Bulletin of the American Physical Society
2016 Annual Meeting of the APS Mid-Atlantic Section
Volume 61, Number 16
Saturday–Sunday, October 15–16, 2016; Newark, Delaware
Session G1: Astronomy, Astrophysics and High Energy Physics II |
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Chair: John Gizis, University of Delaware Room: Sharp Laboratory 123 |
Sunday, October 16, 2016 1:30PM - 2:06PM |
G1.00001: Convection in Cool Stars, as Revealed through Stellar Brightness Variations Invited Speaker: Fabienne Bastien As a result of the high precision and cadence of space-based photometric surveys like Kepler, we may now directly observe the very low-level light variations arising from stellar granulation in cool stars. Here, we discuss how this enables us to more accurately determine the physical properties of Sun-like stars, to understand the nature of surface convection and its connection to magnetic activity. We present recent results that tie "flicker" to granulation and enable a simple measurement of stellar surface gravity with a precision of ~0.1 dex. We discuss how these light curves can be used to probe stellar evolution and help place constraints on models of stellar convection. We show that flicker may be used to probe convection in stars with surface gravities as low as 1.5, and we demonstrate that, in concert with asteroseismically measured surface gravities, it might be used to examine differences in the convective properties of red giant, red clump, and secondary clump stars. Finally, we discuss how we may quantitatively predict a star's radial velocity jitter from its brightness variations, permitting the use of discovery light curves to help prioritize follow-up observations of transiting exoplanets and to open exoplanet discovery in previously inaccessible domains. [Preview Abstract] |
Sunday, October 16, 2016 2:06PM - 2:18PM |
G1.00002: Measurement of the low energy cosmic ray spectrum with IceTop-81 Ramesh Koirala, Thomas Gaisser IceTop, the surface component of the IceCube Neutrino Observatory which consists of 81 stations and two ice Cherenkov tanks at each station, can measure the cosmic ray energy spectrum. The cosmic ray energy spectrum is a key observable to study cosmic ray production and mass composition. The IceTop spectrum thus far covers only an energy region from 2 PeV to 1 EeV. The goal is to lower the energy threshold to make contact with direct measurements of the primary spectrum made with detectors on balloons. The standard IceTop reconstruction requires a minimum of five stations. To lower the energy threshold, we have to use the more closely spaced inner stations and require only two of those stations to be hit. So we developed and deployed a new trigger that can select events with two or more stations hit. Here we will discuss the new IceTop trigger and an ongoing effort to lower the energy threshold, possibly to 100 TeV. We will also discuss measures to implement the measured spectrum to possibly get mass composition. [Preview Abstract] |
Sunday, October 16, 2016 2:18PM - 2:30PM |
G1.00003: A New Method for Finding Point Sources in High-Energy Neutrino Data Mark Giovinazzi, Ke Fang, Coleman Miller The IceCube Neutrino Observatory has not yet been able to identify an astrophysical point source from which a high-energy neutrino has originated. In this analysis, we implement a new method for finding such point sources by choosing to examine pairs of detected events rather than individual ones, noting that clusters of events are more likely to come from a single source than those from widely different parts of the sky. We wish to measure the angular distances between all possible pairs of events, scaling each by the pair's angular resolution errors summed in quadrature. Furthermore, we compare this result to statistically generated distributions of both a diffuse and a clustered set of events. Our new method is thus designed to teach us exactly how point-source-like our sample of detected events really is. We propose that our analysis should be able to determine the origins of any given clustering of events within the IceCube data, allowing us to discover the first neutrino point source in history. [Preview Abstract] |
Sunday, October 16, 2016 2:30PM - 3:06PM |
G1.00004: IceCube and High Energy Neutrino Astronomy Invited Speaker: Naoko Kurahashi Neilson The Universe has been studied using light since the dawn of astronomy, when starlight captured the human eye. The IceCube Neutrino Observatory sees the Universe in a new way, using high-energy neutrinos as the messenger. In 2013, a diffuse emission of neutrinos from the cosmos was discovered by IceCube. Now the hunt is on to identify the sources of such astrophysical neutrinos. After discussing the state of neutrino astronomy, plans for a streamlined real-time alert system for multi-messenger observations, and future plans of new detectors at the South Pole will also be presented. [Preview Abstract] |
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