Star formation near and far

 

Artist’s impression of the face-on structure of the Milky Way galaxy with the names of the spiral arms indicated.

This week our astronomy colleagues at the University of Heidelberg are hosting a conference on Galactic Scale Star Formation here in Heidelberg, and what a treat it is to be able to attend this week-long event so close to home. So far there’s been lots of good talks showing data from recent large-scale surveys of the Galactic plane, such as ATLASGAL and the Bolocam Galactic Plane Survey in the (sub-)millimetre and HiGAL in the far-infrared, and also some great talks on star formation in other galaxies. The Galactic plane surveys form the perfect complement to the Spitzer surveys GLIMPSE and MIPSGAL, so at Milky Way Project we’re big fans already.

I presented some of my recent work with our Milky Way Project bubbles in yesterday morning’s session. I gave a whirlwind tour of our recent statistical analysis paper (just this week published in the Astrophysical Journal), and showed a few things I’ve been working on recently to address some uncertainties in the analysis: the distances to the bubbles in our sample, and the evolutionary degeneracy we came up against with the RMS survey data used for the correlation analysis.

The main idea is to tighten up the results we presented in the paper and perhaps show some stronger evidence for star formation being sparked in the vicinity of expanding bubbles all over the Galaxy. But from the many questions and comments I received yesterday after the talk it’s clear that such correlations of large scale surveys at different wavelengths, and the ability to place objects in 3D space in the Galaxy, are really useful for improving our understanding of Galactic star formation in general.

It’s very pleasing that Milky Way Project is getting such an enthusiastic reception in the community! I’m itching to get on with more follow-up work now.

Longitude-velocity plot of the CO gas in the Milky Way Galactic plane, with bubble locations overplotted. Click to enlarge.

After spending a couple of days cross-matching our MWP bubbles with catalogues of HII regions (from Anderson & Bania 2009 in black and Anderson et al 2012 in red) and stellar clusters (from Morales et al, in preparation, in orange), whose velocities have all been measured, I plotted the corresponding velocities onto the composite longitude-velocity (LV) map of the CO gas in the Galaxy, produced by Dame et al in 2001.

Incidentally, measuring the distances to objects in our own Galaxy is a real pain, so I’m delighted that others have already put in so much hard work on that subject. Just yesterday Yancy Shirley of the University of Arizona gave a talk about his work on measuring distances to BGPS clumps, for which he has to visually inspect ~25,000 (if I remember the ridiculously large number correctly) radio spectra.

In any case, this LV map shows the different velocity components of the molecular gas in our Galaxy against galactic longitude. If you imagine looking through the plane of the Galaxy, gas at different distance will be seen to travel at different velocities either towards or away from the Sun, and that’s what is visualised in a longitude-velocity plot.

It’s particularly useful for tracing large scale structure in the gas distribution, particularly the spiral arms where most of this gas is concentrated. In this case, we can see that  the bubbles generally trace the molecular gas very nicely, and our users have even identified some bubbles beyond 15 kpc, in the Outer Arm of the Galaxy. With apologies to Rob’s student, there’s a new “Most Distant Bubble” in town! This plot is very preliminary though and needs much more work to be properly robust.

There are interesting things to learn from this plot, and of course we have around 10 times more bubbles to add than are shown in this plot. I’m learning as I go along as well, hopefully more exciting results to write about and publish in the near future.

Some references

L. D. Anderson, & T. M. Bania (2008). Resolution of the Distance Ambiguity for Galactic HII Regions Astrophys.J.690:706-719,2009 arXiv: 0810.5570v1

L. D. Anderson, T. M. Bania, Dana S. Balser, & Robert T. Rood (2012). The Green Bank Telescope HII Region Discovery Survey: III. Kinematic
Distances ApJ, 754 (1) arXiv: 1205.4228v1

T. M. Dame, Dap Hartmann, & P. Thaddeus (2001). The Milky Way in Molecular Clouds: A New Complete CO Survey Astrophys.J. 547  792-813 arXiv: astro-ph/0009217v3

Sarah Kendrew, Robert J. Simpson, Eli Bressert, Matthew S. Povich, Reid Sherman, Chris Lintott, Thomas P. Robitaille, Kevin Schawinski, & Grace Wolf-Chase (2012). The Milky Way Project: A statistical study of massive star formation associated with infrared bubbles ApJ , 755 (1) arXiv: 1203.5486v2

SPIE 2012: Instrumentation Schmooze-Fest

Another week, another country. This week I’m at the SPIE conference on Astronomical Telescopes and Instrumentation. This is the large conference organised every 2 years by international optical engineering society SPIE, alternating between venues in North America and Europe. The 2012 edition is in Amsterdam – and a joy it is to be here.

Having lived down the road in Leiden for over 3 years I enjoy coming back to the Netherlands. And bewildering as these large conferences are, it’s nice to have one in a country where I speak the language and vaguely know my way round. That said, I did get hoplessly lost biking to the RAI convention centre on the first day. It’s also great to catch up with my former Dutch colleagues, many of whom are also here.

There’s always lots and lots of talks at SPIE, but the real fun is of course in the fringe events – especially those that include a few drinks. As you know, I love a bit of gossip, and there’s nothing like a few beers to get some good inside snippets from the many projects represented here.

This time round I actually have my name and picture in the programme, as I’m the invited speaker in the Women in Optics special session. This is an evening network event with drinks and an hour-long talk, and the honour of giving that has come to me. I was pretty chuffed to be invited, although having only rarely spoken about my interest in science & society issues outside of pubs, I’m a little daunted. Once I’ve recovered, I might write a bit more about the talk on here, or share my slides – I’ve tried to squeeze in some of my favourite things in life: dotAstronomy, kittens, histograms, telescopes,  MIRI, high fashion, celebrities and beer. And I’m lying about only one of those.

The session starts at 16:30 with drinks, then the talk at 17:00. If you’re coming along, I look forward to seeing you there.

Champagne and Chocolate

Many of my recent blog posts have all been about Milky Way Project, and there’s a good reason for that. The publication of our first paper, which is in press at the moment with Monthly Notices, was just a first big milestone, with more to come. I’m currently writing a follow-up paper using the initial data catalogues, and as I’m scheduled to give a talk about it at the end of the month at the joint UK/German National Astronomy Meeting in Manchester, I’d better make a move on with getting the results out.

The paper won’t be the photogenic blockbuster that Rob wrote for us,  but just in case you don’t share my histogram-fetish (… you simple soul!), I’ve managed to find space for one rather sexy bubble picture to add a bit of spice. If and when the paper gets accepted I’ll instruct the editor to place it on Page 3.

My own data adventures aside, this week was another heap of fun for the project. NASA put out a press release to mark the first data release. It didn’t get picked up in too many places – there was Astronomy Magazine, Space.com, and also a short piece in the Mail Online with obligatory pretty pics of the Spitzer images and our MWP heat maps. The Mail upped Eli Bressert’s “champagne bubble” quote to liken the Milky Way to a nougat-y chocolate bar.

If I’m being a pedantic scientist, I should add that neither of those analogies are actually very accurate. Champagne bubbles are maybe somewhat similar in that they’re lighter than the liquid they’re in, but our interstellar bubbles aren’t thought to be floating or rising through the interstellar medium. But they do expand. As for chocolate bars… No, that doesn’t work either.

At Milky Way Project HQ, we launched a new phase of the project. While we continue to collect your ‘regular’ bubble drawings, we’ve now added close-up images of bubbles that are already in the catalogue, for which we’re trying to get more precise sizes and thicknesses. Rob explains all here. Our drawing tools were fairly coarse, as some users had remarked, particularly for drawing smaller bubbles. So with these new images we will try to gather more precise measurements.

I’m really looking forward to the NAM conference later this month. I haven’t been to one of these meetings since the first year of my PhD (Dublin!), and they’re great for catching up with old friends and colleagues. Having it joint with its German equivalent meeting (the AG) means that both old and new friends will be at the meeting. Another factlet is that I’m actually half-Mancie, and although my association with the city is pretty patchy (what, you haven’t noticed my striking Northern accent?), it’s fun to be there.

Instrumentation School

Not much blogging activity in the last week as I’m travelling around Europe for a bunch of meetings – expect updates on dotAstronomy and Milky Way Project in the next week, once I’m back at home.

In the mean time, I wanted to share the announcement of this interesting instrumentation school taking place in Toronto this summer. Since a few years, the University of Toronto hosts the Dunlap Institute, which is specialised in astronomical instrumentation. It’s really great to see such centres of excellence being set up – after all, very little science without good instruments. This course looks excellent for students who would like to get involved in instrumentation.

American Astronomical Society Meeting, Austin

AAS

This week I’m at the meeting of the American Astronomical Society in Austin, TX. I’m excited to be here for a number of reasons, first and foremost that I’ve never been to a AAS meeting before. It’s one of the biggest gatherings of astronomers, so there’s lots of people to meet, including some old friends and colleagues I haven’t seen in a while. And of course there’s the talks, the posters, and the wonderful city of Austin:

Motel

I’m planning to organise a meet-up for DotAstronomy alumnae/i and enthusiasts this evening, so keep an eye on twitter for details of that.

As always there’s a big media presence at AAS so expect some astronomy stories in the papers and online this week. AAS have a list of blogs and twitter accounts covering the meeting (mine’s not on there but if I hear interesting talks I’ll certainly write something about it). I’ve had lots of discussions recently about science reporting, peer review, blogging and such, so I was interested to read Blogging & Tweeting guidelines in the printed programme. A few selections:

[…] Please do not publicly report private conversations – only scheduled presentations and public comments are fair game for blogging, tweeting, etc.

Remember that many presentations at AAS meetings concern work that has not yet been peer reviewed. So think twice before posting a blog entry or tweet that is critical of such work. It is helpful to receive constructive criticism during the Q&A after your talk or while standing next to your poster, but it is hurtful to be raked over the coals online before your session is even over and with no easy way to respond. […]

That’s quite sensible really – it’s not trying to stop people from writing or commenting, just to be balanced, fair and take the status of the work into account. There’s also an embargo policy for the meeting:

When meeting abstracts are available publicly, either electronically or in print, they are not embargoed.Abstracts reflect the situation at the time of submission and often do not correspond exactly to the paper that is ultimately presented, usually months later. Reporters should note that preparing a story based exclusively on an abstract is ill-advised.Some results to be presented at AAS or Division meetings are also the subject of papers whose manuscripts are available via preprint servers such as arXiv.org or that have already been published in scholarly journals. Such publicly available results are not embargoed.Interviews with presenters, as well as graphics, animations, and other information to be presented for the first time at the meeting, are embargoed until the time of presentation, where “time of presentation” means the start time of the oral or poster session in which the paper will be given, or the start time of the corresponding press conference (if any), whichever comes first.For more information, see http://aas.org/press/embargo_policy.

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