Calendar

Aug
28
Fri
Colloquium Thesis Proposal: Laura Mayorga
Aug 28 @ 3:15 pm – 4:15 pm
Colloquium Thesis Proposal: Laura Mayorga @ BX102

Probing Exoplanet Atmospheric Properties from Phase Variations and Polarization

Laura Mayorga, NMSU

The study of exoplanets is evolving past simple transit and Doppler method discovery and characterization. One of the many goals of the upcoming mission WFIRST-AFTA is to directly image giant exoplanets with a coronagraph. We undertake a study to determine the types of exoplanets that missions such as WFIRST will encounter and what instruments these missions require to best characterize giant planet atmospheres. We will first complete a benchmark study of how Jupiter reflects and scatters light as a function of phase angle. We will use Cassini flyby data from late 2000 to measure Jupiter’s phase curve, spherical albedo, and degree of polarization. Using Jupiter as a comparison, we will then study a sample of exoplanet atmosphere models generated to explore the atmospheric parameter space of giant planets and estimate what WFIRST might observe. Our study will provide valuable refinements to Jupiter-like models of planet evolution and atmospheric composition. We will also help inform future missions of what instruments are needed to characterize similar planets and what science goals will further our knowledge of giant worlds in our universe.

Oct
2
Fri
Colloquium: Rodolfo Montez Jr.
Oct 2 @ 3:15 pm – 4:15 pm
Colloquium: Rodolfo Montez Jr. @ BX102

Insights into Binary Stars, Stellar Winds, and Astrophysical Plasmas from X-ray Observations of Planetary Nebulae

Rodolfo Montez Jr., Vanderbilt University

 

Oct
12
Mon
Pizza Lunch: Paul Beck (Saclay)
Oct 12 @ 12:30 pm – 1:30 pm
Pizza Lunch: Paul Beck (Saclay)

Oscillating red giant stars in eccentric binary systems

Oct
26
Mon
Pizza Lunch: Kyle Uckert and Nancy Chanover
Oct 26 @ 12:30 pm – 1:30 pm
Pizza Lunch: Kyle Uckert and Nancy Chanover

Integration of an IR spectrometer with a rock climbing robot

Dec
4
Fri
Colloquium: Brian Jackson
Dec 4 @ 3:15 pm – 4:15 pm
Colloquium:  Brian Jackson @ BX102

On the Edge: Exoplanets with Orbital Periods Shorter Than a Peter Jackson Movie

Brian Jackson, Boise State Univeristy

From wispy gas giants to tiny rocky bodies, exoplanets with orbital periods of several days and less challenge theories of planet formation and evolution. Recent searches have found small rocky planets with orbits reaching almost down to their host stars’ surfaces, including an iron-rich Mars-sized body with an orbital period of only four hours. So close to their host stars that some of them are actively disintegrating, these objects’ origins remain unclear, and even formation models that allow significant migration have trouble accounting for their very short periods. Some are members of multi-planet system and may have been driven inward via secular excitation and tidal damping by their sibling planets. Others may be the fossil cores of former gas giants whose atmospheres were stripped by tides.

In this presentation, I’ll discuss the work of our Short-Period Planets Group (SuPerPiG), focused on finding and understanding this surprising new class of exoplanets. We are sifting data from the reincarnated Kepler Mission, K2, to search for additional short-period planets and have found several new candidates. We are also modeling the tidal decay and disruption of close-in gaseous planets to determine how we could identify their remnants, and preliminary results suggest the cores have a distinctive mass-period relationship that may be apparent in the observed population. Whatever their origins, short-period planets are particularly amenable to discovery and detailed follow-up by ongoing and future surveys, including the TESS mission.

Feb
5
Fri
Colloquium: Steve Finkelstein (Host: Kristian Finlator)
Feb 5 @ 3:15 pm – 4:15 pm
Colloquium:  Steve Finkelstein   (Host: Kristian Finlator) @ BX102

Galaxy Evolution during the Epoch of Reionization

 Steve Finkelstein,  University of Texas at Austin

 

                       Abstract: The advent of the Wide Field Camera 3 on the Hubble Space Telescope has heralded a new era in our ability to study the earliest phases of galaxy formation and evolution.  The number of candidates for galaxies now known at redshifts greater than six has grown to be in the thousands.  This allows us to move beyond mere counting of galaxies, to endeavor to understand the detailed physics regulating the growth of galaxies.  I will review the recent progress our group in Texas has made in this arena using the exquisite datasets from the CANDELS and Frontier Fields programs.  Specifically, our detailed new measurements of both the evolution of the stellar mass function and rest-frame UV luminosity function now allow us to probe the effect of feedback on low-mass galaxies, the star-formation efficiency in high-mass galaxies, and the contribution of galaxies to the reionization of the universe.  Our most recent result comes from the Frontier Fields, where we have used an advanced technique to remove the light from the cluster galaxies to uncover z > 6 galaxies as faint as M_UV=-13.  Our updated luminosity functions show no sign of a turnover down to these extremely faint levels, providing the first empirical test of reionization models which require such faint galaxies, and is in modest tension with simulations which predict a turnover at brighter levels.   I will also discuss our spectroscopic followup efforts, which have yielded two of the four highest redshift confirmed galaxies, and also provide further insight into reionization, by the scattering of Lyman alpha emission by neutral gas in the intergalactic medium.  I will conclude with a look ahead to the problems we can expect to tackle with ALMA, JWST, and even more future facilities.

Apr
8
Fri
Colloquium PhD Defense: Meredith Rawls
Apr 8 @ 3:00 pm – 4:00 pm
Colloquium PhD Defense: Meredith Rawls @ BX102

Red Giants in Eclipsing Binaries as a Benchmark for Asteroseismology

Meredith Rawls, NMSU

Sep
20
Wed
Colloquium PhD Defense: Jean McKeever
Sep 20 @ 3:00 pm – 4:15 pm
Colloquium PhD Defense: Jean McKeever @ Business College 103

Asteroseismology of Red Giants: The Detailed Modeling of Red Giants in Eclipsing Binary Systems

Jean McKeever, NMSU

Asteroseismology is an invaluable tool that allows one to peer into the inside of a star and know its fundamental stellar properties with relative ease. There has been much exploration of solar-like oscillations within red giants with recent advances in technology, leading to new innovations in observing. The Kepler mission, with its 4-year observations of a single patch of sky, has opened the floodgates on asteroseismic studies. Binary star systems are also an invaluable tool for their ability to provide independent constraints on fundamental stellar parameters such as mass and radius. The asteroseismic scaling laws link observables in the light curves of stars to the physical parameters in the star, providing a unique tool to study large populations of stars quite easily. In this work we present our 4-year radial velocity observing program to provide accurate dynamical masses for 16 red giants in eclipsing binary systems. From this we find that asteroseismology overestimates the mass and radius of red giants by 15% and 5% respectively. We further attempt to model the pulsations of a few of these stars using stellar evolution and oscillation codes. The goal is to determine which masses are correct and if there is a physical cause for the discrepancy in asteroseismic masses. We find there are many challenges to modeling evolved stars such as red giants and we address a few of the major concerns. These systems are some of the best studied systems to date and further exploration of their asteroseismic mysteries is inevitable.

 

Jan
24
Wed
Colloquium Thesis Proposal: Laurel Farris
Jan 24 @ 2:30 pm – 3:30 pm
Colloquium Thesis Proposal: Laurel Farris @ Science Hall, Room 110

Characterizing the oscillatory response of the chromosphere during solar flares

Laurel Farris; NMSU Astronomy Department

Quasi-periodic pulsations (QPPs) are observed in the emission of solar flares over a wide range of wavelengths,

particularly in the radio and hard x-ray regimes where non-thermal emission dominates. These pulsations are

considered to be an intrinsic feature of flares, yet the exact mechanism that triggers them remains unclear.

There have been reports of an increase in the oscillatory power at 3-minute periods (the local acoustic

cutoff frequency) in the solar chromosphere associated with flaring events. I propose to investigate the

chromospheric response to flares by inspecting the spatial and temporal onset and evolution of the 3-minute

oscillatory power, along with any QPP patterns that may appear in chromospheric emission. The analysis

will be extended to multiple flares, and will include time before, during, and after the main event. To test

initial methods, the target of interest was the well-studied 2011 February 15 X-class flare. Data from two

instruments on board the Solar Dynamics Observatory (SDO) were used in the preliminary study, including

continuum images from the Helioseismic and Magnetic Imager (HMI) and UV images at 1600 and 1700

Angstroms from the Atmospheric Imaging Assembly (AIA). Later, spectroscopic data from the Interface

Region Imaging Spectrometer (IRIS) will be used to examine velocity patterns in addition to intensity.