Sunset at the Apache Point Observatory

You can see the silhouette of the Sloan Digital Sky Survey (SDSS) telescope to the left, and the lights of Las Cruces, NM in the distance. Handheld smartphone picture with blurring effects provided by too much coffee.

NGC 6418 Reverberation: The Poster

I just learned that Michael Richmond has made Billy Vasquez' AAS poster available here.

A syllabus appears

Astrophysics students: a syllabus has appeared for ASTR/PHYS 301 on moodle.bucknell.edu. There will be minor changes between now and the end of the week, but more importantly I haven't figured own when I should schedule office hours yet. We'll talk about the best time for office hours during our first class.

Let me know if you cannot access the Moodle page; it's possible that I forgot to set some hidden, virtual toggle.

Right now the Moodle page is available only to students registered. This restriction is necessary to protect fair-use, copyrighted material. I'm happy to register guests who might be interested; please e-mail a request!

Reverberation Mapping of the Dusty Torus of AGN NGC 6418

On Tuesday Jan 7, +Billy Vazquez (RIT) presented his monitoring study of NGC 6418 at the +American Astronomical Society meeting in Washington DC. I encourage everyone to hop in a time machine and go visit his poster.

It's a neat result. NGC 6418 is a relatively low luminosity active galaxy, which means that it harbors an accretion disk that gradually feeds a supermassive black hole. We monitored the accretion disk with visible light observations, and we simultaneously monitored the surrounding dusty torus with +Spitzer Space Telescope infrared observations. The infrared measurements have a relatively rapid cadence of 3 days between observations (for my part, I was responsible for setting up these infrared observations).

Billy found that the infrared signal lags the visible light signal by 30-40 days, which implies that the size of the dusty region is around 30-40 light days, or about 200 times the semi-major axis of Neptune's orbit in our own solar system. Since NGC 6418 is so far away, we wouldn't be able to take a clear picture of the dusty region, although infrared interferometry might have a shot at confirming the size. The apparent size of the dusty region is roughly equivalent to a penny viewed from a distance of one earth diameter.

Teaching Schedule, Spring 2014

ASTR/PHYS 301: Astrophysics. My current understanding is that the class runs MWF 11 - 11:50 AM. The textbook is Carroll & Ostlie, An Introduction to Modern Astrophysics, 2nd Edition (ISBN 0-8053-0402-9). It's the big orange book.