Category: Seminars

Monday December 5, 2016 Seminar: The Role of Magnetic Fields in Star Formation – Zeeman Effect Observations and other Observables

December 1st, 2016 in Seminars

The Role of Magnetic Fields in Star Formation – Zeeman Effect Observations and other Observables

Tom Troland
University of Kentucky

Monday, December 5, 2016
3:00 pm – Refreshments, CAS 500
3:45 pm – Seminar, CAS 502

Abstract:

TBA

Thursday November 17, 2016 Seminar: Rolling the BARREL the wrong way: Using Radiation Belt missions to study Solar Phenomena

November 15th, 2016 in Seminars


Rolling the BARREL the wrong way: Using Radiation Belt missions to study Solar Phenomena

Sarah McGregor
Keene State College

Thursday, November 17, 2016
3:45 pm – Refreshments, CAS 500
4:00 pm – Seminar, CAS 502

Abstract:

BARREL (Balloon Array for Radiation belt Relativistic Electron Losses) is an array of balloons launched by Dartmouth to study the Earth’s Radiation Belts. Intended to look at atmospheric losses of precipitating electrons, BARREL flew an array of balloons in Antarctica during the winter of 2014. But Radiation Belt electrons aren’t the only source of high energy particles that BARREL could potentially observe. Floating at higher latitudes it is possible for BARREL to observe Solar Energetic Particles as they penetrate into the Earth’s magnetosphere. The signature of these particles would be different than those of the Radiation Belts, and would be ‘noise’ to those looking for Radiation Belt Losses. In order to investigate Radiation Belt Losses BARREL measures high energy X -rays emitted from the precipitating particles as they enter the atmosphere. But these precipitating particles aren’t the only source of hard X-rays. The Sun, in the form of Solar Flares, does as well. Although predominantly characterized by their soft X-rays as observed by the GOES spacecraft, Solar Flares emit hard X-rays as energized particles plummet into the chromosphere. In this talk I will update you on some of our efforts to use the unintentional solar noise in BARRELs data, both from Solar Energetic Particles and Flares, to investigate solar dynamics and motivate undergraduates students to do Space Physics Research.

Monday November 14, 2016 Seminar: Gravitational Wave Detection with Advanced LIGO

November 8th, 2016 in Seminars

Gravitational Wave Detection with Advanced LIGO

Matthew Evans
MIT

Monday, November 14, 2016
3:15 pm – Refreshments, CAS 500
3:30 pm – Seminar, CAS 502

Abstract:

The Laser Interferometer Gravitational-wave Observatory (LIGO)recently made the first direct detection of gravitational waves; minute distortions in space-time caused by cataclysmic events far away in the universe. I will talk about the sources of the signals we detected, the physics behind the detectors, and prospects for the future of this emerging field.

Thursday November 10, 2016 Seminar: Update from the MMS Mission

November 8th, 2016 in Seminars


Agyrotropy in the Electron Diffusion Region of Asymmetric Magnetic Reconnection

Matthew Argall
UNH

Thursday, November 10, 2016
3:00 pm – Seminar, CAS 500

Abstract:

The Magnetospheric Multiscale (MMS) mission was launched on March 13, 2015 and consists of four spacecraft in a tetrahedral configuration. Its mission is to unravel the mystery of particle acceleration in collisionless plasmas during magnetic reconnection. It has set a world record for use of GPS at the highest altitude of any space mission — a feat that has allowed it to maintain a mean seperation 7km or 2-3 electron skin depths at magnetopause. This formation has allowed MMS to spatially resolve electron-scale structures. Furthermore, the unprecedented time-resolution of the fields and particles suites has made it possible to study many of the rapidly changing processes of reconnection. Once such process is plasma mixing and acceleration in the electron diffusion region (EDR), which leads to agyrotropic electron distribution functions. In this seminar, I will present an overview of MMS, some of its recent discoveries, and the insight the Electron Driff Instrument (EDI) is providing in our study of the EDR.

Monday November 7, 2016 Seminar: Supernovae and their Progenitor Systems

November 8th, 2016 in Seminars

Supernovae and their Progenitor Systems (or lack thereof)

Ori Fox
STScl

Monday, November 7, 2016
3:15 pm – Refreshments, CAS 500
3:30 pm – Seminar, CAS 502

Abstract:

Despite the robust empirical supernova (SN) classification scheme in place, the underlying progenitor systems remain ambiguous for many subclasses. The most straightforward constraint relies on a detection of the progenitor star in high-resolution pre-explosion images. Such a direct identification is typically not feasible, however, even with modern telescopes such as Hubble. Instead, astronomers are forced to rely on supernova “forensics,” where the surrounding circumstellar medium can yield direct clues about the mass loss from the star in the years leading up to the SN explosion.
I will begin the talk with a review of the limited number of direct progenitor detections already made, followed by a discussion of the indirect methods for constraining supernova progenitors that have never been seen. Although pro- genitor discussions have historically considered mostly single star systems, I will focus a significant portion of the discussion on the impact binary stars may have on our understanding of these results.

Thursday November 3, 2016 Seminar: Human-in-the-Loop Coordination with Robot Systems

October 27th, 2016 in Seminars

Human-in-the-Loop Coordination with Robot Systems

Holly Yanco
U Mass Lowell

Thursday, November 3, 2016
3:00 pm – Refreshments, CAS 500
3:45 pm – Seminar, CAS 502

Abstract:

Robots navigating in difficult and dynamic environments often need assistance from human operators or supervisors, either in the form of teleoperation or interventions when the robot’s autonomy can not handle the current situation. Even in more controlled environments, such as office buildings and manufacturing floors, robots may need help from people. This talk will discuss the best practices for controlling both individual robots and groups of robots, in applications ranging from assistive technology to telepresence to search and rescue. A number of methods for human-in-the-loop coordination with robot systems, including multi-touch devices, software-based operator control units (softOCUs), game controllers, Oculus Rift, and Google Glass, will be presented.
Bio: Dr. Holly Yanco is a Distinguished University Professor, Professor of Computer Science, and Director of the New England Robotics Validation and Experimentation (NERVE) Center at the University of Massachusetts Lowell. Her research interests include human-robot interaction, multi-touch computing, interface design, robot autonomy, fostering trust of autonomous systems, evaluation methods for human-robot interaction, and the use of robots in K-12 education to broaden participation in computer science. Yanco’s research has been funded by NSF, including a CAREER Award, ARO, DARPA, DOE-EM, NASA, NIST, Microsoft, and Google. Yanco was the General Chair of the 2012 ACM/IEEE International Conference on Human-Robot Interaction and served as Co-Chair of the Steering Committee for the HRI Conference and Journal from 2013-2016. Yanco has a PhD in Computer Science from the Massachusetts Institute of Technology.

Monday October 31, 2016 Seminar: HETDEX and the Star-Forming Galaxies of the Z~2 Universe

October 27th, 2016 in Seminars

HETDEX and the Star-Forming Galaxies of the Z~2 Universe

Robin Ciardullo
Penn State

Monday, October 31, 2016
3:15 pm – Refreshments, CAS 500
3:30 pm – Seminar, CAS 502

Abstract:

In a few months, the Hobby Eberly Telescope Dark Energy Experiment will begin obtaining redshifts for roughly a million Ly-alpha emitting galaxies (LAEs) between
1.9 < z < 3.5. While the main purpose of the project is to study the evolution of Dark Energy, the project will produce an incredible data base for studies of galaxy evolution. In preparation for this, we have been investigating the physical and chemical properties of emission-line galaxies in the z ~ 2 universe, using LAEs discovered from the ground and samples of [O III]-emitting gal- axies identified from space. We show that LAEs are not “low mass, dust-poor galaxies caught in the act of formation”, but instead normal star-forming galaxies with stellar masses that span almost the entire galaxy mass range, from at least 7.5 < log M/Msun < 10.5. We use our z ~ 2 galaxy samples to explore issues such as the relationship between stellar mass and metallicity, the systematics of star-formation rate indicators, the behavior of dust attenuation laws versus stellar mass, and the question of what makes an LAE an LAE.

Thursday October 27, 2016 Seminar: The Shifting Paradigm of the Martian Magnetosphere: MAVEN Observations

October 25th, 2016 in Seminars

The Shifting Paradigm of the Martian Magnetosphere: MAVEN Observations

Gina A DiBraccio
USRA/NASA Goddard Space Flight Center

Thursday, October 27, 2016
3:00 pm – Refreshments, CAS 500
3:45 pm – Seminar, CAS 502

Abstract:

The Martian magnetosphere forms as the solar wind interacts with the planet’s upper atmosphere. This interaction is complicated by the presence of localized crustal magnetic fields, with the largest sources located in the southern hemisphere. We investigate the Martian magnetosphere by analyzing comprehensive particle and field data provided by NASA’s Mars Atmospheric Volatile EvolutioN (MAVEN) spacecraft, which went into orbit about Mars on 21 September 2014. The Martian space environment is typically categorized as an induced magnetosphere, similar to that of Venus; however, as MAVEN continues to collect valuable data, we identify characteristics in the Martian magnetosphere that are similar to intrinsic magnetospheres. Focusing on the magnetotail of Mars, we present evidence of these features including: 1) Magnetic reconnection in the cross-tail current sheet; 2) Flux rope formation; 3) Current sheet flapping; and 4) Evidence that the magnetotail is comprised of both draped interplanetary magnetic field and open planetary fields. These MAVEN observations confirm that the Martian magnetotail has a hybrid configuration between an intrinsic and induced magnetosphere, shifting the paradigm of Mars as we have understood it thus far.

Monday October 24, 2016 Seminar: Probing Black Hole Variability on Days Century Timescales

October 18th, 2016 in Seminars

Probing Black Hole Variability on Days Century Timescales

Josh Grindlay
CfA

Monday, October 24, 2016
3:00 pm – Refreshments, CAS 500
3:45 pm – Seminar, CAS 502

Abstract:

After a long recovery from a major flood on Jan. 18, on Aug. 4 our Digital Access to a Sky Century @ Harvard (DASCH) project had its 5th Data Release (DR5), making nearly full coverage of the Galactic latitude range b = 15 – 90deg (~37% of the sky) available for optical variability studies on days to century timescales. After a brief overview of DASCH and how it all works, I will describe one of the primary science goals for DASCH to measure historic outbursts of accreting black holes in low mass X- ray binaries (all are transient sources) to constrain their outburst recurrence
times and total numbers. Initial results suggest that the black hole LMXB population exceeds that for neutron star LMXBs, implying the BH-LMXBs can be more easily formed. I will outline a possible formation mechanism. Supermassive black holes in AGN, particularly Blazars, are another prime topic for DASCH. I will show results on several systems that reveal
both apparent QPOs (in 3C273) and extreme flares in several well known Blazars. I will also show two possible DASCH detections of periodicities in AGN that have been recently reported from modern data.

Thursday October 20, 2016 Seminar: Magnetic Reconnection: from the Sweet-Parker Model to the Stochastic Plasmoid Chains

October 13th, 2016 in Seminars

Magnetic Reconnection: from the Sweet-Parker Model to the Stochastic Plasmoid Chains

Nuno Loureiro
MIT

Thursday, October 20, 2016
3:30 pm – Refreshments, CAS 500
4:00 pm – Seminar, CAS 502

Abstract:

Magnetic reconnection is the topological reconfiguration of the magnetic field in a plasma, accompanied by the violent release of energy and particle acceleration. Reconnection is as ubiquitous as plasmas themselves, with solar flares perhaps the most popular example.
Over the last few years, the theoretical understanding of magnetic reconnection has undergone a major paradigm shift. The steady-state model of reconnection described by the famous Sweet-Parker theory, which dominated the field for ~50 years, has been replaced with an
essentially time-dependent, bursty picture of the reconnection layer, dominated by the continuous formation and ejection of multiple magnetic islands (plasmoids). This has led to a complete revision of the current understanding of reconnection and its observable signatures, with deep implications for astro, space and laboratory reconnection sites.
This talk aims to review the recent developments in reconnection that led to this essentially new framework, and discuss the outstanding challenges that remain at the frontier of this subject.