in Santiago’ is over now, and I am still amazed by how flawless this meeting was. As announced here a while ago, I’ve been organizing this conference with Steffen Mieske (ESO) for the last few months. In the end we were 107 registered participants plus some 10 guests. The line-up was absolutely amazing, ESO Director General Tim de Zeeuw gave an opening address, and we heard keynote presentations from the who-is-who in the fields of satellites (Jorge Peñarrubia, Michelle Collins, Pavel Kroupa, Rodrigo Ibata, Vasily Belokurov, Gurtina Besla), streams (Steven Majewski, Amina Helmi, Aaron Romanowski) and the star-cluster/dwarf-galaxy interface (Oleg Gnedin, Jay Strader, Dougal Mackey, Michael Hilker, Anil Seth).  Continue reading Satellites and Streams in Santiago 2015

Hubble Fellows Symposium 2015

2015 Hubble_Fellows_Symposium_GroupPhoto 2

Right after getting back from Chile I headed straight to Baltimore for this year’s Hubble Fellows Symposium at the Space Telescope Science Institute. Every year most of the 51 Hubble fellows (three years with each 17 fellows) get together at these meetings to present their work to each other. It is quite a fun meeting, since you get exciting updates on nearly all major fields of astronomy within three days. Last year we criticized, though, that the schedule left no time for chatting, schmoozing and collaborating. This year the organizers relaxed the schedule  a bit, so every talk was only 20 minutes long. It made the meeting much more enjoyable and put the fun back into the symposium.

MODEST15 in Concepción

One of my favorite conference series is “Modeling and Observing Dense Stellar Systems” (MODEST). This year, MODEST15 took me to Concepción in the beautiful south of Chile. Flying into Santiago over the Andes is already a spectacle.


But once landed in the south, the beauty of the landscape is breathtaking, and a few hours drive brings you to the most amazing places in the Andes, full of outdoor activities and gorgeous views.  Continue reading MODEST15 in Concepción