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!

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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

Chaos in the Galaxy

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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

ESO Messenger

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An article I just wrote with Steffen Mieske (ESO) about our Satellites and Streams in Santiago meeting earlier this year appeared today in the ESO Messenger. Go, check it out!

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.

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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

GONYC

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On the last Monday of April we had our first meeting of star cluster aficionados in New York: GONYC – Globular, Open, Nuclear and Young massive star Clusters. Together with Nathan Leigh from the American Museum of Natural History I initiated this monthly get-together, because we both felt a bit detached from the rest of the star cluster community. This is mostly due to the fact that star cluster research is significantly underrepresented in the U.S., so we have to connect more actively across institutions. We decided to meet at the AMNH since it is the birthplace of one of the most important conference series in the star cluster community – the MODEST meetings. The long-term goal is to host a MODEST meeting at the AMNH again after the first one in 2002. It’s a great time for GONYC – the rapidly growing fields of nuclear star clusters, young massive star clusters, and super-massive star clusters like UCDs has boosted interest in basic gravitational dynamics and star cluster physics. If you want to join the meetings (next one is on May 20) contact me or Nathan!

How to weigh the Milky Way

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The Northern Hemisphere of the sky as seen by the Sloan Digital Sky Survey. Stellar streams stick out from the vast number of stars in this view, of which most lie within the Milky Way disk. The Palomar 5 stream is the densest of the stellar streams discovered so far and turned out to be a perfect scale and yardstick for our understanding of the Milky Way. (Credit: Ana Bonaca, Marla Geha and Nitya Kallivayalil with data from the Sloan Digital Sky Survey.)

The Milky Way consists of roughly 100 billion stars like our Sun, which form a huge stellar disk with a diameter of 100-200 thousand light years. The Sun is also part of this structure, hence, when we look into the sky, we look right into this gigantic disk of stars. The vast number of stars and the huge extent on the sky make it hard to measure fundamental quantities for the Milky Way – such as its weight.  Continue reading How to weigh the Milky Way

Satellites and Streams in Santiago 2015

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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