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 F14: Stellar births, deaths, and evolution |
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Sponsoring Units: DAP Chair: Brian Rauch, Washington University in St. Louis Room: Marquette V - 2nd Floor |
Sunday, April 16, 2023 8:30AM - 8:42AM |
F14.00001: Core-Collapse Supernovae: the role of the Si/O interface and the connection between explosion and progenitor structure. Luca Boccioli, Lorenzo Roberti, Marco Limongi, Grant J Mathews, Alessandro Chieffi The explosion mechanism of core-collapse supernovae has been a longstanding problem in nuclear astrophysics. In the last decade, important steps towards a thorough understanding of what causes supernovae to explode have been made, thanks to the development of very detailed three-dimensional simulations. However, a lot of work still needs to be done. In this talk, I will focus on the connection between the thermodynamic and compositional structure of the progenitor star and its subsequent explosion. I will use spherically symmetric simulations (where neutrino-driven convection is included via a mixing length approach) to simulate the collapse and shock revival of stars with different initial masses. I will highlight how discontinuities in the density profile at the onset of collapse can be used to predict the outcome of the explosion. Specifically, I will highlight the importance of neutrino-driven convection in triggering the explosion when these discontinuities are accreted through the shock. I will then briefly compare these results to the previous criterion by Ertl et al. (2016). Finally, I will comment on the differences between stellar evolution codes and reaction rates and how they can significantly change the explodability pattern of supernovae. |
Sunday, April 16, 2023 8:42AM - 8:54AM |
F14.00002: Characterizing the Directional Dependence of Gravitational Wave Emission from Core-collapse Supernovae Michael A Pajkos, Steven VanCamp, Kuo-Chuan Pan, Sean M Couch Core-collapse supernovae (CCSNe) enrich the universe with successively refined elements and new compact objects, with each generation of massive stars. One signal of interest from these stellar explosions are gravitational waves (GWs). These spacetime ripples encode interesting internal physics such as how matter behaves at nuclear densities, hydrodynamic activity, and neutrino production, among others. With a wealth of potential information from GWs, astronomers remain poised to interpret gravitational waveforms from these yet undetected sources. Beyond learning new kinds of physics, quantifying the directionality of GW emission is a crucial consideration with respect to observability. |
Sunday, April 16, 2023 8:54AM - 9:06AM |
F14.00003: Neutrino Quantum Kinetics with Moments in Neutron Star Mergers Sherwood A Richers, Evan Grohs, Sean M Couch, Francois V Foucart, James P Kneller, Gail C McLaughlin Core-collapse supernovae and neutron star mergers produce multimessenger transient signals that clue us in to the origin of the elements in the universe, the behavior of dense matter, and the nature of fundamental particles. Neutrinos of different flavors in these systems carry energy and lepton number, modifying the light, neutrino, and nucleosynthetic signature we see. Properly modeling this flavor transformation is extremely difficult, since flavor changing physics occurs on length scales of as small as millimeters, while the explosive dynamics occur on more than hundreds or kilometers. We simulate neutrino flavor transformation in a 3D cube extracted from a neutron star merger with two methods: an exact particle-in-cell simulation and an approximate two-moment simulation. We show that the resulting flavor instability is similar in both cases and reinforce the results with an analytic description of flavor instability in both cases. The ability of a moment method to exhibit such similar flavor instability suggests that self-consistent flavor transformation physics could become a standard component of future supernova and merger simulations. |
Sunday, April 16, 2023 9:06AM - 9:18AM Author not Attending |
F14.00004: Discovery of white dwarf companions of blue metal-poor stars using UVIT/AstroSat Anju Panthi, Kaushar Vaidya, Annapurni Subramaniam, Vikrant Jadhav, Sharmila Rani, Sindhu Pandey, Snehalata Sahu, Sivarani Thirupathi Blue metal-poor (BMP) stars are main-sequence stars that appear bluer and more luminous than normal turn-off stars of metal-poor globular clusters. These stars are believed to be either field blue straggler stars (FBSS) formed via post mass transfer mechanism or accreted from dwarf satellite galaxies of the Milky Way. A significant fraction of BMP stars are discovered to be binaries, typically with long periods and circular orbits, likely to have a compact companion. UVIT/AstroSat has observed 27 BMP stars in two FUV filters, F148W and F169M. We report the first ever discovery of white dwarfs companions in 14 stars. Out of these 14 stars, 10 are known to be either single-lined spectroscopic binaries or binary candidates with the periods of 0.9 to 840 days and eccentricity 0 to 0.5. 3 BMP stars are known to be radial velocity constant stars. We suspect that orbits of these stars may be either inclined or distance between binaries may be too large to observe the variation in radial velocities. For the remaining 1 star, no previous information on binarity is available. The hot companions with estimated temperatures, Teff ∼ 10500 − 40000 K, are white dwarfs (WDs) of extremely low-mass (∼ 0.20 M_sun), low-mass (∼ 0.20 – 0.40 M_sun), normal mass (∼ 0.40 – 0.60 M_sun), and high-mass (∼ 0.8M_sun). Our analysis suggests that both mass transfer and merger in hierarchial triple system channels play a major role in the formation of BMP stars and thus atleast 14 BMP stars in our sample are confirmed FBSS. |
Sunday, April 16, 2023 9:18AM - 9:30AM |
F14.00005: Investigating Milky Way Red Supergiants Sarah Healy Archival pre-explosion images have shown red supergiants (RSGs) to be the direct progenitors of the most common core-collapse SN, Type-IIP. However, the current number of known RSGs in the Milky Way is not substantial, with most catalogs having ~100. A better understanding of the spatial and luminosity distribution of RSGs will help not only with understanding galactic stellar evolution but also improve our chances of having pre-explosion images and our ability to utilize multimessenger astronomy during core collapse. We used two methods to compile spectroscopically derived spectral type catalogs and estimated the stellar bolometric magnitudes. Along with the stellar luminosity of each candidate, we use various parameters, including a comparison to massive star evolutionary tracks, status as a multi-star system, and evidence of variability, which match the characteristics of RSGs to determine the likelihood for each. We also look into our ability, with current detectors and those soon to be online, to resolve the position of each candidate if we received a neutrino signal. |
Sunday, April 16, 2023 9:30AM - 9:42AM |
F14.00006: Evolutionary Origins of Binary Neutron Star Mergers: Effects of Common Envelope Efficiency and Metallicity Monica Gallegos-Garcia, Christopher P Berry, Vicky Kalogera The formation histories of compact binary mergers, especially stellar-mass binary-black hole mergers, have recently come under increased scrutiny and revision. We revisit the question of the dominant formation channel and efficiency of forming binary neutron-star mergers. We use the stellar and binary evolution code MESA and implement a detailed method for common envelope and mass transfer. We preform simulations for donor masses between 8-20 solar masses with a neutron star companion of 1.4 and 2.0 solar masses at two metallicities, using varying common envelope efficiencies, and two prescriptions to determine if the donor undergoes core-collapse or electron-capture. In contrast to the case of binary-black hole mergers, for a neutron star companion of 1.4 solar masses, all binary neutron star mergers are formed following a common envelope phase, while for a neutron star mass of 2.0 solar masses we identify a small subset of mergers following only stable mass transfer if the neutron star receives a strong supernova natal kick. Regardless of neutron star companion mass, we find that these stronger supernova natal kicks are favored in the formation of binary neutron star mergers, and find more mergers at subsolar metallicity compared to solar. |
Sunday, April 16, 2023 9:42AM - 9:54AM |
F14.00007: Fast Rotating Low-mass Stars from Post Mass-transfer and Post Wind Mass-transfer Binary Systems Meng Sun, Seth Gossage, Sasha Levina, Vicky Kalogera, Zoheyr Doctor More than half of stars are in a binary system. When the two stars are close, the donor star could transfer mass onto the accretor star through the inner Lagrangian point, where the Roche-lobe of the two stars meets. Other than mass, angular momentum is transferred which can spin-up the rotation of the accretor star. In a recent work of long-term spectroscopy binary survey, several fast rotating post mass-transfer stars in young open clusters have been found. In this work, we use the infrastructure functionality in POpulation SYnthesis with Detailed binary-evolution simulatiONs (POSYDON, the next generation binary population synthesis code based on the MESA detailed binary evolutionary simulations), to establish a big low-mass binary grid focusing on the rotation of the accretor star. State-of-the-art magnetic braking presciptions are implemented to explain the data and the possible assistance in stellar gyrochronology in telling the age of those systems. In addition, we find that accretion through wind mass-transfer or even a small amount of mass through regular mass-transfer can account for the fast rotation measurements. |
Sunday, April 16, 2023 9:54AM - 10:06AM |
F14.00008: Modeling galactic Be X-ray binaries with POSYDON Kyle A Rocha, Vicky Kalogera, Zoheyr Doctor, Jeff Andrews X-ray binaries (XBRs) are testbeds for modeling binary and stellar evolution. Be XRBs are the most numerous subclass of observed high-mass XRBs, containing Be donors with neutron star (NS) and black hole (BH) companions. While the exact mechanism responsible for the Be phenomenon remains under debate, stellar rotation has been identified as a key ingredient for the formation of the decretion disk. Previous population synthesis studies have used the Be XRB population to constrain binary evolution processes such as mass transfer and common envelope efficiency, but without selection criteria coming from rotational modeling. We use POSYDON, a next generation population synthesis code coupled with binary MESA models, to study galactic Be XRBs. For the first time, we model the rotational evolution of the donor and use prescriptions for the decretion disk to select Be XRB like systems. We can successfully match both the orbital properties of the observed sample of Be XRBs, as well as the relative abundance of NS to BH BeXRBs. Our results demonstrate the necessity of accurately modeling stellar rotation to interpret the Be XRB population. |
Sunday, April 16, 2023 10:06AM - 10:18AM |
F14.00009: A Study of Jupiter-Like Exoplanets Magnetosphere Interactions with Stellar Winds using MHD Simulations Fatemeh Bagheri, Ramon E Lopez, Kevin Pham Numerous numerical studies have been carried out in recent years that simulate different aspects of Star-Planet Interactions. These studies focus mostly on hot Jupiters with sun-like stars. However, more realistic simulations require the inclusion of a wide range of stellar types in the study of stellar-planetary interactions. In this study, I use MHD simulations to model star-planet interactions assuming different stellar types with Jupiter-like planets. In this talk, I will present some results of the structures and dynamics of the magnetospheres of these kinds of systems. |
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