Calendar

Nov
6
Fri
Colloquium: John Wisniewski
Nov 6 @ 3:15 pm – 4:15 pm
Colloquium:  John Wisniewski @ BX102

Diagnosing the SEEDS of Planet Formation

John Wisniewski, University of Oklahoma

Circumstellar disks provide a useful astrophysical diagnostic of the formation and early evolution of exoplanets. It is commonly believed that young protoplanetary disks serve as the birthplace of planets, while older debris disks can provide insight into the architecture of exoplanetary systems. In this talk, I will discuss how one can use high contrast imaging techniques to spatially resolve nearby circumstellar disk systems, and how this imagery can be used to search for evidence of recently formed planetary bodies. I will focus on results from the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) project, as well as some ongoing follow-up work.

Sep
20
Tue
Colloquium Thesis Proposal: Ethan Dederick
Sep 20 @ 3:00 pm – 4:00 pm
Colloquium Thesis Proposal: Ethan Dederick @ Science Hall 310

Utilizing Planetary Oscillations to Constrain the Interior Structure of the Jovian Planets

Ethan Dederick

Seismology has been the premier tool of study for understanding the
interior structure of the Earth, the Sun, and even other stars. Yet in this
thesis proposal, we wish to utilize these tools to understand the interior
structure of the Jovian planets, Saturn in particular. Recent observations
of spiral density structures in Saturn’s rings caused by its oscillations
have provided insight into which modes exist within Saturn and at what
frequencies. Utilizing these frequencies to compare to probable mode can-
didates calculated from Saturn models will also us to ascertain the interior
profiles of state variables such as density, sound speed, rotation, etc. Using
these profiles in a Saturn model, coupled with tweaking the interior struc-
ture of the model, i.e. the inclusion of stably stratified regions, should
allow us to explain which modes are responsible for the density structures
in the rings, as well as predict where to look to find more such structures.
In doing so, we will not only have a much greater understanding of Sat-
urn’s interior structure, but will have constructed a method that can also
be applied to Jupiter once observations of its mode frequencies become
available. In addition, we seek to explain if moist convection on Jupiter is
responsible for exciting its modes. We aim to do this by modeling Jupiter
as a 2D harmonic oscillator. By creating a resonance between moist con-
vective storms and Jovian modes, we hope to match the expected mode
energies and surface displacements of Jupiter’s oscillations.

Nov
11
Fri
Colloquium: Amy Simon (Host: Nancy Chanover)
Nov 11 @ 3:15 pm – 4:15 pm
Colloquium: Amy Simon (Host: Nancy Chanover) @ Biology Annex 102

Outer Planets Update

Dr. Amy Simon, NASA

The Hubble Outer Planet Atmospheres Legacy (OPAL) program is a yearly program for observing each of the outer planets over two full rotations. Observations began with Uranus in 2014, adding Neptune and Jupiter in 2015 (Saturn will be included in 2018, after the end of the Cassini mission). These observations have provided interesting new discoveries in their own right, but are also now being combined with observations from a number of facilities, including NASA’s IRTF, Keck, the VLA, as well as the Kepler and Spitzer missions to further expand the breadth of science they contain.  This talk will cover the latest observations for each of these planets and what we are learning from these data sets.

 

Sep
1
Fri
Colloquium: Isak Wold (Host: Moire Prescott)
Sep 1 @ 3:15 pm – 4:15 pm
Colloquium: Isak Wold (Host: Moire Prescott) @ BX102

A Faint Flux-Limited LAE Sample at z = 0.3

Isak Wold, UT Austin

Observational surveys of Lya emitters (LAEs) have proven to be an efficient method to identify and study large numbers of galaxies over a wide redshift range. To understand what types of galaxies are selected in LAE surveys – and how this evolves with redshift – it is important to establish a low-redshift reference sample that can be directly compared to high-redshift samples.  The lowest redshift where a direct Lya survey is currently possible is at a redshift of z~0.3 via the Galaxy Evolution Explorer (GALEX ) FUV grism data. Using the z~0.3 GALEX sample as an anchor point, it has been suggested that at low redshifts high equivalent width (EW) LAEs become less prevalent and that the amount of escaping Lya emission declines rapidly.  A number of explanations for these trends have been suggested including increasing dust content, increasing neutral column density, and/or increasing metallicity of star-forming galaxies at lower redshifts. However, the published z~0.3 GALEX sample is pre-selected from bright NUV objects.  Thus, objects with strong Lya emission but faint continuum (high-EW LAEs) could be missed.  In this talk, I will present my efforts to re-reduce the deepest archival GALEX FUV grism data and obtain a sample that is not biased against high-EW LAEs.  I will discuss the implications of this new sample on the evolutionary trends listed above.