Calendar

Nov
30
Mon
Pizza Lunch: Ethan Dederick
Nov 30 @ 12:30 pm – 1:30 pm
Pizza Lunch: Ethan Dederick

598 Research

Apr
1
Fri
Colloquium: Hwiyun Kim (Host: Rene Walterbos)
Apr 1 @ 3:15 pm – 4:15 pm
Colloquium:  Hwiyun Kim     (Host: Rene Walterbos) @ BX102

High Resolution Spectroscopy with Immersion Grating Infrared Spectrometer (IGRINS)

Hwihyun Kim, KASI/UT Austin

 

The Immersion Grating Infrared Spectrometer (IGRINS) is a revolutionary instrument that exploits broad spectral coverage at high-resolution (R=45,000) in the near-infrared. IGRINS employs a silicon immersion grating as the primary disperser of the white pupil, and volume-phase holographic gratings cross-disperse the H and K bands onto Teledyne Hawaii-2RG arrays. IGRINS provides simultaneous wavelength coverage from 1.45 – 2.45 microns in a compact cryostat. I will summarize the performance and various science programs of IGRINS since commissioning in Summer 2014. With IGRINS we have observed such as Solar System objects, nearby young stars, star-forming regions like Taurus and Ophiuchus, the Galactic Center, and planetary nebulae.

The second half of my talk will be focused on the study of ionized and neutral gas in an ultracompact HII region Monoceros R2. We obtained the IGRINS spectra of Mon R2 to study the kinematic patterns in the areas where ionized and molecular gases interact. The position-velocity maps from the IGRINS spectra demonstrate that the ionized gases (Brackett and Pfund series, He and Fe emission lines;Δv ≈ 40km/s) flow along the walls of the surrounding clouds. This is consistent with the model by Zhu et al. (2005, 2008). In the PV maps of the H2 emission lines there is no obvious motion (Δv < ~10km/s) of the molecular hydrogen right at the ionization boundary. This implies that the molecular gas is not taking part in the flow as the ionized gas is moving along the cavity walls.

May
2
Mon
Pizza Lunch: Agnar Hall 598
May 2 @ 12:30 pm – 1:30 pm
May
9
Mon
Pizza Lunch: Laurel Farris 598
May 9 @ 12:30 pm – 1:30 pm
Pizza Lunch: Laurel Farris 598

Laurel Farris 598

Mar
29
Thu
Colloquium (Joint with Physics): Jim Fuller (Host: Ethan Dederick)
Mar 29 @ 4:00 pm – 5:00 pm
Colloquium (Joint with Physics): Jim Fuller (Host: Ethan Dederick) @ Gardiner Hall 230

Surprising Impacts of Gravity Waves

Jim Fuller, Caltech

Gravity waves are low frequency fluid oscillations restored by buoyancy forces in planetary and stellar interiors. Despite their ubiquity, the importance of gravity waves in evolutionary processes and asteroseismology has only recently been appreciated. For instance, Kepler asteroseismic data has revealed gravity modes in thousands of red giant stars, providing unprecedented measurements of core structure and rotation. I will show how gravity modes (or lack thereof) can also reveal strong magnetic fields in the cores of red giants, and I will demonstrate that strong fields appear to be common within “retired” A stars but are absent in their lower-mass counterparts. In the late phase evolution of massive stars approaching core-collapse, vigorous convection excites gravity waves that can redistribute huge amounts of energy within the star. I will present preliminary models of this process, showing how wave energy redistribution can drive outbursts and enhanced mass loss in the final years of massive star evolution, with important consequences for the appearance of subsequent supernovae.
Apr
22
Mon
Pizza lunch: Sarah Kovac/David DeColibus
Apr 22 @ 12:30 pm – 1:30 pm
Pizza lunch: Sarah Kovac/David DeColibus @ AY 119

ASTR 598

Apr
29
Mon
Pizza lunch: Kristen Luchsinger
Apr 29 @ 12:30 pm – 1:30 pm
Pizza lunch: Kristen Luchsinger @ AY 119

ASTR 598

Dec
2
Mon
Pizza lunch: ASTR 598 (Farhan and Oana)
Dec 2 @ 12:30 pm – 1:30 pm
Pizza lunch: ASTR 598 (Farhan and Oana) @ AY 119

ASTR 598

Farhan Hasan and Oana Vesa

Dec
4
Wed
Pizza lunch: ASTR 598 (Ali and Matt)
Dec 4 @ 12:00 pm – 1:00 pm
Pizza lunch: ASTR 598 (Ali and Matt) @ AY 119

ASTR 598

Ali Hyder and Matt Varakian

Dec
9
Mon
Pizza lunch: ASTR 598 (Minje)
Dec 9 @ 12:30 pm – 1:15 pm
Pizza lunch: ASTR 598 (Minje) @ AY 119

ASTR 598

Minje Boem