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Showing posts from November, 2012

‘Overmassive’ black hole holds the mass of 17 billion suns

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A very quick post tonight. I was interviewed to comment on the discovery of a very massive black hole, much more massive than we would expect from the galaxy in which it is found.

This is a big black hole. Say it slowly... 17 billion times more massive than the Sun. That is a lot of mass in a very small volume.

The article is presented in The Conversation. You can read it here, and, as ever, I am happy to address any questions in the comments spot below.

Black holes. You have to love them!

Dynamics in the satellite system of Triangulum: Is AndXXII a dwarf satellite of M33?

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I am playing serious catch up here, as we've had a wee flurry of papers accepted in the last few weeks, and I want to make sure they all get a mention. The good news is that I should have plenty to post over the Twilight Zone of the Christmas/New Year Period.

Today's paper takes us back to M33, and a bit of a curly question. As we've seen over recent papers, we've seen that the larger Andromeda Galaxy has a large population of dwarf galaxy companions, at least about 30 of them buzzing around (although not randomly, something I will come back to in the New Year).

M33 is about a tenth the size of Andromeda, and so we have the question "Does M33 have any dwarf galaxies of its very own?" This is actually a little complicated because M33 is in orbit about Andromeda, and passed near the larger galaxy a few billion years ago. It will do so again in a few more billion years.

Here's a map of the dwarf galaxies that we have found in the PAndAS survey, taken from th…

Kinematics of the stellar halo and the mass distribution of the Milky Way using BHB stars

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I've been back for about a week, but it has been busy with a number of things.

Firstly, success in the current round Australian Research Council Discovery Projects. I'll write about this in a little more detail soon, but here's the summary.
There has been some uncertainty in the current round of funding, but it has all come out in the wash.

But there is more news. When I was traveling, PhD student, Parjwal Kafle, had his paper on measuring the mass distribution in the Milky Way.

This might strike you as a little odd. We live in the Milky Way, and it is the most studied galaxy in the entire Universe. Surely we know the mass of our own home galaxy? Don't we just add up all the stars we can see?

Well, if the stars were all there is, that would be correct. But we know there is more, much much more! There is dark matter, this stuff that dominates the gravitational attraction of the Universe. Our Sun is kept in its orbit by the halo of dark matter that surrounds the Galaxy.

On the good ship Volendam

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I'm back! But where have I been? I've spent on 10 days on a cruise ship, the m/s Volendam. Here's what she looks like.
I wasn't just enjoying myself, I was there to lecture astronomy. The trip trundled from Darwin to Perth, calling in at the islands of Komodo and Lombok in Indonesia.

To pay my way, I had to give five lectures. I wasn't sure who the audience was (it turned out to be mainly people over 60, but from a range of nations), so I talked on
The Secret Lives of GalaxiesThe Big and Small of StarsHow to fall into a Black HoleJust what happened at the Start of the UniverseDark Energy and the Long Term Future of the Universe As well as me, there was also Victor Gostin of the University of Adelaide, who spoke on the geology and geophysics of South East Asia and Australia - did you know there was a now drowned continent called Sundaland (not to be confused with Sunderland!)? I didn't, and I think it was cool. Here's a map from wikipedia.
Anyway, I think tha…