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Investigating Europa's Radiation Environment with the Europa Clipper Radiation Monitor
McEwen, Alfred; Clark, Roger; Paranicas, Chris +23 more
We present an overview of the radiation environment monitoring program planned for the Europa Clipper mission. The harsh radiation environment of Jupiter will be measured by a dedicated Radiation Monitor (RadMon) subsystem, yielding mission accumulative Total Ionizing Dose (TID) and instantaneous electron flux measurements with a 1-Hz cadence. The…
Influence of Solar Wind Variations on the Shapes of Venus' Plasma Boundaries Based on Venus Express Observations
André, N.; Fedorov, A.; Futaana, Y. +10 more
The interaction between the solar wind and Venus creates an induced magnetosphere. The regions of the induced magnetosphere are separated by plasma boundaries, where their shapes and sizes are influenced by variations in the surrounding environment. Investigations of the boundaries and their variability can help us understand the solar wind's effe…
MOSEL Survey: JWST Reveals Major Mergers/strong Interactions Drive the Extreme Emission Lines in the Early Universe
Harshan, Anishya; Kacprzak, Glenn G.; Nanayakkara, Themiya +7 more
Extreme emission line galaxies (EELGs), where nebular emissions contribute 30%-40% of the flux in certain photometric bands, are ubiquitous in the early Universe (z > 6). We utilize deep NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) to investigate the properties of companion galaxies (projected distance <40 kpc, ∣dv…
Magnetic helicity and free magnetic energy as tools for probing eruptions in two differently evolving solar active regions
Georgoulis, M. K.; Nindos, A.; Liokati, E.
Aims: We study the role of magnetic helicity and free magnetic energy in the initiation of eruptions in two differently evolving solar active regions (ARs).
Methods: Using vector magnetograms from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and a magnetic connectivity-based method, we calculate the instan…
Freezing in vector dark matter through magnetic dipole interactions
Krnjaic, Gordan; Rocha, Duncan; Sokolenko, Anastasia
We study a simple model of vector dark matter that couples to Standard Model particles via magnetic dipole interactions. In this scenario, the cosmological abundance arises through the freeze-in mechanism and depends on the dipole coupling, the vector mass, and the reheat temperature. To ensure cosmological metastability, the vector must be lighte…
VaTEST I: validation of sub-Saturn exoplanet TOI-181b in narrow orbit from its host star
Bieryla, Allyson; Esquerdo, Gilbert A.; Beichman, Charles A. +10 more
We present here a validation of sub-Saturn exoplanet TOI-181b orbiting a K spectral type star TOI-181 (mass: 0.822 ± 0.04 M⊙, radius: 0.745 ± 0.02 R⊙, temperature: 4994 ± 50 K) as a part of Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project. TOI-181b is a planet with radius 6.95 ± 0.08 R⊕,…
Uranium Abundances and Ages of r-process Enhanced Stars with Novel U II Lines
Beers, Timothy C.; Holmbeck, Erika M.; Hansen, Terese T. +7 more
The ages of the oldest stars shed light on the birth, chemical enrichment, and chemical evolution of the universe. Nucleocosmochronometry provides an avenue to determining the ages of these stars independent from stellar-evolution models. The uranium abundance, which can be determined for metal-poor r-process enhanced (RPE) stars, has been known t…
Astrometric microlensing of primordial black holes with Gaia
Rentala, Vikram; Verma, Himanshu
The Gaia space telescope allows for unprecedented accuracy for astrometric measurements of stars in the Galaxy. In this work, we explore the sensitivity of Gaia to detect primordial black hole (PBH) dark matter through the distortions that PBHs would create in the apparent trajectories of background stars, an effect known as astrometric microlensi…
Exploring Stellar Cluster and Feedback-driven Star Formation in the Galactic Mid-infrared Bubble [HKS2019] E70
Pandey, Rakesh; Sharma, Saurabh; Dewangan, Lokesh +8 more
We present a comprehensive analysis of the Galactic mid-infrared bubble [HKS2019] E70 (E70) by adopting a multiwavelength approach to understand the physical environment and star formation scenario around it. We identified a small (radius ~1.7 pc) stellar cluster inside the E70 bubble, and its distance is estimated as 3.26 ± 0.45 kpc. This cluster…
The GW Vir Instability Strip in Light of New Observations of PG 1159 Stars: Discovery of Pulsations in the Central Star of A72 and Variability of RX J0122.9-7521
Jones, David; Karjalainen, Marie; Caldwell, John A. R. +9 more
We present the results of new time-series photometric observations of 29 pre-white dwarf stars of PG 1159 spectral type, carried out in the years 2014-2022. For the majority of stars, a median noise level in Fourier amplitude spectra of 0.5-1.0 mmag was achieved. This allowed the detection of pulsations in the central star of planetary nebula A72 …