On July 15-18, 2007, Matthew Templeton attended The Biggest, Baddest, Coolest Stars Conference held at East Tennessee State University. Here is what he had to say about the meeting.

The Cool Stars meeting was held at East Tennessee State University, in far northeast Tennessee. It's in Johnson City, part of the Tri-Cities area, and those of you who follow stock car racing may recognize Bristol, Tennessee as another part of the Tri Cities area. Johnson City is in the hill country in East Tennessee, on the western edge of the Blue Ridge Mountains -- it's really beautiful. The meeting itself was held adjacent to the ETSU Campus in their Millenium Center conference venue. I really enjoyed visiting, and found both our University hosts and the people in Johnson City very hospitable and gracious. I always enjoy visiting the south, though visiting the hill country almost feels like cheating -- southern summers are a lot cooler up in the hills than down in the plains! They also tend to feed visitors well in the south, and I'm embarassed to say I'll have to make a few extra visits to the gym beyond my normal schedule to make up for it.

The view of ETSU and the mountains from my hotel room	The hotel -- built about six years ago, but made to look antique	Day one begins

I was very pleased to get to go to a small, topical meeting like this one, since I typically attend AAS meetings -- which are great fun, but are so big that it's hard to concentrate on one topic. This meeting was all about stars near and dear to the AAVSO, and as you might expect, when I asked the audience prior to my talk how many had used AAVSO data in their work, at least 3/4 of the 40 or so people who were in attendance raised their hands. Several long-time friends of the AAVSO attended, including Lee Anne Willson, John Percy, Robert Stencel, and Bob Wing, and AAVSO observations featured prominently among the talks and posters. The talks themselves featured an interesting mix of observations and theory, and it was great to put faces to some of the names I've heard, read the work of, and/or traded emails with over the years but never met in person.

The Millenium Center	Lee Anne Willson (right) and Bob Stencel (center left, facing away) talking to students.	Light curves

In keeping with the topic of the conference, most of the talks were about the very largest stars -- supergiants in particular. Most of my research has been on stars on the lower-mass end of the HR diagram, so it was fun talking about neat objects like mu Cep and VY CMa that I've looked at but haven't studied before. Much of the meeting was devoted to trying to understand the details (and some basic things, too) of the late stages of stellar evolution from the huge amount of observational data we've collected over the years. How do we calibrate stellar effective temperatures for stars like this? How and where does dust form and how are winds driven? How do stars of different metallicity evolve with time? How do AGB stars interact with the interstellar medium around them? What are we learning from new satellites like Spitzer, and new telescopes and ground-based interferometers? Where does the field of research go from here?

Download Matthew's powerpoint, "Giant Stars, Astrophysics, and Amateur Astronomy"

As an example of some of the discussions going on, Lowell Observatory astronomer Phil Massey and his former REU student Emily Levesque gave back-to-back talks on understanding the basic properties of massive, supergiant stars. Even something as simple as placing these stars accurately on an H-R diagram is a non-trivial task given the dusty environments around these stars, as well as the strange chemistry and physics that goes on in the atmospheres of cool giant stars that form dust. One interesting problem that seems to have been noticed (and now resolved) is that several of the brightest supergiants like mu Cep used to lie redward of the Hayashi Limit (where stars are fully convective) in the H-R diagram, which should be physically impossible. New calibration work of the colors of these stars reveal they're slightly warmer and dimmer than originally thought, and they now lie right where stellar models say they should.

Another example: Albert Zijlstra gave a talk on the evolutionary differences between relatively metal-rich AGB stars in the Milky Way, and metal-poor ones in the Large Magellanic Cloud. The differences in initial metal abundances lead to substantial differences in the apparent chemistries of LMC AGB stars. It turns out there's very little silicon produced in LMC AGB stars, and so there's very little silicon oxide grain formation and dust. As a result, nearly everything in the LMC is a carbon star. The lack of dust makes it harder (but not impossible, as Lee Anne Willson pointed out) for LMC AGB stars to lose mass. Does that mean you're more likely to get core collapse supernovae out of low-metallicity populations?

Robert Stencel talks about stellar winds and the interstellar medium	Afternoon break

In addition to the neat science discussions that went on at the meeting, I was pleased to meet several local amateur astronomers that were attending the meeting. The organizers made a point of inviting variable star astronomers from local astronomical organizations, and there was a great mix of professional astronomers amateur observers. I even showed off the AAVSO website and observing resources to a couple of folks, and hopefully we'll be seeing observations from them soon! It was great connecting with long-time friends of the AAVSO, too, and look forward to seeing them at future AAVSO meetings.

Coming away from the meeting, I got the impression that there's an awful lot of work left to be done on giant stars, and also got the impression that the AAVSO and organizations like it have an important role to play. The amateur community has continued observing bright variable stars while many national and college observatories have moved on to doing deeper photometry with larger telescopes. The brightest stars are the ones easiest to do very high-resolution spectroscopy of, and are also the ones easiest to observe with ground-based interferometers. There's still a huge amount of astrophysics to be done at the bright end, and I think it's an opportunity for more collaboration between the AAVSO and the astrophysics community.

Thank you Matthew for that descriptive account of the biggest, baddest, coolest stars conference.