Saturday, July 01, 2006

Astronomy Internship - Day 21

This morning I worked on trying to reduce some more images. Unfortunately, when I opend the next one I was to work on, the image looked as if it had been underexposed. Only the brightest stars showed up in any manner. This meant that the programs would not work on the image because there was nothing to really work on.

So I skipped that and went on to the next image. I got about half way through processing this one before I decided to quit on that for the day. I didn't really feel like going through the image and locating the 202 stars it wanted to use as model stars.

At 3:00 it was time for our presentations. First up was Brendan, who gave a brief introduction to eclipsing binary stars.

Eclipsing binaries, as the name might imply, is a pair of stars in orbit around one another with their orbital plane inclined in such a manner that, from Earth, we see one star pass in front of the other. This causes the star in front to block light from the other for a regular amount of time on a regular interval which results in a dimming of the system that can be observed. Such systems are useful because they allow us to directly determine various properties of the star that we would be unable to determine for isolated stars, such as relative masses and sizes.

Next up was Peter, who discussed cataclysmic variable (CV) stars.

These stars are similar to the binary stars Brendan had been discussing, with the exception that they orbit very close together and the tidal forces cause mass to transfer from one to another. If the star that the matter is falling onto is a white dwarf (the dead core of stars with mass similar to our sun), the matter falling onto it can pile up until there's enough pressure to briefly reignite hydrogen fusion on the surface, causing a nova (not supernova).

Mike was next up and also discussed CV systems.

After Mike was Tiara who discussed the bigger type of explosions: Supernovae.

Hers focused on Type II supernovae which are massive stars that explode as they die. More specifically, her project is on Type IIp, which get extremely bright, fade, and then level off (plateau) for a time. Such supernovae are only expected to occur in red supergiant stars but the most famous (SN 1987a) occured in a blue supergiant, and the one she'll be studying was in a yellow supergiant. Obviously, the models for such events need some work. But that can't happen until more observations are made and we have a clearer picture of what's going on.

My roomate, Peng, was next (couldn't get a picture that wasn't blurry of this jittery bugger). His presentation was on the search for extrasolar planets by transit. As with the eclipsing binaries, planets can also potentially eclipse the face of distant stars. Although we can't directly resolve the disc of many stars (only 2-3 in fact), it would dim the light of the star a miniscule amount. This amount would be about 1% for Jupiter like planets and 0.08% for ones like Earth. Currently, the Jupiter sized ones are the only ones that we could discern from background noise. Thus he and his advisor are working on data from a testbed camera that observes several hundred thousand stars in an area 14 full moon widths in height and width. Undoubtedly, this project will also turn up many new variable stars.

I was up next. It went pretty well. I ended up having to talk very quickly because I tried to fit a lot of information for a 5 minute presentation. I originally wanted to include 3 more slides that I was forced to cut due to time. I would have pictures, but the person I asked to take them for me apparently didn't.

Ryan was the next speaker and gave an introduction to globular clusters. He was woefully unprepared and had several facts wrong. Globular clusters are similar to open clusters except that they contain many more stars, generally between several hundred thousand and a million. Unlike open clusters, they have no preferred orbit around the galactic nucleus and are the oldest formations in the galaxy. Rob continued Ryan's presentation and spoke more on globular clusters.

The last speaker of the day was Kris who was speaking on dwarf galaxies.

Dwarf galaxies are loose accumulations of stars between galaxies. They're similar to clusters in many respects. There are some dwarf galaxies that appear very blue because they have massive, young blue stars, which indicates ongoing star formation. Others have no gas, and thus cannot form new stars. These ones are redder because the blue stars have all died off. Kris' studies this summer will be to work on determining if one evolves into another, or they are completely disconnected.

Afterwards, several of us headed to downtown San Deigo. We wanted to hit a club or bar, but one person forgot their ID. We found a Ghirardelli's that looked good, but the line was out the door.

Thus, we ended up at TGI Fridays. On the way back, I spotted the San Diego Convention Center which has some really cool looking stairs lit up at night:

I'll be headed there next month for Comic Con more than likely.

Finally got back to the dorms around 1:00 am.

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