Search Publications
Is Flare Ribbon Fine Structure Related to Tearing in the Flare Current Sheet?
Wyper, P. F.; Pontin, D. I.
Observations of solar flare ribbons show significant fine structure in the form of breaking wavelike perturbations and spirals. The origin of this structure is not well understood, but one possibility is that it is related to the tearing instability in the flare current sheet. Here we study this connection by constructing an analytical 3D magnetic…
The RS CVn-type Star GT Mus Shows Most Energetic X-Ray Flares Throughout the 2010s
Hamaguchi, Kenji; Corcoran, Michael F.; Maeda, Yoshitomo +14 more
We report that the RS CVn-type star GT Mus (HR 4492, HD 101379+HD 101380) was the most active star in the X-ray sky in the last decade in terms of the scale of recurrent energetic flares. We detected 11 flares from GT Mus in 8 yr of observations with the Monitor of All-sky X-ray Image (MAXI) from 2009 August to 2017 August. The detected flare peak…
Unsupervised Machine Learning for the Identification of Preflare Spectroscopic Signatures
De Pontieu, Bart; Sainz Dalda, Alberto; Woods, Magnus M.
The study of the preflare environment is of great importance to understanding what drives solar flares. k-means clustering, an unsupervised machine-learning technique, has the ability to cluster large data set in a way that would be impractical or impossible for a human to do. In this paper we present a study using k-means clustering to identify p…
Exploring Mutual Information between IRIS Spectral Lines. II. Calculating the Most Probable Response in all Spectral Windows
Kleint, Lucia; Panos, Brandon
A three-dimensional picture of the solar atmosphere's thermodynamics can be obtained by jointly analyzing multiple spectral lines that span many formation heights. In Paper I, we found strong correlations between spectral shapes from a variety of different ions during solar flares in comparison to the quiet Sun. We extend these techniques to addre…
ENISALA. II. Distinct Star Formation and Active Galactic Nucleus Activity in Merging and Relaxed Galaxy Clusters
Sobral, David; Stroe, Andra
The growth of galaxy clusters is energetic and may trigger and/or quench star formation and black hole activity. The ENISALA4 project is a collection of multiwavelength observations aimed at understanding how large-scale structure drives galaxy and black hole evolution. Here, we introduce optical spectroscopy of over 800 Hα emission-lin…
RELICS: ICL Analysis of the z = 0.566 Merging Cluster WHL J013719.8-08284
Coe, Dan; Jiménez-Teja, Yolanda; Dupke, Renato A. +3 more
We present a pilot study of the intracluster light (ICL) in massive clusters using imaging of the z = 0.566 cluster of galaxies WHL J013719.8-08284 observed by the RELICS project with the Hubble Space Telescope. We measure the ICL fraction in four optical ACS/WFC filters (F435W, F475W, F606W, and F814W) and five infrared WFC3/IR bands (F105W, F110…
Three-dimensional Climate Simulations for the Detectability of Proxima Centauri b
Berrilli, Francesco; Giovannelli, Luca; Galuzzo, Daniele +2 more
The discovery of a planet orbiting around Proxima Centauri, the closest star to the Sun, opens new avenues for the remote observations of the atmosphere and surface of an exoplanet, Proxima b. To date, three-dimensional (3D) general circulation models (GCMs) are the best available tools to investigate the properties of the exo-atmospheres, waiting…
Molecular Gas within the Milky Way's Nuclear Wind
Richter, Philipp; Jenkins, Edward B.; Savage, Blair D. +9 more
We report the first direct detection of molecular hydrogen associated with the Galactic nuclear wind. The Far-Ultraviolet Spectroscopic Explorer spectrum of LS 4825, a B1 Ib-II star at l, b = 1.67°,-6.63° lying d = 9.9 ${}_{-0.8}^{+1.4}$ kpc from the Sun, ~1 kpc below the Galactic plane near the Galactic center, shows two high-velocity H2
A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). IV. Rapidly Growing (Super)Massive Black Holes in Extremely Radio-loud Galaxies
Lee, Chien-Hsiu; Schramm, Malte; Ueda, Yoshihiro +19 more
We present the optical and infrared properties of 39 extremely radio-loud galaxies discovered by cross-matching the Subaru/Hyper Suprime-Cam (HSC) deep optical imaging survey and VLA/FIRST 1.4 GHz radio survey. The recent Subaru/HSC strategic survey revealed optically faint radio galaxies (RG) down to gAB ~ 26, opening a new parameter s…
Cloud Properties of Brown Dwarf Binaries across the L/T Transition
Barman, Travis; Stone, Jordan M.; Konopacky, Quinn M. +1 more
We present a new suite of atmosphere models with flexible cloud parameters to investigate the effects of clouds on brown dwarfs across the L/T transition. We fit these models to a sample of 13 objects with well-known masses, distances, and spectral types spanning L3-T5. Our modeling is guided by spatially resolved photometry from the Hubble Space …