Search Publications
The Warm Gas in the MW: A Kinematical Model
Bregman, Joel N.; Qu, Zhijie; Lindley, Ryan +2 more
We develop a kinematical model for the Milky Way Si IV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line-shape sample extracted from the Hubble Space Telescope/Cosmic Origins Spectrograph archival data, which contains 186 active galactic nucleus sight lines. We find that the Si IV …
ZFIRE: Measuring Electron Density with [O II] as a Function of Environment at z = 1.62
Papovich, Casey; Kewley, Lisa J.; Harshan, Anishya +8 more
The global star formation rates (SFR) of galaxies at fixed stellar masses increase with redshift and are known to vary with environment up to z ∼ 2. We explore here whether the changes in the SFRs also apply to the electron densities of the interstellar medium by measuring the [O II] (λ 3726, λ 3729) ratio for cluster and field galaxies at z ∼ 2. …
On the Coronal Temperature in Solar Microflares
Testa, Paola; Reale, Fabio
We present a study of solar imaging and spectral observations of a microflare, focusing on the temperature diagnostics provided by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, and the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board Hinode. Our data analysis, in particular from the emission in the 131 and …
On the Relation between the Hard X-Ray Photon Index and Accretion Rate for Super-Eddington Accreting Quasars
Luo, Bin; Huang, Jian; Du, Pu +3 more
We investigate whether the correlation between the hard X-ray photon index ( ${\rm{\Gamma }}$ ) and accretion rate for super-Eddington accreting quasars is different from that for sub-Eddington accreting quasars. We construct a sample of 113 bright quasars from the Sloan Digital Sky Survey Data Release 14 quasar catalog, with 38 quasars as the sup…
Steady Wind-blown Cavities within Infalling Rotating Envelopes: Application to the Broad Velocity Component in Young Protostars
Johnstone, Doug; Cabrit, Sylvie; Kristensen, Lars E. +1 more
Wind-driven outflows are observed around a broad range of accreting objects throughout the universe, ranging from forming low-mass stars to supermassive black holes. We study the interaction between a central isotropic wind and an infalling, rotating envelope, which determines the steady-state cavity shape formed at their interface under the assum…
A Small-scale Filament Eruption Inducing a Moreton Wave, an EUV Wave, and a Coronal Mass Ejection
Xue, Zhike; Yan, Xiaoli; Wang, Jincheng +3 more
With the launch of the Solar Dynamic Observatory, many extreme ultraviolet (EUV) waves have been observed during solar eruptions. However, joint observations of Moreton and EUV waves are still relatively rare. We present an event in active region NOAA 12740 wherein a small-scale filament eruption simultaneously results in a Moreton wave, an EUV wa…
Statistical Analysis of the Relation between Coronal Mass Ejections and Solar Energetic Particles
Yashiro, Seiji; Nitta, Nariaki V.; Ichimoto, Kiyoshi +4 more
To improve the forecasting capability of impactful solar energetic particle (SEP) events, the relation between coronal mass ejections (CMEs) and SEP events needs to be better understood. Here we present a statistical study of SEP occurrences and timescales with respect to the CME source locations and speeds, considering all 257 fast (vCME
Cloud Atlas: Unraveling the Vertical Cloud Structure with the Time-series Spectrophotometry of an Unusually Red Brown Dwarf
Schneider, Glenn; Apai, Dániel; Marley, Mark +8 more
Rotational modulations of emission spectra in brown dwarf and exoplanet atmospheres show that clouds are often distributed non-uniformly in these ultracool atmospheres. The spatial heterogeneity in cloud distribution demonstrates the impact of atmospheric dynamics on cloud formation and evolution. In this study, we update the Hubble Space Telescop…
Investigation of Coronal Properties of X-Ray Bright G-dwarf Stars Based on the Solar Surface Magnetic Field-Corona Relationship
Takasao, Shinsuke; Mitsuishi, Ikuyuki; Ishihara, Daisuke +4 more
We investigated the coronal properties of G-dwarf stars including the Sun over a wide range of X-ray luminosity LX (3 × 1026 to 2 × 1030 erg s-1). We analyzed the archival data of 10 X-ray bright (LX > 1028 erg s-1) G-dwarf stars to derive their emission measure (EM) a…
Electric Current Evolution at the Footpoints of Solar Eruptions
Barczynski, Krzysztof; Aulanier, Guillaume; Janvier, Miho +2 more
Electric currents play a critical role in the triggering of solar flares and their evolution. The aim of the present paper is to test whether the surface electric current has a surface or subsurface fixed source as predicted by the circuit approach of flare physics, or is the response of the surface magnetic field to the evolution of the coronal m…