Search Publications
Multiwavelength Observations of a Jet Launch in Real Time from the Post-changing-look Active Galaxy 1ES 1927+654
Ingram, Adam; Cenko, S. Bradley; Ricci, Claudio +34 more
We present results from a high-cadence multiwavelength observational campaign of the enigmatic changing-look active galactic nucleus 1ES 1927+654 from 2022 May to 2024 April, coincident with an unprecedented radio flare (an increase in flux by a factor of ∼60 over a few months) and the emergence of a spatially resolved jet at 0.1–0.3 pc scales. Co…
Dynamical Models of the Milky Way in Action Space with LAMOST DR8 and Gaia EDR3
Zhang, Xin; Mao, Shude; Chen, Xuelei +6 more
This work explores dynamical models of the Milky Way (MW) by analyzing a sample of 86,109 K giant stars selected through cross-matching the LAMOST DR8 and Gaia EDR3 surveys. Our earlier torus models of Q. Wang et al. did not include Gaia data, making them incompatible with the new sample's proper motion distributions. Here, we refine the construct…
Persistence and Burn-in in Solar Coronal Magnetic Field Simulations
Meyer, Karen A.; Yeates, Anthony R.; Hall, Eric J.
Simulations of solar phenomena play a vital role in space-weather prediction. A critical computational question for automating research workflows in the context of data-driven solar coronal magnetic field simulations is quantifying a simulation's burn-in time, after which a solar quantity has evolved away from an arbitrary initial condition to a p…
Transonic Turbulence and Density Fluctuations in the Near-Sun Solar Wind
Li, H.; Zank, G. P.; Zhao, L. -L. +2 more
We use in situ measurements from the first 19 encounters of Parker Solar Probe and the most recent five encounters of Solar Orbiter to study the evolution of the turbulent sonic Mach number Mt (the ratio of the amplitude of velocity fluctuations to the sound speed) with radial distance and its relationship to density fluctuations. We fo…
The Initial-to-final Mass Relation of White Dwarfs in Intermediate-separation Binaries
Hallakoun, Na'ama; Shahaf, Sahar; Ben-Ami, Sagi +1 more
We examine the applicability of the initial-to-final mass relation (IFMR) for white dwarfs (WDs) in intermediate-separation binary systems (∼1 au), using astrometric binaries identified in open clusters from Gaia DR3. A careful analysis of the astrometric orbits and spectral energy distributions isolates 33 main-sequence (MS) stars with highly lik…
Testing the Universality of Self-organized Criticality in Galactic, Extragalactic, and Black Hole Systems
Göǧüş, Ersin; Aschwanden, Markus J.
In this study, we test whether the power law slopes (α F ) for fluxes (F), and (α E ) for energies (E) are universal in their size distributions,
Magnetic Activity Evolution of Solar-like Stars. II. Sph–Ro Evolution of Kepler Main-sequence Targets
van Saders, Jennifer; García, Rafael A.; Breton, Sylvain N. +16 more
There is now a large sample of stars observed by the Kepler satellite with measured rotation periods and photometric activity index Sph. We use this data, in conjunction with stellar interiors models, to explore the interplay of magnetism, rotation, and convection. Stellar activity proxies other than Sph are correlated with t…
Estimating the Mass Escaping Rates of Radius-valley-spanning Planets in the TOI-431 System via X-Ray and Ultraviolet Evaporation
Zhu, Zong-Hong; Jiang, Xiaoming; Jiang, Jonathan H. +1 more
The TOI-431 system has three close-in exoplanets, which gives an ideal lab to study gas escape. In this study, we measure the X-ray and ultraviolet luminosity for TOI-431 with XMM-Newton's European Photon Imaging Camera-pn and Optical/UV Monitor Telescope data, then calculate the fluxes for the planets in the system. We find TOI-431 b's
A Time-dependent Spectral Analysis of γ Cassiopeiae
Nichols, Joy S.; Huenemoerder, David P.; Ignace, Richard +7 more
We investigated the temporal and spectral features of γ Cassiopeiae's X-ray emission within the context of the white dwarf (WD) accretion hypothesis. We find that the variabilities present in the X-ray data show two different signals, one primarily due to absorption and the other due to flickering like in nonmagnetic cataclysmic variables. We then…
Can the Central Compact Object in HESS J1731–347 Be Indeed the Lightest Neutron Star Observed?
Zhang, S. R.; Rueda Hernandez, J. A.; Negreiros, R.
The exceptionally low mass of