Sunday, April 13, 2008

MARAC 2008 Review

Well, the MARAC meeting is over. There's some highlights, some low lights, and since several talks were done with no lights (aside from the projector) there was some nap time too.

Unfortunately, I had to miss the first two sessions due to my Nanotechnology class, which is a shame, because some of the talks seemed pretty interesting. Josh Tartar from Mizzou, laid out the background for the larger framework which he, his adviser (Angela Speck) and another grad student (Adrian Corman) have been working on involving some really interesting stars. These stars do the typical thing that most post main sequence stars do as they die; They puff up and slowly shed their outer layers in soft puffs of material.

But the thing that's really cool about these stars is that they're at the very end of this asymptotic giant branch phase and doing some serious dredgins up of the carbon interior and losing the very last layers at a frenzied pace. The effect of this is that over a relatively short amount of time (tens of thousands of years short), the entire star becomes enveloped in shell of it's own making so optically thick (due to dust grains and heavy molecules forming out of the fresh material) that the star itself is no longer visible! The work that these guys are doing (which I got to catch up on through the later talks and chatting with Josh at dinner). Essentially, they're taking the spectra from these shells, and using a program to try to recreate the observed spectra.

This is a lot harder than it sounds because there's a lot of variables: composition, size, temperature, optical depth... Some of those can be observed somewhat and fixed, but there's too many to completely say so it takes a lot of playing around with. And to make things worse, the solutions can become degenerate. In other words, two sets of parameters may return the same spectra. Sometimes they can be ruled out as possible (such as one which returns the temperature as higher than is realistically possible), but other times, it's harder to do. Regardless, it's an interesting project and Angela had purple and black hair with a hot accent so all the more fun there.

Another talk I missed came from James Roe of the Astronomical Society of Eastern Missouri letting everyone know that they have their new observatory up and running that has the equipment to do some basic photometry and they're willing to do some of the routine monitoring for others whenever possible.

The first talk I saw from someone at KU was one from John Ralston. The only time I've really had to deal with him here was when he subbed in my Quantum class one day while the normal professor was at a conference. Essentially he told us to ignore everything we'd learned because none of it was pretty in theory and h-har equals 1. Ralston is a theorist.

Anyway, he has a tendency to make his slides using the Mac equivalent of Paint, so they're brightly colored to the point of being garish, and impossible to read. Since I'm not a theory person I tuned out for most of the talk, but the main message was that Dark Energy doesn't appear to be uniformly distributed.

The next talk was by another KU professor: Danny Marfatia. I didn't intentionally tune out on this talk, but he has a tendency to start off his sentences in a nice strong voice and trail off into mumbling, so I didn't really follow much of what he was going for. Only that the fine structure constant, α, may be varying over the history of the universe, but if so, then only very weakly and not in any terribly important way (sorry to get your hopes up Creationists).

The first talk of Saturday was from Steve Black from Washburn University and was probably one of the worst talks I've ever seen given. The entire talk was about being able to observe stars as they were occulted by the moon. Typically, if you want to do good photometry, you need to do this when the moon is still pretty new so the glow from the moon doesn't wash out the star. But by observing in the IR, you can do observations until first quarter.

That's all and good, but what does that tell us? Protip: If you want to have people care about your talk, tell them what's important about it.

The next talk was on dynamic bar mode instabilities in neutron stars by Karen Camarda from Washburn as well. I'd heard this talk a week or two back so I took a nap for this one, but the idea is that, as neutron stars rotate, the instabilities can cause the star to collapse, not to a point, but into a bar. At least temporarily. Not terribly exciting in and of itself, but these quick collapses would make strong distortions in space time and should be able to generate the highly sought after gravitational waves. Since neutron stars are more common and closer than many other things that could do this, this may be our best bet at detecting gravitational waves.

The single best talk came from Todd Boroson, the interim director of the National Optical Astronomy Observatory. Recently, the NSF (which funds NOAO) did a review of the program trying to look at how effective they were being. The result was that the NOAO was "moving too fast". Too much investment was being made on large telescopes and not enough on smaller, workhorse ones. Unfortunately, there's a bit of a catch 22 with that. The NOAO hasn't been spending money on these telescopes because astronomers haven't been applying for time on them (the 2.1m was underbooked recently). Astronomers haven't been applying for time on them because the equipment isn't up to par because the NOAO hasn't been spending money on them.

So they've launched a new program called Renewing Small Telesopes for Astronomical Research (ReSTAR). Of course, they also intend to keep working on getting more time on major observatories like Keck and Gemini as well as investing in new projects. Additionally, they're looking at starting classes which would teach observational techniques at these nationally funded observatories to allow students to get experience they couldn't get at smaller universities that don't have strong research programs.

Brenda Culbertson gave a talk on the use of the planetarium at her school. It wasn't all that novel or exciting. It essentially amounted to "Planetariums are cool and kids say it helps them understand things better." Duh.

Christoper Sidell and Kevin Lee from University of Nebraska gave two talks on some new classroom software they've been working on. The first was a new lab on variable star photometry. I really liked this and wish I could use it in my lab. Unfortunately, it's a bit over the heads of my students since it doesn't really cut many corners. It simplifies a few things, but it really shows all the steps you have to go through in real astronomical data processing: From correcting images for noise, to aligning them, to getting the data.... An excellent lab that I probably will try to water down a bit and use for my classes sometime in the future.

Their other program is called Class Action and is an in class teaching program that covers major topics in astronomy. It's designed to allow for real time feedback in the classroom. It features quizzes that can be approached from several different angles so it's not quite so routine, and in case the students get stuck, it also has tools with some really fun animations and tools to help explain the topic.

Paul Temple from one of the local astronomy groups gave a quick talk on the possibility of using RGB cameras (essentially expensive webcams) for actual astronomical research. The filter systems aren't all that close, so standardization would be shot, but it's not too far off in the green (V/G) filter. At the very least, they can allow for eclipse timing. Paul was going to report on how close he could get on standard stars, but due to a hard drive crash, was unable to put that together in time.

The next invited talk was from Eric Linton of Benedictine College talking about using Cerenkov radiation for use in observing extremely high energy gamma rays. Since gamma rays can't make it through our atmospheres and space based telescopes are expensive, astronomers need another way to observe this spectral regime. As gamma rays enter out atmosphere, they suddenly find themselves traveling faster than the speed of light in the local medium and make a shower of all sorts of crazy particles. By detecting these particles, you can start to reconstruct the image presented by the actual gamma rays.

According to Brian Thomas from Washburn, the famous supernova to be, Eta Carine, isn't a threat to us. Even if it were as bright as the superluminous 2006gy, it's still too far away to be felt much. Even increasing it by 1000 times that, it still would barely dent our atmosphere. The novel bit of this research was asking what the effect would be on our endocrine system. The endocrine system is partly our internal clock, so if Eta Carine blew and suddenly it was bright all night too, that might screw with things a bit. And since the endocrine system also controls the immune system, that's a bit worrysome. But the predictions say that at that distance with the expected size of supernova Eta Car will produce (which will be damn big) it still won't be much more than -7 apparent magnitude. Bright enough to see during the day, but still far fainter than the full moon. So nothing to worry about.

Baker University's Ran Sivron talked about modeling the accretion disks of black holes and how energy propagates through it as a means to determine (or at least place constraints on) the mass of the central object. It looks like some of these black holes may be 3x less massive than previously thought. But what was really cool about this project is that it was, in large part, done by high school seniors! Way to show 'em how cool astronomy is!

Jeff Wilkerson from Luther College talked about looking for short-period variable in open clusters. Jeff had talked about the same topic at MARAC last year. His program is really just a gigantic crap ton of data collecting. On any night when it's clear, he and his students head to the meager observatory his school has, and just shoot image after image of the clusters he's observing. In the past decade, he's collected nearly half a million images. The trick is sorting through all this mess, trying to find the interesting stars out of the hundreds or thousands in each cluster. That was the focus of this talk, in which he described how to try to find these stars using how much they had to be normalized to get each frame to have the same standard system.

The last talk was given by Scott Baird from Benedictine in which he described the effect of reddening on metalicity estimates in the Small Magellenic Cloud. The short version was that, even using some fairly significant different reddening amounts, the metalicity didn't change enough to be outside the error in it that comes from the inherent error in photometry. In other words, it's not that important at this level.

So that's the MARAC conference. Now excuse me while I get back to writing the three different talks I have to give in a week.


Wayne said...

Thanks for the lab material links, I'll have to check those out. As for Eric Linton's talk, I'm betting you meant to say "cosmic rays" rather than "gamma rays", right?

Jon Voisey said...

Nope. It really was gamma rays.

Wayne said...

In that case, I don't understand your comment about the rays moving "faster than light" in the atmosphere. That sounds like an effect similar to what causes Cherenkov radiation, but that's a particle phenomenon. I can see how a gamma ray could hit an air molecule hard enough to cause a particle shower, but that "faster than light" bit is what made me think you meant cosmic rays.