Thursday, March 1, 2018 - 3:00pm to 4:00pm  ·  Space Science Seminar
Dr. Kris Klein, University of Michigan

Abstract:  Instabilities help regulate the dynamic behavior of many collisionless plasma systems, including those of interest to the plasma, space, solar, and astrophysics communities. Typical stability studies focus on the parametric behavior of specific unstable modes or a single free-energy source. In this work, we employ for the first time on a random statistical set of solar wind observations a method that determines stability allowing for all sources of free energy, known as Nyquist's instability criterion.

Tuesday, February 6, 2018 - 2:30pm to 3:30pm  ·  Space Science Seminar
Dr. Regina Caputo

Abstract: The recent joint detection of gravitational waves from a binary neutron star merger and an associated short gamma-ray burst (GRB) has given rise to a new branch of multi-messenger astrophysics. Upgrades to the current LIGO/Virgo facilities, and the eventual addition of more gravitational wave observatories, will expand the detection horizon. New gamma-ray instruments are needed in both the near-term to complement current instruments, and in the long-term to insure that future joint detections will be possible. One instrument, BurstCube, is set to launch in 2021.

Thursday, February 1, 2018 - 1:30pm to 2:30pm  ·  Space Science Seminar
Dr. Joshua Schlieder (NASA / Goddard Space Flight Center)

Abstract: NASA's Kepler mission revolutionized our understanding of the frequency and diversity of exoplanets. Despite observing relatively few low-mass M dwarf stars, a key result from Kepler was that M dwarfs frequently host small Earth-like planets. With the failure of two reaction wheels, the Kepler mission ended and was reborn as K2, an ecliptic plane survey with ~80 day observing campaigns. I will recount the story of planets orbiting low-mass stars from Kepler, describe the transition to K2, and highlight key discoveries made in its first 3 years.

Tuesday, January 30, 2018 - 2:30pm to 3:30pm  ·  Space Science Seminar
Dr. Nahee Park, Wisconsin IceCube Particle Astrophysics Center

Abstract: Cosmic rays, high energy particles originating from outside of the solar system, are believed to be dominated by particles from our Galaxy at least up to the energy of 10^15 eV. Recent precise measurements of leptons and light nuclei below 1 TeV/nucleon by the satellite experiments PAMELA and AMS-02 are challenging the classical paradigm of Galactic cosmic-ray astrophysics. It is essential to understand the propagation of these particles to study the origins of discrepancies with the classical models.

Friday, January 26, 2018 - 2:30am to 3:30am  ·  Space Science Seminar
Dr. Jaclyn Sanders, Syracuse University

Abstract: The Laser Interferometer Gravitational-Wave Observatory (LIGO) observation of binary neutron star GW170817 initiated the first successful joint electromagnetic and gravitational wave observations. The future success of multi-messenger observations depends on the noise properties and sensitivity of gravitational wave interferometers. The goal of interferometer research and development is to improve detector sensitivity, allowing for more detections with higher signal-to-noise ratios and expanding the scope of astrophysical investigations.

Tuesday, January 23, 2018 - 2:30pm to 3:30pm  ·  Space Science Seminar
Dr. Fabian Kislat , Washington University

The MeV energy range is one of the astrophysically least-explored energy bands in the electromagnetic spectrum. By mapping nuclear lines in the range from several hundred keV to a few MeV, regions of element formation in the Galaxy can be studied. Furthermore, MeV observations are ideal to study Gamma-Ray Bursts (GRBs). The recent discovery of a coincidence between a gravitational wave signal and a GRB has triggered renewed interest in such observations.

Friday, December 1, 2017 - 2:00pm to 3:00pm  ·  Space Science Seminar
Harald Kucharek UNH

Abstract: Remote sensing IBEX observations of the interstellar gas flow in the inner heliosphere provide the most detailed information about the physical conditions of the surrounding interstellar medium and the interaction of this flow with the heliosheath. An excellent diagnostic tool to probe this interaction is the secondary component of the interstellar neutral gas flow that originates from charge exchange between primary interstellar neutrals and the plasma at the heliosheath.

Tuesday, November 21, 2017 - 11:00am to 12:00pm  ·  Space Science Seminar
Quintin Schiller, GSFC

Abstract: Within minutes of impacting Earth’s magnetosphere, interplanetary (IP) shocks can induce sudden and dramatic increases of relativistic electron flux.  The increases are understood to be caused by drift-resonance with the inward propagating magnetosonic pulse generated by the sudden compression of the dayside magnetosphere.  This physical process is capable of injecting electrons with energies >50 MeV to L<2.5, as observed during the March 24 1991 event.  Interestingly, the interplanetary shocks can simultaneously produce a relativistic electron flux depletio

Wednesday, November 1, 2017 - 3:00pm to 4:00pm  ·  Space Science Seminar
Yi-Hsin Liu, Dartmouth College

Abstract:  Earth's magnetosphere shields Earth against the constant bombardment of supersonic solar winds. However, the surface of this magnetic shield, called the magnetopause, can be eroded through various plasma mechanisms. Among them, magnetic reconnection is arguably the most important process. Reconnection not only allows the transport of solar wind plasmas into Earth magnetosphere but also enhances the convection of magnetic flux to Earth's night side.

Wednesday, October 18, 2017 - 3:00pm to 4:00pm  ·  Space Science Seminar
Caitano L. da Silva, Ph.D., Dartmouth College

Abstract:  Mechanisms of relativistic electron acceleration in plasmas are a subject of intense investigation. Some interesting examples are: unsteady magnetic reconnection in the solar wind leading to betatron and Fermi acceleration, runaway electron beam instabilities in tokamaks, and relativistic acceleration in the wakefields of high-power lasers. This talk briefly describes two research projects at Dartmouth aimed at understanding electron acceleration in atmospheric and space plasmas.