College of Arts and Sciences Speaker Series

Join us for the Science Speaker Series, hosted by the Physics, Biology and Chemistry departments on select Tuesdays and Thursdays at Noon in the Jim and Linda Lee Planetarium! This series features captivating talks from guest speakers outside ERAU, faculty experts within ERAU and student presentations (REUs or Capstone projects) in the College of Arts and Sciences.

For suggestions, comments or volunteering opportunities, contact Dr. Pragati Pradhan at pradhanp@erau.edu, Dr. Quentin G. Bailey at baileyq@erau.edu or Dr. Steve Waples at steve.waples@erau.edu.

Stay tuned for updates on this event page, or watch out for emails.

Next Event

When: April 16, 2026 at noon
Where: Jim and Linda Lee Planetarium

Title: Capstone student research talk

Speaker: Roberta Cooper
Title: Confirming the Periodic Disk Outbursts of the Be star HD 6226
Abstract: Classical Be stars are rapidly-rotating B stars that eject material into an equatorial gaseous disk. The disk is observed through optical spectroscopy, especially with hydrogen Balmer lines, infrared excesses from scattering, and where polarization and/or interferometry can resolve the orientation of the disk. The mechanisms that lead to disk ejection or dissipation are still unknown. In 2021, Richardson et al. reported on a periodic behavior for the Be star HD 6226 with ~four years of data, where a combination of two frequencies could predict the overall disk behavior. We used a larger data set spanning 20 years to measure the Hα and Hβ variability of HD 6226. We confirm the findings that the overall disk behavior is periodic, with slight modifications and improvements to the previously reported frequencies.

Speaker: Hailey Widger
Title: Broad-band X-ray spectral analysis of symbiotic X-ray binary GX 1+4 to disentangle the emission mechanism
Abstract: This project aims to advance the understanding of matter in extreme environments by analyzing the
first broadband monitoring of symbiotic X-ray binary GX 1+4 almost every month in 2024-2025 using near-simultaneous data from NICER and NuSTAR X-ray telescopes. The primary scientific objective is to investigate competing theories proposed in literature for the X-ray emission from GX 1+4 caused by (i) inverse Compton scattering in an accretion column (similar to many high mass X-ray binaries where the neutron star is endowed with a strong magnetic field) - with or without a wind-fed accretion disk. (ii) The other possibility is Compton reflection off a cold, optically thick structure, likely the inner region of an accretion disk or torus. We will also discuss the possibility of X-ray variability in GX 1+4 caused by quasi-spherical accretion. This abstract focuses on the X-ray spectral analysis of the source and is linked to another abstract (led by Maan Janbi) which discusses the timing properties of GX 1+4. Our work has broader implications concerning the mechanisms producing the X-ray emission from massive X-ray binaries and the properties of accreting-matter flows in these enigmatic objects.

Speaker: Maan Janbi
Title: Pulse profile dependence of GX 1+4 on energy and luminosity
Abstract: We present the first-ever systematic pulse profile monitoring of the symbiotic X-ray binary GX 1+4 with NuSTAR, conducted monthly throughout 2024–2025. Pulsations are detected in all observations and we could establish a steadily spin-down trend of the pulsar hosted in GX 1+4 across all NuSTAR data. The pulse profiles display a wide range of morphologies, including double- and triple-peaked structures, which are observed to vary with both energy and luminosity. In this work, we investigate the energy and luminosity dependence of the profiles, with a particular focus on understanding the origin and evolution of the dips unveiled across different pulse phases. This study provides new insights into the accretion geometry and emission mechanisms in GX 1+4.

Speaker: Guru Balakrishnan
Title: Understanding Orbital Variability of Cen X-3 using NICER1
Abstract: We present results from orbital monitoring of Cen X-3 with NICER over three consecutive orbits of the source. We find that each orbit exhibits a distinct orbital profile, though all are broadly consistent with the source being in its long-term moderate state. Through spectral analysis, we investigate if
the observed differences are likely due to variations in the accretion wake or partial occultation by the accretion disk. We fit the spectra with a blackbody plus a power-law and multiple emission lines to study variability across observations. We also examine pulse profiles to identify changes in the
physical conditions driving the X-ray variability of the source. The pulse profiles appear remarkably consistent across luminosity and energy, suggesting that the overall geometry of the accretion column and emission regions remains stable despite orbital variations.

Speaker: Jack Hedberg
Title: Gravitational Wave Signatures and Prospects for Detecting Quantum Gravity Effects
Abstract: This work explores the possibility of detecting quantum gravity effects indirectly through statistical fluctuations in graviton behavior, despite the impracticality of direct graviton detection. By applying tools such as the Palatini formulation, Quantum Fisher Information, and the Quantum Cramér–Rao Bound, the study evaluates whether such quantum signatures could be observable with detectors like LIGO.

Speaker: William Punches
Title: A First Orbit for the Binary Wolf Rayet LS III +44 21
Abstract: Wolf-Rayet (WR) stars are massive, hot stars typically nearing the ends of their lives. They are characterised by broad emission lines from powerful stellar winds. While numerous binary WR systems are known, very few are eclipsing and even fewer are core-eclipsing. LSIII +44 21 provides a rare opportunity to analyze such a core-eclipsing WR and O-star system. The 4.43 day orbit of the system provides regular eclipses, allowing improved modelling of the orbital geometry. We present a first orbit for this system using high-resolution TESS photometry as well as Gemini-N and MAROON-X spectroscopy. Extracted radial velocities for the WR star show a phase offset from the O-star velocities. This indicates strongly interacting stellar winds and the presence of a shock-front between them.

Speaker: Dante Colecchia
Title: The Variability of Be Stars in the Pleiades As Observed By TESS
Abstract: Be stars are rapidly rotating B class stars that show emission lines primarily in the Balmer series. This is due to the presence of a disk at the star’s equator that forms through the loss of ejected stellar mass.These emission lines come and go as the disk forms and gets blown away by stellar wind. As for the Pleiades, observations by TESS show periodic changes in flux for Pleione, Merope, Electra, and Alcyone. The aim of this paper is to denoise the observed light curves for each star and find the correlation between flux and changes in pulsation of the disks.

Speaker: Joseph Ribaudo
Title: An Exploration of Bipartite Gravitational-Wave Detection
Abstract: Current research into the quantization of gravity has focused primarily on single-point graviton detections. This approach neglects non-classical properties that arise from entanglement between gravitons whose arrivals are coincident at separate detector sites. In developing a bipartite quantum-mechanical framework for the detection of gravitational waves, a necessary step is to characterize detector efficiency for graviton particles. We find that low detector efficiency results in resolvable measurement-induced entanglement in bipartite gravitational-wave detections.

Upcoming talks

April 17, 21 : Capstone student talks