Calendar

Mar
15
Thu
Colloquium Thesis Proposal: Drew Chojnowski
Mar 15 @ 3:15 pm – 4:15 pm
Colloquium Thesis Proposal: Drew Chojnowski @ Domenici Hall 102

The Circumstellar Disks and Binary Companions of Be Stars

Drew Chojnowski, NMSU

Tremendous progress has been made over the past two decades toward understanding Be stars, but a number of key aspects of them remain enigmatic. The unsolved mysteries include identification of the mechanism responsible for disk formation, the reason this mechanism occasionally turns off or on unexpectedly, the source of viscosity in the circumstellar disks, and the cause of slowly precessing density perturbations in the disks of many or most Be stars. On a deeper level, the origin of Be stars’ near-critical rotation is unknown, with one possible explanation being spin-up due to interaction with a binary companion. A better understanding of these stars is needed, with a particular focus on high-mass binaries being warranted in the age of gravitational wave astronomy. In this dissertation, I will extend the knowledge and understanding of Be stars through a series of three projects. First, I will present and describe the largest ever homogeneous, spectroscopic sample of Be stars to date. I will then focus on investigation of a rare class of Be stars found in binary systems with hot, low mass companions. The second project will present detailed characterization and modeling of HD~55606, a newly discovered member of this class. Finally, I will discuss the results of spectroscopic monitoring of seven newly discovered systems and establish or place limits on the orbital parameters of the binary components.

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
13
Fri
Colloquium Thesis Proposal: Emma Dahl
Apr 13 @ 3:15 pm – 4:15 pm
Colloquium Thesis Proposal: Emma Dahl @ BX102

Colloquium Title

Emma Dahl, NMSU

Abstract text

May
9
Wed
Colloquium Thesis Proposal: Caitlin Doughty
May 9 @ 2:15 pm – 3:15 pm
Colloquium Thesis Proposal: Caitlin Doughty @ Science Hall 107

Metal Absorption in the Circumgalactic Medium During the Epoch of Reionization

Caitlin Doughty, NMSU

The characteristics of metal absorption arising from the circumgalactic medium of galaxies have been demonstrated to be related to conditions in the galaxy which sourced them, as well as to the ambient ultraviolet background. I propose a three- pronged thesis in order to better understand and utilize these relationships. First, I will explore whether the spectral energy distributions of binary stars, incorporated into a custom version of GADGET-3, can explain the discrepancy between observed and simulated absorber statistics. Second, I will study the relationship between neu- tral oxygen absorbers and the neutral hydrogen fraction in simulated quasar sight- lines and relate the results to observations of neutral oxygen at z ≥ 4.0. Third, I will study the relationships between the emissive properties of galaxies, stemming from their nebular gas, and the metal absorbers which they source. Taken as a whole, this thesis will improve the ability of cosmological simulations to reproduce realistic metal absorption, probe the local progress and topology of reionization, and under- stand what emissive galaxy traits we expect at z > 5 based on observations of metal absorbers.

Aug
16
Thu
ASTR 620 – Planetary Processes
Aug 16 @ 8:55 am – 10:10 am
Aug
21
Tue
ASTR 620 – Planetary Processes
Aug 21 @ 8:55 am – 10:10 am
Aug
23
Thu
ASTR 620 – Planetary Processes
Aug 23 @ 8:55 am – 10:10 am
Aug
24
Fri
Colloquium: Dawn Gelino (Host: Tom Harrison)
Aug 24 @ 3:15 pm – 4:15 pm
Colloquium: Dawn Gelino (Host: Tom Harrison) @ BX102

NASA, Exoplanets, and Life After NMSU

Dawn Gelino, NASA Exoplanet Science Institute, CalTech

Abstract:  Are you interested in learning more about the search for life in the Universe? Or perhaps you may be interested in being awarded time on 10 m telescopes for your science? Or maybe you are ready to learn more about prestigious NASA Postdoctoral Fellowships? This talk will touch on some recent and exciting results in the exoplanet field, as well as the different NASA HQ programs that I currently run for all of astrophysics (many of which may be helpful and applicable to YOU), and the path I took from NMSU to where I am now.

Aug
27
Mon
Planetary Group meeting
Aug 27 @ 2:00 pm – 3:00 pm
Aug
28
Tue
ASTR 620 – Planetary Processes
Aug 28 @ 8:55 am – 10:10 am