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CME-driven Shock and Type II Solar Radio Burst Band Splitting
Temmer, Manuela; Kontar, Eduard P.; Chrysaphi, Nicolina +1 more
Coronal mass ejections (CMEs) are believed to be effective in producing shocks in the solar corona and interplanetary space. One of the important signatures of shocks and shock acceleration are Type II solar radio bursts that drift with the shock speed and produce bands of fundamental and higher harmonic plasma radio emission. An intriguing aspect…
IRIS and SDO Observations of Solar Jetlets Resulting from Network-edge Flux Cancelation
Tiwari, Sanjiv K.; De Pontieu, Bart; Panesar, Navdeep K. +3 more
Recent observations show that the buildup and triggering of minifilament eruptions that drive coronal jets result from magnetic flux cancelation at the neutral line between merging majority- and minority-polarity magnetic flux patches. We investigate the magnetic setting of 10 on-disk small-scale UV/EUV jets (jetlets, smaller than coronal X-ray je…
Statistical Analysis of Torus and Kink Instabilities in Solar Eruptions
Xu, Yan; Liu, Chang; Jing, Ju +4 more
A recent laboratory experiment of ideal magnetohydrodynamic instabilities revealed four distinct eruption regimes readily distinguished by the torus instability (TI) and helical kink instability (KI) parameters. To establish its observational counterpart, we collected 38 solar flares (stronger than GOES-class M5 in general) that took place within …
HelMod in the Works: From Direct Observations to the Local Interstellar Spectrum of Cosmic-Ray Electrons
Jóhannesson, G.; Moskalenko, I. V.; Porter, T. A. +11 more
The local interstellar spectrum (LIS) of cosmic-ray (CR) electrons for the energy range 1 MeV to 1 TeV is derived using the most recent experimental results combined with the state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. Two propagation packages, GALPROP and HELMOD, are combined to provide a single framework that…
MAGIICAT VI. The Mg II Intragroup Medium Is Kinematically Complex
Kacprzak, Glenn G.; Churchill, Christopher W.; Nielsen, Nikole M. +2 more
By comparing Mg II absorption in the circumgalactic medium (CGM) of group environments to isolated galaxies, we investigated the impact of environment on the CGM. An Mg II absorber is associated with a group if there are two or more galaxies at the absorption redshift within a projected distance of D = 200 kpc from a background quasar and a line-o…
Distances to the Globular Clusters 47 Tucanae and NGC 362 Using Gaia DR2 Parallaxes
Caiazzo, Ilaria; Chen, Seery; Heyl, Jeremy +1 more
Using parallaxes from Gaia Data Release 2 (Gaia DR2), we estimate the distance to the globular clusters 47 Tuc and NGC 362, taking advantage of the background stars in the Small Magellanic Cloud and quasars to account for various parallax systematics. We found the parallax to be dependent on the Gaia DR2 G-band apparent magnitude for stars with 13…
Successive Flux Rope Eruptions from δ-sunspots Region of NOAA 12673 and Associated X-class Eruptive Flares on 2017 September 6
Joshi, Bhuwan; Veronig, Astrid M.; Mitra, Prabir K. +2 more
In this article, we present a multiwavelength analysis of two X-class solar eruptive flares of classes X2.2 and X9.3 that occurred in the sigmoidal active region NOAA 12673 on 2017 September 6, by combining observations of Atmospheric Imaging Assembly and Helioseismic Magnetic Imager instruments on board the Solar Dynamics Observatory. On the day …
The Carnegie-Chicago Hubble Program. III. The Distance to NGC 1365 via the Tip of the Red Giant Branch
Madore, Barry F.; Freedman, Wendy L.; Beaton, Rachael L. +8 more
The Carnegie-Chicago Hubble Program (CCHP) seeks to anchor the distance scale of Type Ia supernovae via the Tip of the Red Giant Branch (TRGB) method. Based on deep Hubble Space Telescope ACS/WFC imaging, we present an analysis of the TRGB for the metal-poor halo of NGC 1365, a giant spiral galaxy in the Fornax cluster that was host to the Type Ia…
StarGO: A New Method to Identify the Galactic Origins of Halo Stars
Kang, Xi; Chang, Jiang; Han, Jiaxin +3 more
We develop a new method, Stars’ Galactic Origin (StarGO), to identify the galactic origins of halo stars using their kinematics. Our method is based on a self-organizing map (SOM), which is one of the most popular unsupervised learning algorithms. STARGO combines SOM with a novel adaptive group identification algorithm with essentially no free par…
Galaxy and Quasar Fueling Caught in the Act from the Intragroup to the Interstellar Medium
Bouché, Nicolas; Marino, Raffaella A.; Maseda, Michael V. +11 more
We report the discovery of six spatially extended (10-100 kpc) line-emitting nebulae in the z ≈ 0.57 galaxy group hosting PKS 0405-123, one of the most luminous quasars at z < 1. The discovery is enabled by the Multi Unit Spectroscopic Explorer and provides tantalizing evidence connecting large-scale gas streams with nuclear activity on scales …