Calendar

Sep
21
Fri
Astro-ph Discussion
Sep 21 @ 11:30 am – 12:00 pm
Colloquium: Dave Thilker (Host: Rene Walterbos)
Sep 21 @ 3:15 pm – 4:15 pm
Colloquium: Dave Thilker (Host: Rene Walterbos) @ BX102

Fresh Perspectives on Star Formation from LEGUS, the Legacy ExtraGalactic Ultraviolet Survey

David Thilker, Johns Hopkins University

The Legacy ExtraGalactic Ultraviolet Survey (LEGUS) was a Cycle 21 Large Treasury HST program which obtained ~parsec resolution NUV- to I-band WFC3 imaging for 50 nearby, representative star-forming Local Volume galaxies, with a primary goal of linking the scales of star formation from the limit of individual stars, to clusters and associations, eventually up through the hierarchy to giant star forming complexes and galaxy-scale morphological features.

I will review the basics of the survey, public data products and science team results pertaining to clusters and the field star hierarchy.  I will then describe work to optimize photometric selection methods for massive main sequence O star candidates and LBV candidates, in the former case establishing a means to statistically constrain the fraction of O stars in very isolated locales.  I will introduce new ideas on how to quantify the complex spatio-temporal nature of hierarchical star formation using multi-scale clustering methods. The first steps of this work have yielded a landmark OB association database for 36 LEGUS target fields (in 28 of the nearest available galaxies), with tracer stellar populations selected and interpreted uniformly.  I will finish with discussion of a pilot HST program to demonstrate remarkably increased survey efficiency of WFC3 UV imaging enabled by use of extra-wide (X) filter bandpasses.  Such efficiency is required as we move beyond LEGUS and begin to rigorously explore low surface brightness star-forming environments where canonical results for the IMF and cluster formation efficiency are increasingly called into question.

 

Sep
24
Mon
ASTR 545 – Stellar Spectroscopy
Sep 24 @ 11:00 am – 12:15 pm
Pizza lunch: Drew Chojnowski
Sep 24 @ 12:30 pm – 1:30 pm
Pizza lunch: Drew Chojnowski @ AY 119

Ap Stars

Planetary Group meeting
Sep 24 @ 2:00 pm – 3:00 pm
Astr110 Observatory
Sep 24 @ 9:00 pm – 10:00 pm
Sep
25
Tue
ASTR 620 – Planetary Processes
Sep 25 @ 8:55 am – 10:10 am
ASTR 555 – Galaxies I
Sep 25 @ 11:45 am – 1:00 pm
Machine Learning Cafe
Sep 25 @ 2:00 pm – 3:00 pm
Society of Astronomy Students Meeting
Sep 25 @ 4:00 pm – 5:00 pm