Coronal Response to Magnetically Suppressed CME Events in M-dwarf Stars
AuthorAlvarado-Gómez, Julián D.
Drake, Jeremy J.
Moschou, Sofia P.
Yadav, Rakesh K.
Stellar coronal mass ejections
Stellar mass loss
Stellar magnetic fields
Stellar coronal dimming
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationJulián D. Alvarado-Gómez et al 2019 ApJL 884 L13
JournalASTROPHYSICAL JOURNAL LETTERS
RightsCopyright © 2019. The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractWe report the results of the first state-of-the-art numerical simulations of coronal mass ejections (CMEs) taking place in realistic magnetic field configurations of moderately active M-dwarf stars. Our analysis indicates that a clear, novel, and observable, coronal response is generated due to the collapse of the eruption and its eventual release into the stellar wind. Escaping CME events, weakly suppressed by the large-scale field, induce a flare-like signature in the emission from coronal material at different temperatures due to compression and associated heating. Such flare-like profiles display a distinctive temporal evolution in their Doppler shift signal (from red to blue), as the eruption first collapses toward the star and then perturbs the ambient magnetized plasma on its way outwards. For stellar fields providing partial confinement, CME fragmentation takes place, leading to rise and fall flow patterns which resemble the solar coronal rain cycle. In strongly suppressed events, the response is better described as a gradual brightening, in which the failed CME is deposited in the form of a coronal rain cloud leading to a much slower rise in the ambient high-energy flux by relatively small factors (~2–3). In all the considered cases (escaping/confined) a fractional decrease in the emission from midrange coronal temperature plasma occurs, similar to the coronal dimming events observed on the Sun. Detection of the observational signatures of these CME-induced features requires a sensitive next generation X-ray space telescope.
NoteOpen access article
VersionFinal published version
SponsorsNational Aeronautics & Space Administration (NASA) [NAS8-03060]; NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center; NASA's Pleiades cluster [SMD-17-1330]; National Science Foundation (NSF) [ACI-1548562]; NASA Living with a Star grant [NNX16AC11G]; [Chandra GO5-16021X]; [HST GO-15326]
Except where otherwise noted, this item's license is described as Copyright © 2019. The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.
Showing items related by title, author, creator and subject.
Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. II. A New Class of Stellar SystemJones, M.G.; Sand, D.J.; Bellazzini, M.; Spekkens, K.; Karunakaran, A.; Adams, E.A.K.; Battaglia, G.; Beccari, G.; Bennet, P.; Cannon, J.M.; et al. (Institute of Physics, 2022)We discuss five blue stellar systems in the direction of the Virgo cluster, analogous to the enigmatic object SECCO 1 (AGC 226067). These objects were identified based on their optical and UV morphology and followed up with H i observations with the Very Large Array (and Green Bank Telescope), Multi Unit Spectroscopic Explorer (on the Very Large Telescope) optical spectroscopy, and Hubble Space Telescope imaging. These new data indicate that one system is a distant group of galaxies. The remaining four are extremely low mass (M * ∼ 105 M ⊙), are dominated by young blue stars, have highly irregular and clumpy morphologies, are only a few kiloparsecs across, yet host an abundance of metal-rich, 12 + log ( O / H ) > 8.2 , H ii regions. These high metallicities indicate that these stellar systems formed from gas stripped from much more massive galaxies. Despite the young age of their stellar populations, only one system is detected in H i, while the remaining three have minimal (if any) gas reservoirs. Furthermore, two systems are surprisingly isolated and have no plausible parent galaxy within ∼30′ (∼140 kpc). Although tidal stripping cannot be conclusively excluded as the formation mechanism of these objects, ram pressure stripping more naturally explains their properties, in particular their isolation, owing to the higher velocities, relative to the parent system, that can be achieved. Therefore, we posit that most of these systems formed from ram-pressure-stripped gas removed from new infalling cluster members and survived in the intracluster medium long enough to become separated from their parent galaxies by hundreds of kiloparsecs and that they thus represent a new type of stellar system. © 2022. The Author(s). Published by the American Astronomical Society.
Stellar Energetic Particle Transport in the Turbulent and CME-disrupted Stellar Wind of AU MicroscopiiFraschetti, F.; Alvarado-Gómez, J.D.; Drake, J.J.; Cohen, O.; Garraffo, C.; Department of Planetary Sciences-Lunar and Planetary Laboratory, University of Arizona (Institute of Physics, 2022)Energetic particles emitted by active stars are likely to propagate in astrospheric magnetized plasma and disrupted by the prior passage of energetic coronal mass ejections (CMEs). We carried out test-particle simulations of ∼GeV protons produced at a variety of distances from the M1Ve star AU Microscopii by coronal flares or traveling shocks. Particles are propagated within a large-scale quiescent three-dimensional magnetic field and stellar wind reconstructed from measured magnetograms, and within the same stellar environment following the passage of a 1036 erg kinetic energy CME. In both cases, magnetic fluctuations with an isotropic power spectrum are overlayed onto the large-scale stellar magnetic field and particle propagation out to the two innnermost confirmed planets is examined. In the quiescent case, the magnetic field concentrates the particles into two regions near the ecliptic plane. After the passage of the CME, the closed field lines remain inflated and the reshuffled magnetic field remains highly compressed, shrinking the scattering mean free path of the particles. In the direction of propagation of the CME lobes the subsequent energetic particle (EP) flux is suppressed. Even for a CME front propagating out of the ecliptic plane, the EP flux along the planetary orbits highly fluctuates and peaks at ∼2-3 orders of magnitude higher than the average solar value at Earth, both in the quiescent and the post-CME cases. © 2022. The Author(s). Published by the American Astronomical Society.
Stellar masses, sizes, and radial profiles for 465 nearby early-Type galaxies: An extension to the Spitzer survey of stellar structure in Galaxies (S4G)Watkins, A.E.; Salo, H.; Laurikainen, E.; Díaz-García, S.; Comerón, S.; Janz, J.; Su, A.H.; Buta, R.; Athanassoula, E.; Bosma, A.; et al. (EDP Sciences, 2022)Context. The Spitzer Survey of Stellar Structure in Galaxies (S4G) is a detailed study of over 2300 nearby galaxies in the near-infrared (NIR), which has been critical to our understanding of the detailed structures of nearby galaxies. Because the sample galaxies were selected only using radio-derived velocities, however, the survey favored late-Type disk galaxies over lenticulars and ellipticals. Aims. A follow-up Spitzer survey was conducted to rectify this bias, adding 465 early-Type galaxies (ETGs) to the original sample, to be analyzed in a manner consistent with the initial survey. We present the data release of this ETG extension, up to the third data processing pipeline (P3): surface photometry. Methods. We produce curves of growth and radial surface brightness profiles (with and without inclination corrections) using reduced and masked Spitzer IRAC 3.6 μm and 4.5 μm images produced through Pipelines 1 and 2, respectively. From these profiles, we derive the following integrated quantities: Total magnitudes, stellar masses, concentration parameters, and galaxy size metrics. We showcase NIR scaling relations for ETGs among these quantities. Results. We examine general trends across the whole S4G and ETG extension among our derived parameters, highlighting differences between ETGs and late-Type galaxies (LTGs). The latter are, on average, more massive and more concentrated than LTGs, and subtle distinctions are seen among ETG morphological subtypes. We also derive the following scaling relations and compare them with previous results in visible light: mass-size (both half-light and isophotal), mass-concentration, mass-surface brightness (central, effective, and within 1 kpc), and mass-color. Conclusions. We find good agreement with previous works, though some relations (e.g., mass-central surface brightness) will require more careful multicomponent decompositions to be fully understood. The relations between mass and isophotal radius and between mass and surface brightness within 1 kpc, in particular, show notably small scatter. The former provides important constraints on the limits of size growth in galaxies, possibly related to star formation thresholds, while the lattera-particularly when paired with the similarly tight relation for LTGs-showcases the striking self-similarity of galaxy cores, suggesting they evolve little over cosmic time. All of the profiles and parameters described in this paper will be provided to the community via the NASA/IPAC database on a dedicated website. © ESO 2022.