Bulletin of the American Physical Society
2021 Joint Spring Meeting of the Texas Sections of APS, AAPT and Zone 13 of the SPS
Volume 66, Number 2
Thursday–Sunday, April 8–11, 2021; Virtual
Session C10: APS: Astrophysics and Space Science-II |
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Saturday, April 10, 2021 11:00AM - 11:12AM |
C10.00001: Search for Transiting Exoplanets at Austin College's Adams Observatory in Support of NASA's TESS Mission Tanner O'Dwyer, Chloe Schnaible, Brett Skinner, David Baker NASA's Transiting Exoplanet Survey Satellite (TESS) utilizes the transit method to detect exoplanet candidates.~ As an exoplanet passes between its star and the telescope, the exoplanet blocks a small amount of light from the star. This reduction of light is recorded as a ``dip'' in the star's light curve. ~Due to the TESS space telescope's wide field of view and large pixel size, high precision ground-based observations through the TESS Follow-up Observing Program (TFOP) are needed to confirm planetary transits and eliminate false positives.~ The Adams Observatory at Austin College is a contributing member of TFOP.~~ During summer 2020, we observed and analyzed 11 stars identified by the TESS team as possible exoplanets.~ Our procedure used the software package AstroImageJ to calibrate images, conduct differential photometry, and generate light curves. Of our 11 observations, four observations showed an event detected on the target star, and these targets have been elevated to Verified Planetary Candidate (VPC) status. VPC's will be given priority for additional observations by other exoplanet detection methods. One Adams Observatory observation revealed a flat light curve on the target star but a deep transit on a nearby star, indicating a Nearby Eclipsing Binary (NEB). The other six observations showed flat curves on the target and nearby stars, which may indicate inaccurate ephemeris timing, a planet (and dip in the light curve) too small to detect, or a false positive.~ [Preview Abstract] |
Saturday, April 10, 2021 11:12AM - 11:24AM |
C10.00002: Dynamics of the Milky Way satellite galaxies with Gaia EDR3 Alex Riley, Louis Strigari The release of high-quality astrometric data from the Gaia space mission has revolutionized studies of the Milky Way's satellite galaxies over the past few years. Here, we combine measurements of satellite proper motions based on the latest Gaia data with literature distance and line-of-sight velocity measurements to study the dynamics of this system. We also present comparisons with cosmological simulations that track galaxy formation and evolution. The Milky Way satellites preferentially lie on tangential orbits, a kinematic signature consistent with a central galaxy disrupting orbits that pass nearby. The orbital poles of these satellites are also highly clustered, indicating the presence of a thin, rotationally-stabilized plane of satellites. These inferences are largely robust to the presence of the massive LMC on its first infall. [Preview Abstract] |
Saturday, April 10, 2021 11:24AM - 11:36AM |
C10.00003: Quantum Isotropy and the Reduction of Dynamics in Bianchi I Matthew Hogan We previously introduced a diffeomorphism-invariant definition of a homogeneous and isotropic sector of loop quantum gravity, along with a program to embed loop quantum cosmology into it. The present work works out that program in detail for the simpler, but still physically non-trivial, case where the target of the embedding is the homogeneous, but not isotropic, Bianchi I model. The diffeomorphism-invariant conditions imposing homogeneity and isotropy in the full theory reduce to conditions imposing isotropy on an already homogeneous Bianchi I spacetime. The reduced conditions are invariant under the residual diffeomorphisms still allowed after gauge fixing the Bianchi I model. We show that there is a unique embedding of the quantum isotropic model into the homogeneous quantum Bianchi I model that (a) is covariant with respect to the actions of such residual diffeomorphisms, and (b) intertwines both the (signed) volume operator and at least one directional Hubble rate. That embedding also intertwines all other operators of interest in the respective loop quantum cosmological models, including their Hamiltonian constraints. It thus establishes a precise equivalence between dynamics in the isotropic sector of the Bianchi I model and the quantized isotropic model. [Preview Abstract] |
Saturday, April 10, 2021 11:36AM - 11:48AM |
C10.00004: The ratio of the speed of light to the angular velocity of the rotation of an object is a measure of matter and dark matter Han yong quan Any specific object is self-rotating and also radiating. The radiation radius of the object: c/$\omega $, where c is the speed of light and $\omega $ is the angular velocity of the object's rotation. Assuming that the radius of an object is R, when R $=$ c/$\omega $, the object is in the critical state of matter and dark matter; when R\textless c/$\omega $, the object assumes the state of matter; when R\textgreater c/$\omega $, the object assumes the state of dark matter. At this time, the radiation of the object converges inside the object. The linear velocity of the object's rotation should be faster than the speed of light, and it is the existence form of dark matter, but they have gravitational effect, which is the characteristic of modern scientists describing dark matter. [Preview Abstract] |
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