Physics

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The Physics department is committed to education and research in physics, the study of the fundamental universal laws that govern the behavior of matter and energy, and the exploration of the consequences and applications of those laws. Our department is widely known for its excellent teaching and student mentoring. Our department plays an important role in the university’s Core Curriculum. We have strong academic programs with several options for undergraduate physics majors, leading to the B.S. degree, as well as graduate curricula leading to the M.S. and Ph.D. degrees. Our research groups span a variety of fields within physics. Our principal concentrations are in Astrophysics, Relativity, Gravitation and Cosmology, Condensed Matter Physics, Lasers and Optics, Physics Education, Solar Physics, and the Space Science and Engineering Lab.

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Author: search.filters.author.Qiu, JiongStart date: 2020

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Now showing 1 - 3 of 3
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    Tracing field lines that are reconnecting, or expanding, or both
    (Frontiers Media SA, 2024-07) Qiu, Jiong
    The explosive release of energy in the solar atmosphere is driven magnetically, but the mechanisms that trigger the onset of the eruption remain controversial. In the case of flares and coronal mass ejections (CMEs), ideal or non-ideal instabilities usually occur in the corona, but it is difficult to obtain direct observations and diagnostics there. To overcome this difficulty, we analyze observational signatures in the upper chromosphere or transition region, particularly brightening and dimming at the base of coronal magnetic structures. In this paper, we examine the time evolution of spatially resolved light curves in two eruptive flares and identify a variety of tempo-spatial sequences of brightening and dimming, such as dimming followed by brightening and dimming preceded by brightening. These brightening–dimming sequences are indicative of the configuration of energy release in the form of plasma heating or bulk motion. We demonstrate the potential of using these analyses to diagnose the properties of magnetic reconnection and plasma expansion in the corona during the early stages of the eruption.
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    Tracing field lines that are reconnecting, or expanding, or both
    (Frontiers Media SA, 2024-07) Qiu, Jiong
    The explosive release of energy in the solar atmosphere is driven magnetically, but the mechanisms that trigger the onset of the eruption remain controversial. In the case of flares and coronal mass ejections (CMEs), ideal or non-ideal instabilities usually occur in the corona, but it is difficult to obtain direct observations and diagnostics there. To overcome this difficulty, we analyze observational signatures in the upper chromosphere or transition region, particularly brightening and dimming at the base of coronal magnetic structures. In this paper, we examine the time evolution of spatially resolved light curves in two eruptive flares and identify a variety of tempo-spatial sequences of brightening and dimming, such as dimming followed by brightening and dimming preceded by brightening. These brightening–dimming sequences are indicative of the configuration of energy release in the form of plasma heating or bulk motion. We demonstrate the potential of using these analyses to diagnose the properties of magnetic reconnection and plasma expansion in the corona during the early stages of the eruption.
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    Structure of the Plasma near the Heliospheric Current Sheet as Seen by WISPR/Parker Solar Probe from inside the Streamer Belt
    (IOP Publising, 2023-05) Liewer, Paulett C.; Vourlidas, Angelos; Stenborg, Guillermo; Howard, Russell A.; Qiu, Jiong; Penteado, Paulo; Panasenco, Olga; Braga, Carlos R.
    Parker Solar Probe (PSP) crossed the heliospheric current sheet (HCS) near the perihelion on encounters E8 and E11, enabling the Wide-field Imager for Solar Probe (WISPR) to image the streamer belt plasma in high resolution while flying through it. With perihelia of 16 R⊙ and 13 R⊙ for E8 and E11, respectively, WISPR images enable investigation of the structure of density encasing the HCS at much higher resolution than reported previously. As PSP flies closer to the Sun, fine-scale structures are resolved within the coronal rays of the streamer belt. Near the HCS, WISPR observes a fan of rays of various sizes and brightnesses, indicating large density variations in the HCS plasma sheet transverse to the radial direction. Near the perihelion, when PSP's speed exceeds the solar corotation speed, some rays exhibit large changes in apparent latitude as the HCS is encountered, and rays pass over and under the spacecraft. The multiple viewpoints provided during the HCS crossing enable us to extract the coordinates of a few rays in a heliocentric frame. The rays were found to lie near the HCS from a PFSS model. We compare their locations to the location of the streamers as seen in synoptic maps from the Large Angle and Spectrometric Coronagraph, and find that the rays generally fall within the bright streamer bands seen in these maps, which confirms that they are features of the streamer belt plasma. We speculate that the density variations in the helmet streamer plasma result from continuous interchange reconnection along the coronal hole boundaries.
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