Tag Archives: work

Big in Japan

I get to be on Japanese television!! NHK, Japan’s national public broadcasting organization, asked me for an interview about the evolution of globular clusters and the formation of tidal streams. I’m still excited about it, it was so much fun!


NHK produces a show called Cosmic Front Next, which covers one aspect of astronomy per episode. Each episode is one hour long and features several scientists. Since 2011, they have aired about one episode per week. That’s a lot of astronomy! Surprisingly, they haven’t covered globular clusters yet. So, I’m more than happy that I get to be on this episode of Season 5. Continue reading Big in Japan


ISIMA 2014 Toronto

Lonely moose guarding the gate of the University of Toronto

I spent all of August in beautiful Canada at the University of Toronto for the International Summer Institute for Modeling in Astrophysics (ISIMA)Continue reading ISIMA 2014 Toronto



The grande finale of my Euro trip 2014 was the MODEST14 conference in Bad Honnef. MODEST, standing for Modeling and Observing Dense Stellar Systems, is a very specific conference series focussing on my prime field of study: stellar dynamics. The MODEST meetings are always my favorite get-togethers as you get to meet all your friends in this small community, and within a week you have a fresh and complete overview on the current state of the field. This specific edition of the conference series was organized by Sambaran Banerjee who works in the stellar dynamics group of Pavel Kroupa at the University of Bonn. Together with his scientific and local organizing committees he did an amazing job, turning the old mansion of the DFG Physikzentrum into a club house of a debating society. The conference picture above and many more were taken by Fabian Lüghausen. The next big MODEST meeting will be in Concepción, Chile, from March 2-6.

How Galaxies treat their Globular Clusters

After almost 2 years of development and testing, Michael Brockamp (University of Bonn) and I have finally published our MUESLI code for the simulation of globular star clusters orbiting in elliptical galaxies. Together with Holger Baumgardt from Brisbane (Australia), Ingo Thies, and Pavel Kroupa (both from the University of Bonn), we have put together a really exciting study of systems of globular clusters and how they erode over time in the gravitational field of their host galaxies.

This figure shows the number of globular star clusters at a given radius of the elliptical galaxy they were simulated in. The black line gives their initial distribution at the beginning of the simulations, the blue dashed line shows their distribution after just one billion years of evolution. As you can see, the distribution develops a core, as clusters in the center of the galaxy get destroyed more quickly. These cores are observed for giant elliptical galaxies, hence we suggest that they formed via ‘tidal erosion’, that is, the clusters in the center got disrupted by the galaxy.

Continue reading How Galaxies treat their Globular Clusters



Blue hour’s sweet light was looming over Riverside Church when I left the astronomy department yesterday. Meanwhile, New York was turning into a huge slush puppie as the temperatures got milder. I felt like I had earned myself an afterwork beer with fellow Columbia astronomers and visiting ex-Columbiast Taka Tanaka. After being super productive during the last weeks, my Palomar 5 project is finally coming to an end! All I have to do now is wait for Yeti to deliver results. No, I did not hire Jaroslav Haas to compute likelihoods for me. Yeti is Columbia’s new >1600 core supercomputer, which has been inaugurated end of last year. I’ll post some results as soon as I get them, which will be in about one week. I’m excited, it all looks very, very promising.



After a busy but very successful week, Alejandro and Mathieu took me out for a pre-weekend drink. We ended up in a place in their neighborhood in Harlem called “Bier International”, and it turned out to be a fountain of joy and delight. I had great German beer – Reissdorf and Jever – which came with a classy selection of hearty Wurst and tasty Brezel. No doubt this place is going to be my second home in summer when you can sit outside on Frederick Douglass Boulevard. By the number of coffee shops, bars and restaurants opening up in this area you may think “this is going to be the new SoHo” (wishful thinking of Mathieu).  Continue reading Bier



This week I gave a talk at the American Museum of Natural History – or as people here call it: The Museum. It’s an extraordinary environment for a scientist to work in. And giving a talk there in front of the researchers, students and curators was definitely a great experience. Unfortunately, the museum’s by far most famous curator, Neil deGrasse Tyson was not there, which seems to be the common case for science talks at the museum. His job is giving astronomy a voice (at which he’s just amazing, also literally as he’s the narrator for the Hayden Planetarium’s new show “The Dark Universe” which I can highly recommend!), but not contributing actively any more. Among the witnesses of my talk was also Galileo Galilei, staring at me from an original painting some 350 years old. I say it again: it was quite an experience!