Physics

Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/52

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.

Browse

Filters

20242

Settings

Author: search.filters.author.Nidever, David L.search.filters.applied.f.department: search.filters.department.Physics

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Discovery of a split stellar stream in the periphery of the Small Magellanic Cloud
    (Oxford University Press, 2024-07) Nidever, David L.
    I report the discovery of a stellar stream (Sutlej) using Gaia DR3 (third data release) proper motions and XP metallicities located ∼15◦ north of the Small Magellanic Cloud (SMC). The stream is composed of two parallel linear components (‘branches’) approximately ∼8◦ × 0.6◦ in size and separated by 2.5◦. The stars have a mean proper motion of (μRA , μDec. ) = (+0.08 mas yr−1 , −1.41 mas yr−1 ), which is quite similar to the proper motion of stars on the western side of the SMC. The colour–magnitude diagram of the stream stars has a clear red giant branch, horizontal branch, and main-sequence turn-off that are well matched by a PARSEC isochrone of 10 Gyr, [Fe/H] = −1.8 at 32 kpc, and a total stellar mass of ∼33 000 M . The stream is spread out over an area of 9.6 deg2 and has a surface brightness of 32.5 mag arcsec−2 . The metallicity of the stream stars from Gaia XP spectra extends over −2.5≤ [M/H] ≤−1.0 with a median of [M/H] = −1.8. The tangential velocity of the stream stars is 214 km s−1 compared to the values of 448 km s−1 for the Large Magellanic Cloud and 428 km s−1 for the SMC. While the radial velocity of the stream is not yet known, a comparison of the space velocities using a range of assumed radial velocities shows that the stream is unlikely to be associated with the Magellanic Clouds. The tangential velocity vector is misaligned with the stream by nearly 90◦, which might indicate an important gravitational influence from the nearby Magellanic Clouds.
  • Thumbnail Image
    Item
    Unveiling the purely young star formation history of the SMC’s northeastern shell from colour–magnitude diagram fitting
    (Oxford University Press, 2024-07) Sakowska, J.D.; Noël, Noëlia E. D.; Ruiz-Lara, T.; Gallart, Carme; Massana, Pol; Nidever, David L.; Cassisi, Santi; Correa-Amaro, Patricio; Choi, Yumi; Besla, Gurtina; Erkal, Denis; Martínez‐Delgado, David; Monelli, M.; Olsen, Knut; Stringfellow, Guy S.
    We obtain a quantitative star formation history (SFH) of a shell-like structure (‘shell’) located in the northeastern part of the Small Magellanic Cloud (SMC). We use the Survey of the MAgellanic Stellar History to derive colour–magnitude diagrams (CMDs), reaching below the oldest main-sequence turnoff, from which we compute the SFHs with CMD-fitting techniques. We present, for the first time, a novel technique that uses red clump (RC) stars from the CMDs to assess and account for the SMC’s line-of-sight depth effect present during the SFH derivation. We find that accounting for this effect recovers a more accurate SFH. We quantify an 7 kpc line-of-sight depth present in the CMDs, in good agreement with depth estimates from RC stars in the northeastern SMC. By isolating the stellar content of the northeastern shell and incorporating the line-of-sight depth into our calculations, we obtain an unprecedentedly detailed SFH. We find that the northeastern shell is primarily composed of stars younger than 500 Myr, with significant star formation enhancements around 250 and 450 Myr. These young stars are the main contributors to the shell’s structure. We show synchronicity between the northeastern shell’s SFH with the Large Magellanic Cloud’s (LMC) northern arm, which we attribute to the interaction history of the SMC with the LMC and the Milky Way (MW) over the past 500 Myr. Our results highlight the complex interplay of ram pressure stripping and the influence of the MW’s circumgalactic medium in shaping the SMC’s northeastern shell.
Copyright (c) 2002-2022, LYRASIS. All rights reserved.