Thursday, September 29, 2005

Traveling CD

The lovely Mrs. H and I are going to be in Florida this weekend for the holiday. (Yeah, I know, we're missing the actual holiday by a couple days, but then again, I'm not really Jewish either.) Here's the CD I made to while away the boredom that is driving around the flatness of southwest Florida. It might be kind of odd, seeing as how it switches from folk-pop to ska-punk at times. But mostly these are songs that have been stuck in my head lately, so I put them all in one place.

1. Gainesville Rock City ------- Less Than Jake
2. Zak and Sara ---------------- Ben Folds
3. The One I Love -------------- David Gray
4. Seven Days in Sunny June ---- Jamiroquai
5. Suite: Judy Blue Eyes ------- Crosby, Stills, and Nash
6. Babylon --------------------- David Gray
7. One Hit Wonderful ----------- Reel Big Fish
8. Three Marlenas -------------- The Wallflowers
9. Fired ----------------------- Ben Folds
10. American Idot -------------- Green Day
11. The Impression That I Get -- Mighty Mighty Bosstones
12. Clocks --------------------- Coldplay
13. Jesus Was an Only Son ------ Bruce Springsteen
14. Steve McQueen -------------- Sheryl Crow
15. Last Show ------------------ Reel Big Fish

Wednesday, September 28, 2005

Astronomy Paper of the "Day"

Well, maybe day isn't quite the proper term, as I don't know when exactly I'll be able to update this, but at least I'll try. I figure this might be a good way to clear the stack of papers out of my astronomy folder and to contain my notes.

I get my papers from astro-ph, which is over there on the right of the blog, under science sites. The papers there are mostly pre-prints, so hunting down the official reference might be tough at times, but I'll do the best I can. You can also go to ADS to look up the authors. Most of these will be stuff that I'm interested in, so expect alot of disk galaxies and bars.

To begin with, here's a short article by a friend, a mentor, and some guy I've never met.

"Anti-Truncation of Disks in Early-Type Barred Galaxies"
P. Erwin, J. Beckman, and M. Pohlen
ApJ Letters
(astro-ph/0505216)

Well, that's alot to start off with. Since I've never done this before, I'm going to define a couple terms. First off, a galaxy is a large collection of stars, gas, dust, and dark matter (unless your my former advisor). For this article, we're only going to worry about galaxies that are disk shaped (like the ones in the previous picture). And further, we're only going to worry about galaxies that are barred. A galactic bar is an oblong structure of stars and dust in the center of a galaxy. In the previous picture it is the creamy, brown structure that runs basically horizontal through the middle of the galaxy. Oh, and an early type galaxy tends to have tightly wrapped spiral arms.

Hope that's a good start.

So, what does it mean for a disk galaxy to be truncated. Well, basically, the galaxy has to come to an end somewhere. If you think about a whispy sort of water cloud here in the Earth's atmosphere, there's always a point at the edge of the cloud where it doesn't look solid anymore. You may still be able to notice some fuzz at the edge of the cloud, but you can see the blue sky behind it. The effect here is caused by the decreasing density of water molecules as you further out from the center of the cloud. Really, even if you go a little further out from the center, you might think that you're looking at clear blue sky, but really there are a few water molecules there still associated with the cloud. It's just that your eyes are not sensitive enough to notice the tiny amount of light that they're blocking.

Galaxies are much the same way, except they are made of stars giving off light instead of water molecules blocking light. The traditional view has been that galaxies end very abruptly, call this truncation. You can sort of see this on the pictures above. As you look outward from the center, the galaxy is going along emitting light steadily, and suddenly the galaxy stops. (In reality, the amount of emission at the outer edge is less than that at the center, but the drop off after the outer edge in a truncated galaxy is significantly greater.)

However, if you look more deeply with a telescope, you can find different behaviour. In this paper, Erwin et al. looked at a number of early type barred galaxies. What they found was that the majority of their galaxies were not truncated at all. These galaxies simply faded away. The decrease in the amount of light from the center of the galaxy to the outside remained constant. This is primarily an observational effect. The outside edge of the galaxy has become very dim, even though it hasn't truncated yet. The amount of telecope observing time needed to see further out in the disk becomes very large and impossible to obtain. With bigger telescopes and more time, you might be able to see edge effects.

Erwin et al. found that less than 12% of the galaxies showed typical truncation effects, but that about 25% of the galaxies showed something called "anti-truncation". What this means is that the outer edge of the galaxy is actually brighter than what we would expect from a truncated disk, and brighter enven than if the galaxy simply faded away as in the previous paragraph (even though the edge is still significantly more dim than the center of the galaxy). This is unexpected. What could be the cause?

Erwin et al. site a process that is beginning to become regarded as very common in galaxies, interactions. This image shows M31 (the Andromeda galaxy) as the big blue/white thing in the center. But M31 has a companion galaxy, M32, that is the reddish blob up and towards the right of center (really it has a number of other companions). Even though M31 is significantly bigger and more massive than M32, M32 excerts a strong influence on the movement of the individual stars within M31. Really, M31 is shaped the way it is because of M32's presence.

Through other visual evidence, Erwin et al. claim that several of the anti-truncated galaxies in their sample do have companion gaalxies. They conclude that it is likely that that anti-truncation in general is a result of interactions with companions. This is a likely conclusion since barred galaxies in general are more likely to have companions, so it is not suprising that we see anti-truncation behaviour in this sample. It is also not suprising that Erwin et al. find more anti-truncated galaxies than truncated ones, as we are finding more and more that galaxies are effected by their outside environments, and that many galaxies previously thought to be isolated are actually part of rich communities of smaller galaxies (even if we can't directly see the smaller galaxies all the time).

Things to take away from all this:
1. Galaxies have an edge somewhere, but the nature of that edge tells us alot about the local environment of the galaxy.

2. Many galaxies have small companions.

3. Even if the small companions are not directly visible, it is possible to observe their effects on a large galaxy, and infer their existence.

Hope you enjoyed.

Takin' the Metro

Don't I just love public transportation. My day is entirely different when I take the Metro to work as opposed to driving. Even though the metro ride is a bit longer (1 hour as opposed to 45 minutes), I feel so much more energetic when I get to work in the morning. And what a beautiful morning it was in DC too.

Hey, maybe if I keep taking the metro every morning, I'll start to love my job.

All right, that's probably pushing it.

Monday, September 26, 2005

Back to the Mainland

I have returned again, and the trip was, well, you know, more of the same. I didn't end up having internet access while I was gone, but I did write alot, so I'll import it over the next week or so.

Friday, September 09, 2005

Hitting the Road Again

Well, I'm off to Hawaii once again. I've got most of the stuff packed up from my office, including a few books about matlab. I had never really intended on learning matlab, it just sort of happened to me. Much like this whole job. I don't really want to learn another language, but it might actually help me deal with all the data from this experiement we're running. Also, seeing as how the company hasn't really bought me any other software that I do know how to use, I guess I should learn something.

I'm also bringing a bunch of astronomy and ed papers with me. I've been meaning to do alot of reading lately, that just hasn't happened. I'll be posting my notes on here, and if anyone other than makigirl reads this, you might enjoy some disk galaxies.

And when I get back, I'll actually get around to teaching some kids or something.

aloha.

Thursday, September 08, 2005

The Democatic Wing

I forgot to write about this the other day, but on Tuesday, I went to the Women's National Democratic Club to see Bill Lofy talk about his new book on Paul Wellstone. (You can buy the book here.

I had been interested in learning more about Paul Wellstone since that day I came home from work in November 2002 to the news of his plane crash. I had just been beginning to become seriously interested in the nuts and bolts of politics that year, and Wellstone's campaign was at the center of a lot of people's attention. Wellstone's reasoned, thoughtful stance against the war was inspirational to many of us lost in the woods of the disregarded left. Knowing that he had stood up for his core values, and that he was going to win re-election because of it made him a real hero. Democrats didn't lose in 2002 on election day. Democrats, along with all Americans, lost on the day that Paul Wellstone died.

Lofy gave an inside and touchingly personal account of Wellstone's life. Although much younger (Lofy was a staffer of Wellstone for most of his Senate career), Lofy seems to have gotten to know the Senator and his family very well. I was impressed with his speech and the power with which he carries Wellstone's message. (Lofy is the communications director at the Wellstone Action Center.) We certainly had a good time and left that evening proud to be Democrats and proud to carry on the tradition of Paul Wellstone.

Wednesday, September 07, 2005

My Afternoon of Posting Continues

Probably the last one for the day, but the Rude Pundit just nailed recent events with this post. I thought I'd link to it, so that I could find it more easily in the future.

I wonder what Bible Study would be like with the Rude Pundit?

Vegans Should Be Held to the Highest Standards

Makigirl sent me this article over the weekend, and I've been wanting to complain about it.

Where is it written in the Vegan/Vegitarian handbook that once you sign up for the cause, you must be 100% pure all the time? I don't remember hearing that when I took the Oath of Vegetarian Office.

I consider myself very much a vegetarian, and I've been one for a little over a year now. However, I ate meat last night. Mrs. H and I were at a favorite asian restaraunt in DC, and I decided to try some soup that had pork in it. If I were famous, though, the tabloids would probably running stories about it today, and calling me a effing hypocrite. The vast expanse of Middle America would be silently nodding their heads in line at the grocery store, and feel glad that in this land of individual liberty, all deviations are highlighted and harrassed until they are brought back to the norm.

I don't ever recall Andre 3000 ever telling me that I'm bad for eating animal derived products. I don't recall Andre 3000 ever sitting in judgement of the American people for their dietary choices. I don't recall Andre 3000 having the power to carry out those judgements even if he made them. I also don't really recall Andre 3000 being a "Famous Vegan" (although Makigirl may have told me once). I know Andre 3000 because he's a pretty decent rapper. That's why I don't quite find it "Baffling" (as the Arizona Republic puts it) that Andre 3000 likes to wear a wolf's tail. He can do whatever the hell he wants. It's not a fashion choice that I would make, but if he's comfortable with his actions, and he obtained the tail legally, then more power too him.

What I do find baffling is that the Arizona Republic would waste 1 kb of their hard drive on crap calling a vegan a hypocrite, when the biggest hypocrite of all continues to lie about outing undercover CIA agents, WMD's that have never been found, and a disaster relief effort that is a disaster in and of itself. Wouldn't that be a little more interesting and useful?

Still Working on the Pictures

Mrs. H has gotten upset at me describing my last work trip as the "worst ever", and maybe that's not too bad of advice, especially given events in New Orleans in the past few days. So, I'll just say that it wasn't my favorite time ever, but I did get something out of it. However, I'm still not looking forward to the repeat performance next week.

Mrs. H is also working on turning us into Red Cross volunteers. She is a good lady, that Mrs. H.

Thursday, September 01, 2005

World's Worst Vacation is Over

Well, it wasn't exactly intended to be a vacation. I was going to Hawaii to do work, but one would hope that at least I could have a bit of fun. Unfortuanately after 2 1/2 weeks of 12-14 hour days, not being provided an edible lunch for about a week, spending time in the ugliest part of Honolulu imaginable, dealing with anxioius, obsessive compusive engineers, having an admiral and other "important people" wreck a couple days worth of testing, crawling through the belly of a ship through water and hydrolic oil, seeing the primary computer of our data system crash repeatedly with no good explanation, and hearing the people back home constantly complain about why our gigabytes of data weren't getting back to them every day, I have to say that even on the one day I did have off, I didn't really much enjoy Hawaii.

Maybe when I go back next Saturday, I'll enjoy it even more. Or not.

I'll try to put some pictures up next week after I get them developed.

Oh, and Makigirl started teaching this week. Here's the first post of her second year. Her class is going to be pretty cool, so make sure you check up on her.