Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session JJ01: V: Small: Stars, Planets, & Space Science |
Hide Abstracts |
Sponsoring Units: DAP Chair: Saravana Prakash Thirumuruganandham, Centro de Investigación de Ciencias Humanas y de la Educació Room: Virtual Room 1 |
Monday, April 24, 2023 6:00PM - 6:12PM |
JJ01.00001: Rapidly Rotating Massive Pop III stars: A Solution for High Carbon Enrichment in the Early Galaxy Jeena S K, Projjwal Banerjee, Alexander Heger Very metal-poor (VMP) stars ([Fe/H]$< -2$) of mass $lesssim 0.8, M_odot$ are thought to be the fossil records of the nucleosynthesis of the earliest generation of massive stars that were present in the early Galaxy. A large fraction of VMP stars are found to be enhanced in C relative to Fe ([C/Fe]$>0.7$) and are referred to as carbon-enhanced metal-poor (CEMP) stars. A subclass of CEMP stars with a low enrichment of heavy elements are called CEMP-no stars and are thought to have formed from the interstellar medium (ISM) polluted by the supernova ejecta of the very first generation (Pop III) massive stars. Although theoretical models of supernova explosions can explain the relative abundance pattern reasonably well, the very high enrichment of C ([C/H]$gtrsim -2.5 $) observed in many of the CEMP-no stars is difficult to explain when reasonable values of dilution of the supernova ejecta with the ISM are adopted. We explore rapidly rotating models of Pop III stars that undergo efficient mixing and reach the so-called quasi-chemically homogeneous (QCH) state. We find that rapidly rotating models that reach the QCH state can eject substantial amounts of C in the wind. The resulting dilution of the wind ejecta in the ISM can naturally explain the high C enrichment observed in CEMP-no stars. We find that rapidly rotating massive Pop III stars are a promising site for explaining the origin of CEMP-no stars. This also suggests that a significant number of Pop III stars were rapid rotators. |
Monday, April 24, 2023 6:12PM - 6:24PM |
JJ01.00002: Illuminating the Pair-Instability supernova mass gap with multi-messenger signals Aman Agarwal, Daniel Siegel, Brian Metzger, Jennifer Barnes, Mathieu Renzo, V. Ashley Villar The core collapse of rapidly rotating massive ~10 Msun stars ("collapsars"), and resulting formation of hyper-accreting black holes, are a leading model for the central engines of long-duration gamma-ray bursts (GRB) and promising sources of r-process nucleosynthesis. I will discuss the signatures of collapsars from progenitors with extremely massive helium cores >130 Msun above the pair-instability mass gap. While rapid collapse to a black hole likely precludes a prompt explosion in these systems, I will demonstrate that disk outflows can generate a large quantity (up to >50 Msun) of ejecta, comprised of >5-10 Msun in r-process elements and ~0.1-1 Msun of 56Ni, expanding at velocities ~0.1c. Radioactive heating of the disk-wind ejecta powers an optical/infrared transient, with a characteristic luminosity ∼10^42 erg s−1 and spectral peak in the near-infrared (due to the high optical/UV opacities of lanthanide elements) similar to kilonovae from neutron star mergers, but with longer durations >= 1 month. These "super-kilonovae" (superKNe) herald the birth of massive black holes >60 Msun, which, as a result of disk wind mass-loss, can populate the pair-instability mass gap 'from above' and could potentially create the binary components of GW190521. SuperKNe could be discovered via wide-field surveys such as those planned with the Roman Space Telescope or via late-time infrared follow-up observations of extremely energetic GRBs. Gravitational waves of frequency ~0.1-50 Hz from non-axisymmetric instabilities in self-gravitating massive collapsar disks are potentially detectable by proposed third-generation intermediate and high-frequency observatories at distances up to hundreds of Mpc; in contrast to the "chirp" from binary mergers, the collapsar gravitational-wave signal decreases in frequency as the disk radius grows ("sad trombone"). |
Monday, April 24, 2023 6:24PM - 6:36PM |
JJ01.00003: Dedicated Core Collapse Supernovae search using the ML-enhanced Coherent WaveBurst search algorithm Justin J Perez, Sergey G Klimenko, Marek Szczepanczyk, Tanmaya Mishra Core Collapse supernovae (CCSN) are among the most powerful and interesting events within our universe. Along with electromagnetic and neutrino emissions, they are believed to produce a detectable gravitational wave (GW) signal. We are interested in detecting these multimessenger events in the hopes of being able to identify the morphology, and consequently the mechanism, of CCSN. The exact mechanism of CCSN is not known and so it is not known whether template searches will be able to identify these events effectively. In order to detect these GW signals without the use of templates, the Coherent WaveBurst (cWB) search algorithm is used to isolate coherent power in the data from the network of LIGO-Virgo GW detectors using the high-resolution Wavescan Time-Frequency (TF) mapping. cWB then uses a modified XGB based machine learning (ML) method to further distinguish real signal from noise. Here we present the working algorithm of the ML-enhanced cWB search for the use of CCSN detection. We also report the results of CCSN detection with cWB which was tested on the third observing run (O3) data of the LIGO-Virgo detectors. |
Monday, April 24, 2023 6:36PM - 6:48PM |
JJ01.00004: Optimal Feature Engineering for Exoplanet Parameter Retrievals Eyup Bedirhan Unlu, Roy T Forestano, Konstantin T Matchev, Katia Matcheva, Alexander Roman We use a blend of machine learning and theoretical methods for optimal minimum-loss compression of the input spectral data in retrieval algorithms of exoplanet parameters. The method is illustrated with retrievals from a synthetic database of 100,000 spectra of hot Jupiters representative of the expected Ariel target sensitivity. |
Monday, April 24, 2023 6:48PM - 7:00PM |
JJ01.00005: Turbulence from the Sun to the LISM Federico Fraternale, Lingling Zhao, Nikolai Pogorelov, Luca Sorriso-Valvo, Seth Redfield, Ming Zhang, Keyvan Ghanbari, Vladimir Florinski, Thomas Y. Chen Turbulence is ubiquitous in space plasmas. It is one of the most important subjects in heliospheric physics, as it plays a fundamental role in the solar wind - local interstellar medium interaction and in controlling energetic particle transport and acceleration processes. Understanding the properties of turbulence in various regions of the heliosphere with vastly different conditions can lead to answers to many unsolved questions opened up by observations of the magnetic field, plasma, pickup ions, energetic particles, radio and UV emissions, and so on. Several space missions have helped us gain preliminary knowledge on turbulence in the outer heliosphere and the very local interstellar medium. Among the past few missions, the Voyagers have paved the way for such investigations. This paper summarizes the open challenges and voices our support for the development of future missions dedicated to the study of turbulence throughout the heliosphere and beyond. |
Monday, April 24, 2023 7:00PM - 7:12PM |
JJ01.00006: Material Characterization of Digadolinium Trioxide Infused Conformal Coat for Use as Radiation Shielding Ryan J Charrette, Robert B Hayes The development of smaller nuclear technologies such as SMRs and an increased demand in space grade technologies due to the commercialization of space exploration demands new methods of compact shielding. A metal oxide infused conformal coat (MOICC) is being developed using gadolinium oxide as a material for radiation shielding. This shielding has potential for application in various aspects of industry, such as negating the need for radiation hardened (rad-hard) electronic components by allowing customers to opt for a commercial-off-the-shelf (COTS) part for a lower relative cost if externally shielded. The purpose of this project is to characterize various material properties for this novel shielding, specifically thermal conductivity, with an attempt to measure thermal expansion and electric resistivity. Results showed a promising increase in thermal conductivity with no measurable change in thermal expansion or electric resistivity using available equipment. Thermal conductivity saw an increase of up to 0.242 W/m-k using 50% metal oxide by mass. Electric resistivity was found to be at least 2 mega-ohms using a 2 mega-ohm rates multimeter. The method used for measuring thermal expansion was inadequate to develop meaningful values, though the theoretical bounds using the rule of mixtures is still reported. This report outlines the testing procedures and overall results for this material. |
Monday, April 24, 2023 7:12PM - 7:24PM |
JJ01.00007: Initialization of Compact Star Orbits Using External Potential Relaxation Scheme Michael Falato, Irina Sagert, Oleg Korobkin, Mark A Kaltenborn, Wesley Even Studying the mergers of compact-star binaries is essential for testing fundamental physics including the behavior of nuclear matter at high densities and in strong gravitational fields. Such studies are typically performed with computational fluid dynamics codes which require accurate initial conditions in regard to the shapes of each star in orbit to correctly model the inspiral phases and accretion flows. In this talk, we discuss a method which applies external potentials to relax binary neutron star and white dwarf configurations to be used as initial setups in Newtonian Smoothed Particle Hydrodynamics simulations. The external potential is defined so that the resulting forces which are experienced by the stars correspond to accelerations in a frame that is corotating with the binary. The forces deform each star to the configuration they should have, given a defined spin and orbital separation. We discuss the effectiveness of the method to produce stable Newtonian orbits as well as potential applications where we explore behavior of solid components in a neutron star's crust or core and their impact on the inspiral phase of a binary. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700