Throughout the Fall Semester Space Science and CSPAR will be conducting a Colloquium. We invite both faculty and students to join us! Refreshments for the audience are served after the talk. Check for dates, speakers, and topics below. For further information on the Colloquium, please contact space_science_colloquium@uah.edu.

Important

Covid must be test negative. Masks are required for in-person Colloquium. In-person Colloquium will be held Fridays at 12:30pm in Cramer Hall (CRH), room 2096 and on dates provided for each speaking engagement. View Campus Map.

Parking: Visitors need to sign in at the Cramer Hall front desk and have their ID in order to get a parking pass. View Campus Map.


Date: 9/23/22
Speaker: Gang Li, Professor, UAH
Type:
in-person, talk
Title:Configuration of solar wind magnetic field and energetic electrons in the inner heliosphere

Abstract:

In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares, electrons can be accelerated to multi-MeV and ions to several hundred MeV/nuc, causing the observed hard X-rays and gamma rays.  These events are often classified as impulsive events. While the underlying acceleration mechanisms in these events is still under debate,  in-situ energetic electrons in these events have offered a practical tool in understanding the solar wind magnetic field configuration. On some occasions, it also provides stringent constraints on the underlying acceleration mechanisms.  In this talk, I will discuss a recently developed data analysis method, called the Fractional Velocity Dispersion Analysis (FVDA).  Employing the FVDA, I show how one can use in-situ energetic electron observations to obtain the release times of these electrons at the flare site, as well as the corresponding turbulence spectrum index. Furthermore, using FVDA one can also examine the solar wind magnetic field configurations.  Examples of electron reflection beyond 1 AU will be shown, illustrating the large variety of the IMF.

 


Date: 10/14/22
Speaker: Haimin Wang Distinguished Professor of Physics, NJIT
Type: in-person, talk, (may change subject to covid)
Title: "Study Solar Activity with High Resolution Observations and Machine Learning"

I will first summarize some discoveries using the 1.6m Goode Solar Telescope

(GST) at Big Bear Solar Observatory (BBSO) and explain why GST and newly

built 4-m Danial K. Inouye Solar Telescope (DKIST) are complementary in

research. I will the summarize some of scientific results: (1) The small scale

magnetic structure evolution leading to solar eruptions. (2) With highest resolution observations, the photospheric magnetic structure changes can be tracked from flaring polarity inversion lines (PIL) propagating outwards. These include the sudden flare-induced rotation of sunspots and the increase of transverse magnetic fields near PIL. This provides some clear clues to the so-called “Dog vs. Tail” problem. (3) We recently found extremely strong (>5500G) fields in PIL of flaring

sunspot in the famous solar active region of September 2017. (4) Flares ribbons may show absorptions instead of emissions. Modeling can explain those negative flares. Finally, I will introduce applications of machine learning and artificial intelligence in processing the “Big Data” from our observations. These examples will include automatic feature recognition and tracking, as well as the forecasting of solar eruptions. In particular, I will introduce a ML tool to generate vector magnetograms from line-of-sight magnetograms and Halpha images, extending synoptic vector magnetograms to SOHO/MDI era, as well improving spatial resolution for HMI data using GST data as a training set.


Date: 10/21/22
Speaker: Gary Zank, Distinguished Professor, UAH
Type: in-person, talk, (may change subject to covid)
Title:On Magnetohydrodynamics, Fluctuations, Structures, and Turbulence"


Special Colloquium

Date: 10/26/22, room 2096, 4pm-5pm
Speaker: Shuichi Matsukiyo, ESST Kyushu University, Japan
Type: in-person
Title: “Test particle simulation of cosmic ray invasion into the heliosphere"


Date: 11/11/22
Speaker: Daniele Telloni, Researcher | National Institute for Astrophysics Astrophysical Observatory of Torino, Italy
Type: virtual
Title:Multi-spacecraft and multi-instrument study of the solar wind in the corona and heliosphere

Abstract: The evolution of waves and turbulence in the expanding solar wind is mostly studied statistically using broad ensembles of measurements taken at different times, at different heliocentric distances, and under different solar wind and solar conditions. Standard techniques, including power spectra and structure functions, multifractal analysis, third-order scaling laws and energy transfer, Alfvénicity, wave coherence, structure identification, non-Maxwellian features of particle distribution functions, are normally used to describe the properties of the fluctuations and how they heat and energize the plasma. However, due to the intrinsic variability and inhomogeneity of the solar wind and of its solar sources, this approach cannot capture the fundamental dynamical evolution of turbulence and the related plasma heating, necessary for understanding the general physical processes and correctly modeling the heliosphere. Using specific configurations to obtain rare measurements of the same plasma parcel by two radially aligned spacecraft may allow understanding the actual evolution of waves, turbulence and heating under different conditions. Additionally, compared observation of the solar/coronal sources and in-situ properties, possible during quadratures, will help

address the origin of turbulence and its dependency on the solar structure. As a matter of fact, linking plasma kinetic properties (waves, instabilities, energy deposition) with large-scale coronal structures will represent a breakthrough to the long-standing problem of coronal heating, onset of plasma instabilities, and wave generation. This talk reviews the most recent results obtained by exploiting the joint in-situ and remote-sensing observations during the first Parker Solar Probe - Solar Orbiter radial alignments and quadratures, and in particular the radial evolution of solar wind turbulence and solar-wind connectivity with coronal sources.


Date: 11/18/22
Speaker: P. H. Diamond, Distinguished Professor of Physics, UCSD
Type: in-person, talk
Title:Mixing vs Anti-Diffusion-The Competition in Elastic Turbulence