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
9
Fri
Colloquium: Ben Weiner
Oct 9 @ 3:15 pm – 4:15 pm
Colloquium:  Ben Weiner @ BX102

Searching for Dwarf Satellites around Milky Way – Analog Galaxies with the SAGA survey

Ben Weiner, Steward Observatory

Dwarf satellites of massive galaxies are a probe of many issues in galaxy evolution and cosmology, including the nature of low-mass galaxies, star formation at early times, accretion into halos, and the abundance of low-mass dark matter halos. Much attention has been devoted to the number and nature of Milky Way and M31 dwarf satellites, especially the “missing satellites problem.” However, we know very little about dwarf satellites outside the Local Group below the mass of the LMC, and we don’t know if the MW and M31 satellite systems are typical. The SAGA (Satellites Around Galactic Analogs) survey collaboration aims to address this with both observational and theoretical studies of satellite abundances and properties around Milky Way analog central galaxies. I will present results from our MMT/Hectospec wide field spectroscopic surveys for satellites. We have surveyed the fields of several nearby galaxies that are similar to the Milky Way to detect and spectroscopically confirm dwarf satellites.  We find a range of numbers of satellites, suggesting that there is a significant variance in halo histories.  We also find that not all dwarf systems resemble the Milky Way and M31 systems. I will discuss these results and some of the implications on the life cycle of satellites that we can infer from satellite abundances and properties, including their images and spectra.

 

Mar
11
Fri
Colloquium Thesis Proposal: Alexander Thelen (Host: Nancy Chanover)
Mar 11 @ 2:00 pm – 3:00 pm
Colloquium Thesis Proposal:  Alexander Thelen  (Host: Nancy Chanover) @ BX102

The Chemical History and Evolution of Titan’s Atmosphere as Revealed by ALMA

 Alexander Thelen, NMSU

Saturn’s largest moon, Titan, possesses a substantial atmosphere containing significant minorities of nitrile and hydrocarbon species, predominantly due to the photodissociation of the major gases, N2 and CH4. Titan’s methane cycle, liquid lakes, and complex organic chemistry make it an intriguing target through its similarities to Earth and the allure of its astrobiological potential. Though the existence of heavy nitrile species – such as CH3C3N, HC5N, and C3H7CN – has been inferred through Cassini Ion and Neutral Mass Spectrometer (INMS) data, confirmation of these species has yet to be made spectroscopically. Other hydrocarbon species, such as C3H4 and C3H8 have been detected using Voyager’s Infrared Spectrometer (IRIS; Maguire et al., 1981) and later mapped by the Composite Infrared Spectrometer (CIRS; Nixon et al., 2013) onboard Cassini, but abundance constraints for these species in the mesosphere is poor. To fully understand the production of these species and their spatial distribution in Titan’s atmosphere, vertical abundance profiles must be produced to use with current photochemical models. Utilizing early science calibration images of Titan obtained with the Atacama Large Millimeter/Submillimeter Array (ALMA), Cordiner et al. (2014; 2015) determined the vertical distribution of various nitriles and hydrocarbons in Titan’s atmosphere, including at least one previously undetected molecule – C2H5CN. For my dissertation project, I will calibrate and model sub-millimeter emissions from molecules in Titan’s atmosphere, and quantify variations in the spatial distribution of various species throughout its seasonal cycle by utilizing high resolution ALMA data.  The main goals of this project are as follows:
1. To search for previously undetected molecules in Titan’s atmosphere through analysis of the existing public ALMA data, and/or through ALMA proposals of my own;
2. Constrain abundance profiles of detected molecular species, and provide upper abundance limits for those we cannot detect;
3. Map the spatial distribution of detected species in order to improve our understanding of Titan’s atmospheric transport and circulation;
4. Determine how these spatial distributions change over Titan’s seasonal cycle by utilizing multiple years of public ALMA data.
The majority of this work will employ the Non-linear Optimal Estimator for MultivariatE Spectral analySIS (NEMESIS) software package, developed by Oxford University (Irwin et al., 2008), to retrieve abundance and temperature information through radiative transfer models. These results will allow us to investigate the chemical evolution and history of Titan’s rich, pre-biotic atmosphere by providing valuable abundance measurements and constraints to molecular photochemical and dynamical models. We will compare our results with measurements made by the Cassini spacecraft, thereby enhancing the scientific return from both orbiter and ALMA datasets. The increased inventory of complex, organic molecules observable with ALMA’s sub-mm frequency range and high spatial resolution may also yield detections of species fundamental to the formation of living organisms, such as amino acids. Thus, by informing photochemical and dynamical models and increasing our known inventory of complex molecular species, we will also assess Titan’s potential habitability.

Apr
15
Fri
Colloquium: Warren Skidmore (Host: Jim Murphy)
Apr 15 @ 3:15 pm – 4:15 pm
Colloquium:  Warren Skidmore     (Host: Jim Murphy) @ BX102

The Thirty Meter Telescope:   The Next Generation Ground Based Optical/InfraRed Observatory

Dr. Warren Skidmore, Thirty Meter Telescope Corp.

 

Abstract: After a construction status update, I will describe how the telescope design was developed to support a broad range of observing capabilities and how the observatory is being engineered. I’ll discuss some of the observational capabilities that the Thirty Meter Telescope will provide and some of the areas of study that will benefit from the TMT’s capabilities, specifically synergistic areas with new and future proposed astronomical facilities. Finally I will describe the avenues through which astronomers can have some input in the planning of the project and potential NSF partnership, prioritizing the development of 2nd generation instruments and directing the scientific aims for the observatory.

Mar
13
Mon
Pizza Lunch: Jean McKeever
Mar 13 @ 12:30 pm – 1:30 pm
Pizza Lunch: Jean McKeever @ AY 119

Red Giants in Eclipsing Binary Systems

Jean McKeever

 

Oct
16
Mon
Pizza Lunch: Ken Naiff
Oct 16 @ 12:30 pm – 1:30 pm
Pizza Lunch: Ken Naiff @ AY 119

Dark Sky Images

Ken Naiff

Ken, an retired engineer, is a highly technically skilled and artistic
astrophotographer.  He will be sharing some of his work and elaborating on
the technical methods and processing techniques he applies to obtain his
unique and enhanced images.  You can see Ken’s work at:

https://darkskyimagesbyken.com/products