Chris Lintott’s Universe

My first AAS post was a nod to the talk I’ve just been to, a review of how astronomers meet their end by Thomas Hockney of the University of Northern Iowa. I was standing at the back having just come from another session, and so didn’t catch the names but here are the highlights:

First, the good news. Most astronomers die from natural causes. The most notable exception is probably Giovanni Bruno who was burnt at the stake. Dr Hockney noted, though, that maybe he shouldn’t be considered an astronomical martyr, having been killed for heresy not astronomy, and that he in fact deserved little sympathy having returned to Rome. As Hockney commented, any sane person should at least expect the italian inquisition.

The catalogue of slaughter included the Soviet astronomer killed in one of Stalin’s purges who unfortunately implicated the rest of his observatory staff as spies before he went, the asteroid hunter killed while one discovery away from his 100th minor planet, the great Persian astronomer Ulugh Beg who, killed by his son, goes down as the only astronomical patracide (to date) and many, many more…

Astronomy can sometimes feel like an arms race between observers and theorists. Both groups are often convinced that they’re completely right and – at least over a drink at the end of the day – take great pride in being ahead of the game. The latest battleground is in the field of extrasolar planets, and results from this lunchtime’s press conference will have cheered both sides.

Rory Barnes of the University of Arizona scored an early goal for the theorists, proudly announcing the first successful prediction of a planet since Neptune was discovered more than 160 years ago. His theory suggests that systems with multiple planets are often dynamically unstable, meaning that a small change in their orbits would lead to chaos. He also suggested that all such positions tend to have planets – solar systems tend to be ‘packed’. The system he studied, HD 74156, was already known to have two planets, and computer simulations indicated the presence of a gap. Sure enough, a couple of months ago, a planet was found in the gap just as Barnes predicted. Sara Seager, who gave an excellent talk on the field yesterday, congratulated him, and pointed out that this field littered with predictions which turn out to be wrong – but not this one.

Any theorists who were looking forward to the full time whistle should have listened to Carl Melis’ talk just a few minutes later. Looking through an old data set (from the IRAS satellite which went into orbit in 1983). His team have found two very confusing stars. They look like a type of young star called classical T Tauri stars, which have dusty disks, jets and lots of infrared light (see image above). So do the two stars Melis was studying, but there isn’t much lithium in them, which indicates that they are old. (Stars `burn’ lithium so its concentration should be highest when they’re young). So these are old stars pretending to be young, and possibly undergoing a second wave of planet formation. No-one predicted this, and I’m looking forward to seeing what the reaction might be and what explanations people will come up with.

I like the United Kingdom InfraRed Telescope (UKIRT); they do amazing work and have been doing so for 25 years. However, they’ve just released one of the most stunning data sets I’ve seen for a long time – the first release from their deep infrared survey, UKIDSS. This is the deepest and largest infrared survey ever made, the result of work that’s been going on since 2005. Sadly I missed the press conference as I was working on my talk, but luckily, Pamela has the full story here. And if you’re more a pictures than a words person, I recommend you jump straight into the site here and explore the gallery. The images are great, but my favourite UKIRT image is still the one below – the Chicken nebula.

Update Stuart reminds me that there’s an amazing Zoomable image from the part of the survey that looks along the plane of the Milky Way.

I spent the morning in the science session devoted to galaxy morphologies – shapes- and environments and the lunch break with my press hat on listening to the latest results from Hubble (the telescope, not the astronomer; even a repair mission won’t help him now). There was lots of good stuff at both, but three items in particular grabbed my attention.

The first was the talk by Preethi Nair from the University of Toronto who has classified 15,000 of the brightest Sloan galaxies by eye. Her classification is much more detailed than ours, and includes many of the things we’ll try to do with Zoo 2 when it launches (hopefully in a month or so). The important thing from our point of view is that she agrees that visual classification makes a huge difference to the results; she found 20% difference between her ellipticals and those classified by looking at the concentrations of the galaxies. (Ellipticals – on average – are more concentrated – there’s more stuff in the middle – than spirals).

The second came in the press conference talk by Duilia de Mello. Her group have been studying a ‘blue blob’ near the classic spiral galaxy M81, which turned out to be a group of stars forming outside the main disks, probably as a result of interaction between M81 and its neighbours, the most prominent of which is M82. Indeed, Hubble images show some older stars which date to the time of the last major interaction between the systems.

The story of the blue blob should be ringing bells for all of you who read the Galaxy Zoo forum. We’ve been puzzling about a blue blob known as Hanny’s Voorwerp for a while, and on face value it does look like the blue blobs discussed by de Mello’s team. We’re working on getting a quick spectrum of the Voorwerp; the other possibility is that it’s a distant galaxy from which we’re only seeing one spectral line. Either way, it’d be great to find out which.

Finally, a cautionary tale from Gene Byrd. He was talking about NGC4622, a seemingly ordinary spiral galaxy. The only problem is that its two outer arms are rotating in the opposite direction to the two inner arms Byrd’s team managed to identify via some very clever image processing. Some of our GZ results assume that our results assume that the direction the spiral arms are pointing tells us about the direction of rotation of a galaxy. Most (more than 90% of galaxies do), but this sort of thing is a reminder that we don’t really understand spiral arms at all.

Update : You really should keep an eye on the hard work being done over at the Astronomy Cast conference page. With multiple people covering (almost) all the things going on at the meeting, this is the future of reporting from big conferences like this. And I’m not just saying that because they’re hosting drinks later this evening.

I’ve said again and again that the most exciting area of observational astronomy at the moment is the search for extrasolar planets. It’s incredible to think that in not much more than a decade we’ve moved from finding the first planet in a solar system other than our own to having several hundred in the catalogues. It’s fitting that the first science talk of the meeting, by James Kasting of Penn State, dealt with exactly that. While he talked about lots of the exciting results, it also proved an excellent reminder of just how hard it is to get science done sometimes. With the honourable exception of Kepler, due for launch next year (which he mentioned) and the French COROT mission which I don’t think he did, most of the planned planet seeking missions are either under review or postponed, both in Europe and the US.

Meanwhile, the brave planet hunters soldier on, looking for the first rocky planets in the habitable zone of their star (or, as I prefer, the Goldilocks zone – not too hot, not too cold). Some thought we’d got there with the discovery of Gliese 581c last year, but new results Kasting talked about show that’s it’s too warm, receiving 30% more light from its parent star than Venus does. Time to keep looking…

Update : More detailed lecture blogging here.

Astronomers do not easily get up for an 8am start. I’m sitting in the main meeting room and they’re can’t be more than 100 of the few thousand attendees here…

Just arrived in Austin, Texas for the American Astronomical Society meeting, easily the largest conference I’ve been to since I started my ‘career’. The abstract book and program are each the size of a novel, and working out what to see is going to be interesting. I’ll be posting updates here, but you should also keep an eye on Universe Today,Bad Astronomy and Pamela Gay for all the latest news.

I was going to write an overview of the week, but I opened the abstract book and turned straight to the following; more when I’ve stopped seeing things.

How Astronomers Die
Thomas A. Hockey – University Of Northern Iowa.
Presentation Number: 082.05
Most astronomers throughout history died of natural causes. Atypical deaths, gleaned prosopographically from the author’s Biographical Encyclopedia of Astronomers (Springer, 2007), are discussed.

Today marks the third anniversary (in Earth years) of Spirit‘s landing on the Martian surface. It bears repeating again and again that this is a mission whose design lifetime was 90 days, and yet both Spirit and Opportunity are still going strong, despite dust storms and all that Mars has thrown at them. It’s hard to remember now, but the buzz around the landing was initially negative. The European probe Beagle 2 had just failed to safely land, and so it was with great relief that we all heard of Spirit’s success. The rover suffered software problems almost immediately, and journalists began to scent another NASA failure story. When I was at JPL a while back the press officer escorting us described photographers queuing up to get a picture of the full scale replica of Spirit in the courtyard as it was battered by wind and rain, symbolising the difficulties the real thing was having on Mars. Since then, Spirit has been nothing but a success.

This image is one of my favourites; assembled from Spirit images by the contributors on Doug Ellison’s Unmanned Spaceflight forum, it shows the rover on top of Husband Hill.

To catch up on its amazing story, can I recommend two of the Sky at Night interviews I’m proudest of, both with the rovers’ lead scientist, Steve Squyers? The first is part of our planetary round up from October 2006 and the second is in our Mars special from last February (3 minutes in).

Less seriously, can I recommend this article from the Onion?