Calendar

Sep
24
Mon
Pizza lunch: Drew Chojnowski
Sep 24 @ 12:30 pm – 1:30 pm
Pizza lunch: Drew Chojnowski @ AY 119

Ap Stars

Oct
8
Mon
Pizza lunch: Patrick Gaulme
Oct 8 @ 12:30 pm – 1:30 pm
Pizza lunch: Patrick Gaulme @ AY 119

Red giants, eclipsing binaries, and asteroseismology.

Patrick Gaulme, Max Planck Institute for Solar System Research

Nov
5
Mon
Pizza lunch: Heidi Sanchez
Nov 5 @ 12:30 pm – 1:30 pm
Pizza lunch: Heidi Sanchez @ AY 119

The Sunspot Solar Observatory Visitor Center

Heidi Sanchez, Sunspot Solar Observatory, NMSU

Nov
12
Mon
Pizza lunch: Nur Berdalieva and Shukur Kholikov
Nov 12 @ 12:30 pm – 1:30 pm
Pizza lunch: Nur Berdalieva and Shukur Kholikov @ AY 119

Past and Present Astronomy in Uzbekistan

Nur Berdalieva (Astronomical Institute of Uzbekistan) and Shukur Kholikov (National Solar Observatory)

Dec
3
Mon
Pizza lunch: Annie Hedlund, Alec Herczeg, and Julie Imig
Dec 3 @ 12:30 pm – 1:30 pm
Pizza lunch: Annie Hedlund, Alec Herczeg, and Julie Imig @ AY 119

ASTR 598

Jan
23
Wed
Colloquium Thesis Defense: Lauren Kahre
Jan 23 @ 3:00 pm – 4:00 pm
Colloquium Thesis Defense: Lauren Kahre

Extinction Mapping and Dust-to-Gas Ratios of Nearby Galaxies

Lauren Kahre, NMSU

We present a study of the dust{to{gas ratios in 31 nearby (D >
10 Mpc) galaxies. Using Hubble Space Telescope broad band WFC3/UVIS UV and
optical images from the Treasury program LEGUS (Legacy ExtraGalactic UV
Survey) combined with archival HST/ACS data, we correct thousands of
individual stars for extinction across these galaxies using an
isochrone-matching (reddening-free Q) method. We generate extinction maps
for each galaxy from the individual stellar extinctions using both
adaptive and fixed resolution techniques, and correlate these maps with
neutral HI and CO gas maps from literature, including The HI Nearby Galaxy
Survey (THINGS) and the HERA CO-Line ExtraGalactic Survey (HERACLES). We
calculate dust-to-gas ratios and investigate variations in the dust-to-gas
ratio with galaxy metallicity. We find a power law relationship between
dust-to-gas ratio and metallicity. The single power law is consistent with
other studies of dust-to-gas ratio compared to metallicity, while the
broken power law shows a significantly shallower slope for low metallicity
galaxies than previously observed. We find a change in the relation when
H_2 is not included. This implies that underestimation of N_H2 in
low-metallicity dwarfs from a too-low CO-to-H2 conversion factor X_CO
could have produced too low a slope in the derived relationship between
dust-to-gas ratio and metallicity. We also
compare our extinctions to those derived from fitting the spectral energy
distribution (SED) using the Bayesian Extinction and Stellar Tool (BEAST)
for NGC 7793 and and systematically lower extinctions from SED-fitting as
compared to isochrone matching. Finally, we compare our extinction maps of
NGC 628 to maps of the dust obtained via IR emission from Aniano et al.
(2012) and find a factor of 2 difference in dust-to-gas ratios determined
from the two maps, consistent with previous work.

Jan
25
Fri
Pizza Lunch Talk: Dale Frail
Jan 25 @ 11:30 am – 12:30 pm
Pizza Lunch Talk: Dale Frail @ AY 119

How to Write A Competitive Prize Postdoc Application

Dale Frail, NRAO

Feb
22
Fri
Pizza Lunch Talk: Takashi Sekii
Feb 22 @ 12:15 pm – 1:15 pm
Pizza Lunch Talk: Takashi Sekii @ AY 119

Title

Takashi Sekii, National Astronomical Observatory of Japan

Abstract

Mar
4
Mon
Pizza Lunch Talk: Mark Rutkowski
Mar 4 @ 12:30 pm – 1:30 pm
Pizza Lunch Talk: Mark Rutkowski @ AY 119

Ultraviolet Observations of Galaxies

Mark Rutkowski, Minnesota State Univeristy

Ultraviolet observations are essential for answering fundamental questions regarding the role and impact of galaxies in universe. I’ll discuss a number of past, ongoing, and future UV-optical-near IR high redshift surveys with which I am involved and the specific constraints the UV provides on these open questions. Specifically, I’ll highlight the utility of UV observations of starbursts and quiescent galaxies alike for constraining the history of reionization, hierarchical assembly, and (if there’s time) the cosmic history of metals.

Apr
15
Mon
Pizza lunch: Inclusive Astronomy
Apr 15 @ 12:30 pm – 1:30 pm
Pizza lunch: Inclusive Astronomy