Jan. 20

Tinsley Visiting Scholar: Planetary Group

"Habitability of Planets Orbiting M Dwarfs"

abstract

Rory Barnes

University of Washington

host: Mike Endl

Jan. 27

"The Elusive and Ionized Gas Surrounding the Magellanic System"

abstract

Kathleen Barger

Texas Christian University

host: Cyndi Froning

Feb. 3

"Probing the Nature of Accretion and Planet Formation in Protoplanetary Disks: Connecting Theory with ALMA Observations"

abstract

Jacob B. Simon

Southwest Research Institute (SwRI)

host: Neal Evans

Feb. 10

"The Large Reservoirs of Gas Around Galaxies"

abstract

Jessica Werk

UCO/Lick Observatory

host: Volker Bromm

Feb. 12
Thursday

Special Colloquium: "Insights into Galaxy Formation from z=15 to the Present Day"

abstract

Peter Behroozi

Space Telescope Science Institute (STScI)

host: John Kormendy

Feb. 17

"Towards a Complete Theory of Lyman-Alpha Transfer in and around Galaxies"

abstract

Mark Dijkstra

University of Oslo: Institute of Theoretical Astrophysics

host: Steve Finkelstein

Feb. 19
Thursday

Special Colloquium: "Three Problems in Trying to Form Galaxies (and how ISM Physics can Save Us)"

abstract

Desika Narayanan

Haverford College

host: Chris Sneden

Feb. 24

"The Local Universe as a Cosmology Laboratory"

abstract

Michael Boylan-Kolchin

University of Maryland

host: Volker Bromm

Feb. 26
Thursday

Special Colloquium: "New Tools for Galactic Archaeology from the Milky Way"

abstract

Gail Zasowski

Johns Hopkins University

host: Adam Kraus

Mar. 3

"Massive Galaxy Growth since Cosmic Noon"

abstract

Stijn Wuyts

Max Planck Institut fur Extraterrestrische Physik

host: Chris Sneden

Mar. 10

Tinsley Visiting Professor

"David vs. Goliath: Exploiting the Black Hole Mass Scale to Better Constrain Accretion Physics"

abstract

Sera Markoff

University of Amsterdam

host: Pawan Kumar

Mar. 17

Spring Break: March 16 - 20: no Colloquium being held this week.

Mar. 24

"MOSFIRE: the Multi-Object Spectrometer for Infrared Exploration at Keck Observatory"

abstract

Ian McLean

University of California, Los Angeles

host: Gregory Mace

Mar. 31

Tinsley Visiting Scholar: Stars Group

"SPHERE: the New High-contrast Imager for the ESO-VLT"

abstract

Raffaele Gratton

INAF - Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, Italy

host: Chris Sneden

Apr. 7

No talk scheduled.

Apr. 14

"Star-Formation Driven Molecular Superwinds as Understood from the Two Nearest Starburst Galaxies (and a Small Survey)"

abstract

Adam Leroy

Ohio State University

host: Neal Evans

Friday
12 noon
Apr. 17

Qualifying Exam/2nd-Year Defense

"Chemical Analyses of Metal-Poor Stars: A New Approach"

abstract

Marc Schaeuble

University of Texas at Austin

Apr. 21

"Tracking Planet Footprints in Dusty Disks"

abstract

Catherine Espaillat

Boston University

host: Adam Kraus

Monday
12 noon
Apr. 27

Qualifying Exam/2nd-Year Defense

"Connecting the Dots: Tracking Galaxy Evolution at 3 <= z <= 7 using Fixed Cumulative Number Density in SPH Simulations"

abstract

Jason Jaacks

University of Texas at Austin

Apr. 28

Tinsley Visiting Scholar: Extragalactic Group

"Early Galaxies: Alive, Dead, Transitioning and/or Active"

abstract

Stijn Wuyts

Max Planck Institut fur Extraterrestrische Physik

host: Shardha Jogee

Wed.
3 PM
Apr. 29

PhD Defense

"Innovative Technologies for - and Observational Studies of - Star and Planet Formation"

The lowest mass objects in nearby star forming regions now accessible to spectroscopy are in the sub-brown dwarf regime, with estimated masses comparable to the masses of extrasolar planets and bordering the threshold of opacity limited fragmentation. We confirm and characterize, using R=2000 near-infrared spectroscopy, 17 candidate young substellar objects in nearby star forming regions. Using deep optical, near-infrared, and mid-infrared photometry, we have searched an off-core region of the nearby ~1 Myr Ophiuchus star forming cluster for candidate young stars and brown dwarfs. Multi-object I-band spectroscopy of 419 candidates reveals 12 new young stars and brown dwarfs. Ten of these have no evidence for mid-IR emission from 3.6 to 8.0 micron. The other two are indicative of edge-on disks, based on their mid-infrared slopes rising with wavelength. The disk fraction for spectral types M4 and later towards this region of Ophiuchus is 33%, lower than the typical disk fraction of 1-3 Myr clusters.

I also summarize the optical design, fabrication, and performance of silicon diffractive optics for astronomical spectrographs. The optical devices include diffraction-limited, high-throughput silicon grisms for JWST-NIRCam. These grisms served as pathfinders to Silicon immersion gratings, which offer size and cost savings for high-resolution near-infrared spectrographs. I demonstrate the production and optical evaluation of the immersion grating that enabled IGRINS at the McDonald Observatory. This grating provides spectral resolution R=40,000 over the H- and K- near-infrared band atmospheric windows (1.5-2.5 micron). Electron-beam lithography offers much higher precision over contact mask photolithography for the production of Si immersion gratings. Using electron-beam lithography, I designed, fabricated, and tested diffraction-limited Si immersion gratings over a 30 x 100 mm beam. These prototypes are stepping stones to monolithic Si gratings for iSHELL and GMTNIRS. The monolithic design of Si immersion gratings presents a limitation for scaling up the grating size, since existing fabrication equipment cannot handle monolithic silicon pucks. The size limitation can be overcome by direct-bonding Si substrates to optical prisms. I demonstrate a technique to measure interfacial gaps as small as 14 nm between the bonding interface. Gaps this small produce 0.2% transmission loss. These technologies will enable the direct measurement of the atmospheric properties of extrasolar planets in the next decade.

close

Michael Gully-Santiago

University of Texas at Austin

Thurs.
11 AM
Apr. 30
RLM 15.202A

Qualifying Exam/2nd-Year Defense

"External Inverse-Compton Emission from Jetted Tidal Disruption Events"

abstract

Wenbin Lu

University of Texas at Austin

Fri.
1 PM
May 1

PhD Defense

"On the Nature of Emission from Relativistic Jets"

abstract

Patrick Crumley

University of Texas at Austin

Fri.
2 PM
May 1

Qualifying Exam/2nd-Year Defense

"The Structure of Class 0 Protostars: BHR71 in Herschel View"

abstract

Yao-Lun Yang

University of Texas at Austin

Mon.
10 AM
May 4

Qualifying Exam/2nd-Year Defense

"Do Metal-Polluted Stars of the ZZ Ceti Instability Strip Have a Distinct Asteroseismic Signature?"

abstract

Kevin Jumper

University of Texas at Austin

Mon.
Noon
May 4

Qualifying Exam/2nd-Year Defense

"Peering Inside Galaxies in the First Two Billion Years"

abstract

Intae Jung

University of Texas at Austin

May 5

"Signatures of Neutron Star Mergers"

abstract

Brian Metzger

Columbia University

host: Pawan Kumar