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IRIS, Hinode, SDO, and RHESSI Observations of a White Light Flare Produced Directly by Nonthermal Electrons
Lee, Kyoung-Sun; Brooks, David H.; Watanabe, Kyoko +2 more
An X1.6 flare occurred in active region AR 12192 on 2014 October 22 at 14:02 UT and was observed by Hinode, IRIS, SDO, and RHESSI. We analyze a bright kernel that produces a white light (WL) flare with continuum enhancement and a hard X-ray (HXR) peak. Taking advantage of the spectroscopic observations of IRIS and Hinode/EIS, we measure the tempor…
Gaia's view of the λ Boo star puzzle
Murphy, Simon J.; Paunzen, Ernst
The evolutionary status of the chemically peculiar class of λ Boo stars has been intensely debated. It is now agreed that the λ Boo phenomenon affects A stars of all ages, from star formation to the terminal age main sequence, but the cause of the chemical peculiarity is still a puzzle. We revisit the debate of their ages and temperatures in order…
Narrowing down the possible explanations of cosmic acceleration with geometric probes
Dhawan, Suhail; Goobar, Ariel; Mörtsell, Edvard +2 more
Recent re-calibration of the Type Ia supernova (SNe Ia) magnitude-redshift relation combined with cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) data have provided excellent constraints on the standard cosmological model. Here, we examine particular classes of alternative cosmologies, motivated by various physical mechanis…
Thermonuclear Burst Observations for Model Comparisons: A Reference Sample
Galloway, Duncan K.; Goodwin, Adelle J.; Keek, Laurens
We present observations of thermonuclear (type-I) X-ray bursts, selected for comparison with numerical models. We provide examples of four distinct cases of ignition: He-ignition in mixed H/He fuel (case 1); He-ignition in pure He fuel, following exhaustion of accreted H by steady burning (case 2); ignition in (almost) pure He accumulated from an …
The Eruption of a Small-scale Emerging Flux Rope as the Driver of an M-class Flare and of a Coronal Mass Ejection
Yan, X. L.; Jiang, C. W.; Xue, Z. K. +6 more
Solar flares and coronal mass ejections are the most powerful explosions in the Sun. They are major sources of potentially destructive space weather conditions. However, the possible causes of their initiation remain controversial. Using high-resolution data observed by the New Solar Telescope of Big Bear Solar Observaotry, supplemented by Solar D…
Distinguishing between neutrinos and time-varying dark energy through cosmic time
Calabrese, Erminia; Alonso, David; Lorenz, Christiane S.
We study the correlations between parameters characterizing neutrino physics and the evolution of dark energy. Using a fluid approach, we show that time-varying dark energy models exhibit degeneracies with the cosmic neutrino background over extended periods of the cosmic history, leading to a degraded estimation of the total mass and number of sp…
RefleX: X-ray absorption and reflection in active galactic nuclei for arbitrary geometries
Paltani, S.; Ricci, C.
Reprocessed X-ray radiation carries important information about the structure and physical characteristics of the material surrounding the supermassive black hole (SMBH) in active galactic nuclei (AGN). We report here on a newly developed simulation platform, RefleX, which allows to reproduce absorption and reflection by quasi-arbitrary geometries…
Investigating the X-ray time lags in PG 1244+026 using an extended corona model
Chainakun, P.; Young, A. J.
We present an extended corona model based on ray-tracing simulations to investigate X-ray time lags in active galactic nuclei (AGNs). This model consists of two axial point sources illuminating an accretion disc that produce the reverberation lags. These lags are due to the time delays between the directly observed and reflection photons and are a…
Timescales for the penetration of IMF By into the Earth's magnetotail
Milan, S. E.; Fear, R. C.; Grocott, A. +1 more
Previous studies have shown that there is a correlation between the By component of the interplanetary magnetic field (IMF) and the By component observed in the magnetotail lobe and in the plasma sheet. However, studies of the effect of IMF By on several magnetospheric processes have indicated that the By
Detection of a Large Population of Ultradiffuse Galaxies in Massive Galaxy Clusters: Abell S1063 and Abell 2744
Lee, Myung Gyoon; Lee, Jeong Hwan; Kang, Jisu +1 more
We present the detection of a large population of ultradiffuse galaxies (UDGs) in two massive galaxy clusters, Abell S1063 at z = 0.348 and Abell 2744 at z = 0.308, based on F814W and F105W images in the Hubble Frontier Fields Program. We find 47 and 40 UDGs in Abell S1063 and Abell 2744, respectively. Color-magnitude diagrams of the UDGs show tha…