Yesterday was the Championship Game of the 2008 ACC Lacrosse tournament. It was a pretty good game. Virginia’s defense made some stupid mistakes early on, which lead to easy Duke goals. However, other than these stupid mistakes the two teams were fairly evenly matched, having similar numbers of shots on goal.
Going into the 4th quarter, UVa was down 11-4. However, we scored 5 goals, bringing us close. It was a very exciting 4th quarter with lots of fast-paced action. However, ultimately we were unable to close the gap and the game ended 11-9, Duke.
ACC Lacrosse Championship: UVa vs Duke on Flickr
The results of our fourth Optical/IR Instrumentation lab have been put online. The main portion of this lab involved measuring the characteristics of everything in a “bag o’ optics”. This collection of slightly defective optics contained a variety of lenses, lens combinations, flat pieces of glass, and diffraction gratings.
Astr512, Spring 2008: Group Beaton/Fields/Privon/Whelan Lab 4
Last night was the semi-annual Fan Mountain Public Night held by the University of Virgina’s Astronomy Department. As you can see from this picture of sunset (with the RRRT in the foreground), it was rather cloudy. Fortunately it cleared up for a little while, enabling the 40″ and 31″ telescopes to look at Saturn and M3.
I helped guide tours of the 40″, and it was quite nice. Everyone seemed very interested in the telescopes, especially the many kids who were there.
We were planning to observe some galaxies in the near-infrared using UVa’s FanCam NIR Imager after the public night. However, it clouded back over while we were putting the camera back on the telescope and were ultimately unable to make any observations. Oh well, that’s how it goes sometimes! We’ll try again next week…
The stellar astrophysics course I am taking has been progressing well.. we’ve been covering lots of material and it’s been quite interesting. The semester culminates in a project to write computer code to model the atmosphere of a star. Late last night I finally finished my code after several days of almost continuous debugging. Now, with a calculated temperature profile of the atmosphere, my program calculates the mean intensity of the radiation at a range of frequencies (covering the the near infrared through part of the UV) at a variety of the depths in the atmosphere.
In order to solve the radiative transfer equations, we used the “Eddington Factor method” in conjunction with the “Feautrier method”. The Eddington Factor method relates the mean intensity of the radiation field to the a value similar to the radiation pressure. The Eddington factor method allows one to calculate the radiation field using knowledge of the temperature distribution and opacity in the atmosphere. Once you have the mean intensity, the Feautrier method allows you to take the mean intensity and turn it into a quantity resembling the intensity along specific angles. This can then in turn be used to refine the values of the Eddington factor, and recompute the radiation field until it converges on a solution which is consistent with the temperature distribution.
A check can be made on the temperature distribution by comparing the actual flux as a function of depth with the expected flux. This allows one to correct the temperature distribution. With the corrected temperature distribution, you can recompute the radiation field as above.
My writeup (including graphs) is available by contacting me. If there is interest in seeing my code, post a comment.
One of the resources for my course on Stellar Atmospheres is this book by G. W. Collins II which is available online. Formerly a print book, it is now freely available online. It is a grad level textbook, but worth skimming at any rate.
The Fundamentals of Stellar Astrophysics (by G.W. Collins II)
