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Group Sunspot Numbers: A New Reconstruction of Sunspot Activity Variations from Historical Sunspot Records Using Algorithms from Machine Learning
Velasco Herrera, Víctor Manuel; Soon, Willie; Hoyt, Douglas V. +1 more
Historical sunspot records and the construction of a comprehensive database are among the most sought after research activities in solar physics. Here, we revisit the issues and remaining questions on the reconstruction of the so-called group sunspot numbers (GSN) that was pioneered by D. Hoyt and colleagues. We use the modern tools of artificial …
The signature of large-scale turbulence driving on the structure of the interstellar medium
Robitaille, Jean-François; Glover, Simon C. O.; Klessen, Ralf S. +9 more
The mechanisms that maintain turbulence in the interstellar medium (ISM) are still not identified. This work investigates how we can distinguish between two fundamental driving mechanisms: the accumulated effect of stellar feedback versus the energy injection from galactic scales. We perform a series of numerical simulations describing a stratifie…
Global Vertical Distribution of Water Vapor on Mars: Results From 3.5 Years of ExoMars-TGO/NOMAD Science Operations
Aoki, S.; Vandaele, A. C.; Daerden, F. +20 more
We present water vapor vertical distributions on Mars retrieved from 3.5 years of solar occultation measurements by Nadir and Occultation for Mars Discovery onboard the ExoMars Trace Gas Orbiter, which reveal a strong contrast between aphelion and perihelion water climates. In equinox periods, most of water vapor is confined into the low-middle la…
Evolution of X-Ray Activity in <25 Myr Old Pre-main Sequence Stars
Garmire, Gordon P.; Feigelson, Eric D.; Broos, Patrick S. +4 more
Measuring the evolution of X-ray emission from pre-main-sequence (PMS) stars gives insight into two issues: the response of magnetic dynamo processes to changes in the interior structure, and the effects of high-energy radiation on protoplanetary disks and primordial planetary atmospheres. We present a sample of 6003 stars with ages 7-25 Myr in 10…
Directly Tracing Cool Filamentary Accretion over >100 kpc into the Interstellar Medium of a Quasar Host at z = 1
Johnson, Sean D.; Kollatschny, Wolfram; Chen, Hsiao-Wen +10 more
We report the discovery of giant (50-100 kpc) [O II] emitting nebulae with MUSE in the field of TXS 0206-048, a luminous quasar at z = 1.13. "Down-the-barrel" UV spectra of the quasar show absorption at velocities coincident with those of the extended nebulae, enabling new insights into inflows and outflows around the quasar host. One nebula exhib…
Barium stars as tracers of s-process nucleosynthesis in AGB stars. I. 28 stars with independently derived AGB mass
Pereira, C. B.; Cseh, B.; D'Orazi, V. +7 more
Context. Barium (Ba) stars are polluted by material enriched in the slow neutron capture (s-process) elements synthesised in the interior of their former asymptotic giant branch (AGB) companion star, which is now a white dwarf.
Aims: We aim to compare individual Ba star abundance patterns to AGB nucleosynthesis model predictions to verify if …
Accretion variability from minute to decade timescales in the classical T Tauri star CR Cha
Pál, A.; Ábrahám, P.; Kóspál, Á. +6 more
Context. Classical T Tauri stars are pre-main-sequence stars that are surrounded by a circumstellar disk from which they accrete material. The mass accretion process is essential in the formation of Sun-like stars. Although often described with simple and static models, the accretion process is inherently time variable.
Aims: We examine the a…
The supernova remnant SN 1006 as a Galactic particle accelerator
Greco, Emanuele; Vink, Jacco; Miceli, Marco +6 more
The origin of cosmic rays is a pivotal open issue of high-energy astrophysics. Supernova remnants are strong candidates to be the Galactic factory of cosmic rays, their blast waves being powerful particle accelerators. However, supernova remnants can power the observed flux of cosmic rays only if they transfer a significant fraction of their kinet…
Probing the Galactic halo with RR Lyrae stars - II. The substructures of the Milky Way
Huang, Y.; Zhang, H. -W.; Zhang, L. +4 more
We identify substructures of the Galactic halo using 3003 type ab RR Lyrae stars with six-dimensional position-velocity information from the Sloan Digital Sky Survey, the Large Sky Area Multi-Object Fiber Spectroscopic Telescope and the Gaia Early Data Release 3. Based on this information, we define the separation of any two of the stars in the in…
The MBHBM⋆ Project - II. Molecular gas kinematics in the lenticular galaxy NGC 3593 reveal a supermassive black hole
Baba, Shunsuke; Imanishi, Masatoshi; Neumayer, Nadine +15 more
As part of the Measuring Black Holes in below Milky Way-mass (M⋆) galaxies (MBHBM⋆) Project, we present a dynamical measurement of the supermassive black hole (SMBH) mass in the nearby lenticular galaxy NGC 3593, using cold molecular gas 12CO(2-1) emission observed at an angular resolution of ≈0${_{.}^{\prime\prime…