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Observation of the radiation environment and solar energetic particle events in Mars orbit in May 2018- June 2022
Gopalswamy, Nat; Semkova, Jordanka; Koleva, Rositza +19 more
The dosimeter Liulin-MO for measuring the radiation environment onboard the ExoMars Trace Gas Orbiter (TGO) is a module of the Fine Resolution Epithermal Neutron Detector (FREND). Here we present results from measurements of the charged particle fluxes, dose rates and estimation of dose equivalent rates at ExoMars TGO Mars science orbit, provided …
Constraining dark matter interactions mediated by a light scalar with white dwarfs
Ramirez-Quezada, Maura E.
Observations of white dwarfs in dark matter-rich environments can provide strong limits on the strength of dark matter interactions. Here we apply the recently improved formalism of the dark matter capture rate in white dwarfs to a general model in which dark matter interacts with the white dwarf ion components via a light scalar mediator. We comp…
Metallicity-PAH Relation of MIR-selected Star-forming Galaxies in AKARI North Ecliptic Pole-wide Survey
Hashimoto, Tetsuya; Jeong, Woong-Seob; Hwang, Ho Seong +9 more
We investigate the variation in the mid-infrared spectral energy distributions of 373 low-redshift (z < 0.4) star-forming galaxies, which reflects a variety of polycyclic aromatic hydrocarbon (PAH) emission features. The relative strength of PAH emission is parameterized as q PAH, which is defined as the mass fraction of PAH particle…
Unveiling the gravitationally unstable disc of a massive star-forming galaxy using NOEMA and MUSE
Cannon, John M.; Hayes, Matthew; Östlin, Göran +7 more
Using new high-resolution data of CO (2-1), H$\alpha$ and H$\beta$ obtained with the Northern Extended Millimeter Array (NOEMA) and the Multi-Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope, we have performed a Toomre Q disc stability analysis and studied star formation, gas depletion times and other environmental parameters on sub-…
Classification of Chandra X-Ray Sources in Cygnus OB2
Naylor, Tim; Drake, Jeremy J.; Wright, Nicholas J. +11 more
We have devised a predominantly Naive Bayes-based method to classify X-ray sources detected by Chandra in the Cygnus OB2 association into members, foreground objects, and background objects. We employ a variety of X-ray, optical, and infrared characteristics to construct likelihoods using training sets defined by well-measured sources. Combination…
The age, kinematics, and metallicity of nearby Sun-like stars and the history of the Milky Way disc
Gondoin, P.
Contact. Investigating how the Milky Way formed and has evolved is an important topic in astrophysics that requires the determination of precise ages for large samples of stars over long periods.
Aims: The present study addresses the formation history of nearby Sun-like stars using the emission reversal in the cores of their Ca II H&K Fra…
The Direct-method Oxygen Abundance of Typical Dwarf Galaxies at Cosmic High Noon
Richard, Johan; Siana, Brian; Freeman, William R. +5 more
We present a Keck/MOSFIRE rest-optical composite spectrum of 16 typical gravitationally lensed star-forming dwarf galaxies at 1.7 ≲ z ≲ 2.6 (z mean = 2.30), all chosen independent of emission-line strength. These galaxies have a median stellar mass of $\mathrm{log}{({M}_{* }/{M}_{\odot })}_{\mathrm{med}}={8.29}_{-0.43}^{+0.51}$ and a me…
Varstrometry for Off-nucleus and Dual Sub-kiloparsec Active Galactic Nuclei (VODKA): Very Long Baseline Array Searches for Dual or Off-nucleus Quasars and Small-scale Jets
Shen, Yue; Zakamska, Nadia L.; Lazio, Joseph +5 more
Dual and off-nucleus active supermassive black holes are expected to be common in the hierarchical structure formation paradigm, but their identification at parsec scales remains a challenge due to strict angular resolution requirements. We conducted a systematic study using the Very Long Baseline Array (VLBA) to examine 23 radio-bright candidate …
Dynamical masses and ages of Sirius-like systems
Kiman, Rocio; Brandt, Timothy D.; Li, Yiting +4 more
We measure precise orbits and dynamical masses and derive age constraints for six confirmed and one candidate Sirius-like systems, including the Hyades member HD 27483. Our orbital analysis incorporates radial velocities, relative astrometry, and Hipparcos-Gaia astrometric accelerations. We constrain the main-sequence lifetime of a white dwarf's p…
Evolution of the Radial Size and Expansion of Coronal Mass Ejections Investigated by Combining Remote and In Situ Observations
Lugaz, Noé; Zhuang, Bin; Scolini, Camilla +4 more
A fundamental property of coronal mass ejections (CMEs) is their radial expansion, which determines the increase in the CME radial size and the decrease in the CME magnetic field strength as the CME propagates. CME radial expansion can be investigated either by using remote observations or by in situ measurements based on multiple spacecraft in ra…