Fall 2024 Colloquium

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 before the talk. Check for dates, speakers, and topics below. For further information on the Colloquium, please contact space_science_colloquium@uah.edu.

Date & Place: 9/27/2024, Room 1010
Speaker: Dr. Michael Briggs, Research Scientist VI, CSPAR, UAH
Title: The StarBurst Multimessenger Pioneer

Abstract:

The StarBurst Multimessenger Pioneer is a highly sensitive and wide field gamma-ray monitor designed to detect the prompt emission of short gamma-ray bursts (SGRBs), a key electromagnetic (EM) signature of neutron star (NS) mergers. In conjunction with gravitational wave (GW) and follow-up observations across the EM spectrum, StarBurst seeks to understand neutron star mergers through multimessenger observations and address four primary science objectives: 1) Constrain the progenitors of SGRBs, 2) Probe the remnants of NS mergers, 3) Constrain the neutron star equation of state, and 4) Probe the structure of relativistic outflows produced in neutron star mergers.

StarBurst is designed to capitalize on the new era of multimessenger astronomy by utilizing the advancements in gamma-ray detectors made over the last decade. With over five times the effective area of the Fermi Gamma-ray Burst Monitor (GBM) and full coverage of the unocculted sky (8 Sr), StarBurst will make highly sensitive observations of EM counterparts to NS mergers and be a key partner to the GW network in observing NS mergers at a fraction of the cost of currently operating gamma-ray missions. Starburst is led by MSFC with contributions from UAH, USRA and NRL.

The StarBurst Pioneer has high heritage from previous NASA gamma-ray instruments, Fermi GBM, SIRI, BurstCube, and Glowbug, leading to reduced cost and development risk. Starburst will fly an array of 12 CsI(TI) scintillator detectors that utilize new, low mass and low voltage, Silicon photomultipliers (SiPM) to cover an energy range from 30 keV to 2 MeV. The detector design and readouts are based on the NRL Glowbug instrument.  The ground analysis software has high heritage from Fermi GBM and BurstCube.  UAH is contributing development of the instrument flight software, which is based on the flight softwares of GBM and BurstCube.   The UAH team will also use its experience in gamma-ray detectors to lead the calibration of the StarBurst instrument.

Date & Place: 10/18/2024, Room 2096
Speaker: Dr. Laxman Adhikari, Assistant Professor, Space Science/CSPAR, UAH
Title: PUI driven turbulence in the upwind and downwind directions in the outer heliosphere

Abstract:

Interstellar neutral hydrogen (ISN H) is the main source of pickup ions in the outer heliosphere. ISN H easily penetrates the heliopause, enters the heliosphere, crosses the heliospheric termination shock (HTS), and interacts with the solar wind. ISN H follows a trajectory influenced by both gravitational attraction and solar radiation pressure until it is ionized by the solar wind or energetic solar photons. After the ionization of ISN H, an H+ ion is formed. The newly born H+ ions are accelerated immediately by the motional solar wind electric field, forming pickup ions (PUIs) that stream along the magnetic field to form a ring-beam distribution. The ring-beam distribution is unstable and drives various plasma instabilities, resulting in the generation of MHD waves and driving turbulence in the outer heliosphere. The distribution of ISN H in the upwind direction is larger than that in the downwind direction, which results in the upwind PUI source being stronger than the downwind PUI source.

This results in different turbulence properties in the two directions. We develop a four-fluid solar wind model by coupling the four-fluid (proton, electron, pickup ion, and interstellar neutral hydrogen) solar wind equations with the high-β regime nearly incompressible magnetohydrodynamic (NI MHD) turbulence model equations. The advantage of the fluid model is that we do not need to use an empirical expression for the interstellar neutral hydrogen density, which is also used in the pickup ion source of turbulence. In our model, the production of pickup ions is proportional to the ISN H density and directly affects the solar wind speed. We validate the model results against the New Horizons SWAP (upwind direction), and the Pioneer 10 (downwind direction) measurements. In this talk, I will discuss the physical processes in the PUI-mediated solar wind in the outer heliosphere: the radial evolution of the i) PUI density, PUI pressure, and PUI temperature; ii) ISN H density, ISN H speed, and ISN H temperature; iii) solar wind density, solar wind speed, and solar wind temperature; iv) solar wind density fluctuations, and v) the turbulence energy and the corresponding correlation lengths. This talk will discuss how the PUI and/or ISN H influence the solar wind plasma/solar wind turbulence in the outer heliosphere.

Date & Place: 10/25/2023, Room 1010
Speaker: Dr. Alphonse  Sterling, Astrophysicist NASA/MSFC
Title: Solar Coronal Jets, and Implications for Solar Eruptions on Larger and Smaller Size Scales

Abstract:

Large-scale solar eruptions often include ejection of a filament, a solar flare, and expulsion of a coronal mass ejection (CME). Unravelling the magnetic processes that build up the free energy for these eruptions and trigger that energy's release in the eruption is a continuing challenge in solar physics. Such large-scale eruptions are comparatively infrequent, with the moderate level ones (say, GOES M-class events) occurring perhaps once every few days on average during active-activity times, and much less frequently during quieter times. In contrast, solar coronal jets, which are long (~50,000 km), narrow (<~10,000 km), transient (~10---20 min) plasma spires with bright bases and that are seen in soft X-rays and EUV, occur much more frequently, likely several hundred times per day independent of large-scale solar activity level. Recent studies indicate that coronal jets are small-scale versions of large-scale eruptions, often produced by eruption of a small-scale "miniflament," that results in a "miniflare" analogous to a larger typical solar flare, and that sometimes produces a CME analogue (a "narrow CME" or "white-light jet"). Because of this, we can study the more-more-frequent coronal jets to learn about the comparatively infrequent larger-scale eruptions. Moreover, jet-like eruptions apparently occur on size scales much smaller than coronal jets, and such small-scale jetting is a candidate for powering the solar wind and perhaps generating fluctuations in the solar wind known as "switchbacks." This work was supported by NASA's Heliophysics Supporting Research (HSR) and Heliophysics System Observatory Connect (HSOC) Programs, and by the NASA/MSFC Hinode Project.

Date & Place: 11/15/2024, Room 2096
Speaker: Subramania Athiray Panchapakesan, Assistant Professor, UAH
Title: Slitless spectroscopy for solar corona - A new paradigm from MaGIXS

Abstract:

Imaging of the Sun at high energies in EUV and X-rays have revolutionized our understanding of the outermost atmosphere of the Sun, the solar corona. Precise determination of plasma diagnostics including temperature, density, abundances, line-of-sight velocities require spectroscopy. Traditionally, slit-based instruments probe the Sun with high spectral resolution through long, narrow slits. 2D pure spectral images are created by stepping the slit, called raster, over the region of interest. During the raster process, we lose co-temporal observations of the spatial structures. This difficulty can be overcome with slitless spectrograph instruments, which can take a snapshot of a wide field of view on the Sun, with dispersed spectral images overlapped from different spatial locations on the Sun. Such instrument was last flown successfully in Skylab and were abandoned since 1970s due to the difficulty of unfolding the overlapping spatial and spectral information. Such data are called spectroheliogram (or) overlappogram. Recently, novel inversion algorithms have been successfully demonstrated to unlock the potential of slitless spectrographs. The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS), a NASA sounding rocket mission, pioneered measurement of the soft X-ray overlappogram of the solar corona. The first flight MaGIXS-1 was launched successfully in 2021 and observed several diagnostic emission lines to constrain frequency of heating in X-ray bright points. Most recently the second successful flight MaGIXS-2 was launched on 16 July 2024 and observed 4 active regions with different stages of evolution. Here, I will present an overview of overlappogram instruments, showcase science highlights from MaGIXS-1 flight and exciting progress from MaGIXS-2. At the end I will also mention the plans for MaGIXS-3 and discuss how MaGIXS paves a way for next generation space instrumentation.

Date & Place: 11/22/2024, Room 1010
Speaker: Dr. Parisa S. Mostafavi, Applied Physics Lab, Johns Hopkins University
Title: Cancelled

Abstract:

Cancelled

Spring 2024 colloquium schedule 

Fall 2023 colloquium schedule 

Spring 2023 colloquium schedule

 Fall 2022 colloquium schedule