Calendar

Oct
16
Fri
Colloquium: Doug Biesecker
Oct 16 @ 3:15 pm – 4:15 pm
Colloquium: Doug Biesecker @ BX102

Why Space Weather Matters and How Forecasting Will Improve in the DSCOVR Era

Doug Biesecker, NOAA/NWS/Space Weather Prediction Center

Space Weather is a growing enterprise, with growing recognition of its importance inside and outside government.  The largest concern is with the electric power grid, but impacts to Global Positioning Systems (GPS) are also significant.  Other areas of impact include satellites and human space flight, and high frequency communication for aviation, mariners, and emergency responders, among many.  The NOAA National Weather Service’s Space Weather Prediction Center (SWPC) is the nation’s official source of space weather watches, warnings and alerts.  SWPC does this with a 24×7 staffed operation that monitors the Sun, solar wind, and geospace environment taking advantage of a broad suite of observations and models to provide the best forecasts possible.  In conjunction with the growing recognition of space weather, NOAA launched its first mission, the Deep Space Climate Observatory (DSCOVR), out of the Earth’s orbit to an orbit about the L1 Lagrange point.  This is also NOAA’s first satellite mission where space weather is the primary mission and DSCOVR marks the first of what is expected to be a long series of space weather monitoring satellites.  NOAA is also bringing numerical space weather models into the mix of models running on the nation’s supercomputers.  Numerical space weather models have demonstrated the ability to improve the onset time of space weather storms and will, for the first time, allow regional geomagnetic forecasting.  Instead of describing conditions on Earth with a single number, customers will have forecasts tailored to their location.

 

Oct
30
Fri
Colloquium: Sergio Rodriguez
Oct 30 @ 3:15 pm – 4:15 pm
Colloquium: Sergio Rodriguez @ BX102

BOSS DR12 survey: Clustering of galaxies and Dark Matter Haloes

Sergio Rodriguez, UAM, Madrid and Cal. Berkeley

BOSS SDSS-III is the largest redshift survey for the large scale structure and a powerful sample for the study of the low redshift Baryonic Acoustic Oscillations. We combine the features of the survey, such as, geometry, angular incompleteness and stellar mass incompleteness, with the BigMultiDark cosmological simulation to do a study of the distribution of galaxies in the dark matter halos. Using this large N-Body simulation and the halo abundance matching technique, we found a remarkably good agreement with the 2-point and 3-point statistics of the data.

Feb
12
Fri
Colloquium: Lauren Woolsey
Feb 12 @ 3:15 pm – 4:15 pm
Colloquium:  Lauren Woolsey @ BX102

Magnetic Influences on Coronal Heating and the Solar Wind

Lauren Woolsey, Harvard University

 

Abstract

The physical mechanism(s) that generate and accelerate the solar wind have not been conclusively determined after decades of study, though not for lack of possibilities. The long list of proposed processes can be grouped into two main paradigms: 1) models that require the rearranging of magnetic topology through magnetic reconnection in order to release energy and accelerate the wind and 2) models that require the launching of magnetoacoustic and Alfvén waves to propagate along the magnetic field and generate turbulence to heat the corona and accelerate the emanating wind. After a short overview of these paradigms, I will present my ongoing dissertation work that seeks to investigate the latter category of theoretical models and the role that different magnetic field profiles play in the resulting solar wind properties with Alfvén-wave-driven turbulent heating. I will describe the computer modeling in 1D and 3D that I have done of bundles of magnetic field (flux tubes) that are open to the heliosphere, and what our results can tell us about the influences of magnetic field on the solar wind in these flux tubes, including the latest time-dependent modeling that produces bursty, nanoflare-like heating. Additionally, I will present the latest results of our study of chromospheric network jets and the magnetic thresholds we are finding in magnetogram data.

Mar
4
Fri
Colloquium: Gail Zasowski (Host: Drew Chojnowski)
Mar 4 @ 3:15 pm – 4:15 pm
Colloquium:  Gail Zasowski  (Host: Drew Chojnowski) @ BX102

New Tools for Galactic Archaeology from the Milky Way

Gail Zasowski, John Hopkins University

One of the critical components for understanding galaxy evolution is understanding the Milky Way Galaxy itself — its detailed structure and chemodynamical properties, as well as fundamental stellar physics, which we can only study in great detail locally.  This field is currently undergoing a dramatic expansion towards the kinds of large-scale statistical analyses long used by the extragalactic and other communities, thanks in part to an enormous influx of data from space- and ground-based surveys.  I will describe the Milky Way and Local Group in the context of general galaxy evolution and highlight some recent developments in Galactic astrophysics that take advantage of these big data sets and analysis techniques.  In particular, I will focus on two diverse approaches: one to characterize the distribution and dynamics of the carbon-rich, dusty diffuse ISM, and one to map the resolved bulk stellar properties of the inner disk and bulge.  The rapid progress in these areas promises to continue, with the arrival of data sets from missions like SDSS, Gaia, LSST, and WFIRST.

May
31
Tue
Colloquium PhD Defense: Diane Feuillet
May 31 @ 3:00 pm – 4:00 pm
Colloquium PhD Defense: Diane Feuillet @ Dominici106

Ages and Abundance of Local Stellar Populations

Diane Feuillet, NMSU

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.

Mar
3
Fri
Colloquium: Bart De Pontieu
Mar 3 @ 3:15 pm – 4:15 pm
Colloquium: Bart De Pontieu @ BX 102

Interface Region Imaging Spectrograph Views of How the Solar Atmosphere is Energized

Dr. Bart De Pontieu, Lockheed Martin

At the interface between the Sun’s surface and million-degree outer atmosphere or corona lies the chromosphere. At 10,000K it is much cooler than the corona, but also many orders of magnitude denser. The chromosphere processes all magneto-convective energy that drives the heating of the million-degree outer atmosphere or corona, and requires a heating rate that is at least as large as that required for the corona. Yet many questions remain about what drives the chromospheric dynamics and energetics and how these are connected to the transition region and corona.

The Interface Region Imaging Spectrograph (IRIS) is a NASA small explorer satellite that was launched in 2013 to study these questions. I will review recent results from IRIS in which observations and models are compared to study the onset of fast magnetic reconnection in the solar atmosphere, the generation of violent jets and how they feed plasma into the hot corona, and the role of nanoflares in heating the corona.

Mar
10
Fri
Colloquium: Hazel Bain
Mar 10 @ 3:15 pm – 4:15 pm
Colloquium: Hazel Bain @ BX 102

Antarctic high altitude balloon observations of solar flares: Life and work on the ice

Dr. Hazel Bain, University of California, Berkeley

 

The Gamma-Ray Imager/Polarimeter for solar flares (GRIPS) instrument is a balloon-borne telescope designed to study particle acceleration in solar flares. The process through which stored magnetic energy is released and particles are accelerated to high energies in solar flares is not well understood. Hard x-rays and gamma-rays are direct signatures of these accelerated particles and can be used as a proxy to investigate particle acceleration mechanisms in these explosive events.

In the austral summer of 2016, GRIPS began its inaugural flight from NASA’s Long Duration Balloon (LDB) facility just outside McMurdo, Antarctica. During the 12 day flight, the balloon was carried around the Antarctic continent by the seasonal stratospheric polar vortex. At the end of the 2016 season, the data vaults were recovered however due to the lateness of the season a full recovery was scheduled for the following year.

In this talk I will discuss the GRIPS instrument design and science goals, the process of testing and integration leading up to a balloon launch, the inaugural flight and subsequent instrument recovery this year from the GRIPS landing site out in Antarctica’s “flat white”. I’ll also talk a little bit about life and work on the ice.

Apr
24
Mon
Pizza Lunch: Laurel Farris
Apr 24 @ 12:30 pm – 1:30 pm
Pizza Lunch: Laurel Farris @ AY 119

Determining the size of coronal bright points using cross-correlation methods

Laurel Farris

 

Dec
4
Mon
Pizza Lunch: Karen Kinemuchi
Dec 4 @ 12:30 pm – 1:30 pm
Pizza Lunch: Karen Kinemuchi @ AY 119

Life at Apache Point Observatory