Search Publications
Connecting Coronal Mass Ejections to Their Solar Active Region Sources: Combining Results from the HELCATS and FLARECAST Projects
Gallagher, Peter T.; Murray, Sophie A.; Guerra, Jordan A. +5 more
Coronal mass ejections (CMEs) and other solar eruptive phenomena can be physically linked by combining data from a multitude of ground-based and space-based instruments alongside models; however, this can be challenging for automated operational systems. The EU Framework Package 7 HELCATS project provides catalogues of CME observations and propert…
Chemical Abundances in the Leading Arm of the Magellanic Stream
Richter, Philipp; Lockman, Felix J.; Fox, Andrew J. +8 more
The Leading Arm (LA) of the Magellanic Stream is a vast debris field of H I clouds connecting the Milky Way and the Magellanic Clouds. It represents an example of active gas accretion onto the Galaxy. Previously, only one chemical abundance measurement had been made in the LA. Here we present chemical abundance measurements using Hubble Space Tele…
Magnetic Clouds: Solar Cycle Dependence, Sources, and Geomagnetic Impacts
Luhmann, J. G.; Li, Y.; Lynch, B. J.
Magnetic clouds (MCs) are transient magnetic structures giving the strongest southward magnetic field (Bz south) in the solar wind. The sheath regions of MCs may also carry a southward magnetic field. The southward magnetic field is responsible for space-weather disturbances. We report a comprehensive analysis of MCs and Bz components in their she…
Cold electrons at comet 67P/Churyumov-Gerasimenko
Henri, P.; Rubin, M.; Vigren, E. +4 more
Context. The electron temperature of the plasma is one important aspect of the environment. Electrons created by photoionization or impact ionization of atmospheric gas have energies 10 eV. In an active comet coma, the gas density is high enough for rapid cooling of the electron gas to the neutral gas temperature (a few hundred kelvin). How coolin…
Understanding the strong intervening O VI absorber at zabs ∼ 0.93 towards PG1206+459
Wakker, B. P.; Kacprzak, G. G.; Muzahid, S. +3 more
We have obtained new observations of the partial Lyman limit absorber at zabs=0.93 towards quasar PG 1206+459, and revisit its chemical and physical conditions. The absorber, with N({H I})∼ 10^{17.0} cm-2 and absorption lines spread over ≳1000 km s-1 in velocity, is one of the strongest known O VI absorbers at \log…
Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +191 more
We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray/gamma-ray sources on the sky, and the only source from whi…
Solar Eruptions, Forbush Decreases, and Geomagnetic Disturbances From Outstanding Active Region 12673
Chertok, I. M.; Belov, A. V.; Abunin, A. A.
Based on our tool for the early diagnostics of solar eruption geoeffectiveness (EDSEG tool; Chertok et al., 2013, https://doi.org/10.1007/s11207-012-0127-1; 2015, https://doi.org/10.1007/s11207-014-0618-3; 2017,
Discovery of the Most Ultra-Luminous QSO Using GAIA, SkyMapper, and WISE
Wolf, Christian; Schmidt, Brian P.; Bian, Fuyan +5 more
We report the discovery of the ultra-luminous quasi-stellar object SMSS J215728.21-360215.1 with magnitude z = 16.9 and W4 = 7.42 at redshift 4.75. Given absolute magnitudes of M145, AB = -29.3, M300, AB = -30.12, and logLbol/Lbol, ⊙ = 14.84, it is the quasi-stellar object with the highest unlensed UV-op…
A Dust-scattering Halo of 4U 1630-47 Observed with Chandra and Swift: New Constraints on the Source Distance
Maccarone, T. J.; Tomsick, J. A.; Kalemci, E.
We have observed the Galactic black hole transient 4U 1630-47 during the decay of its 2016 outburst with Chandra and Swift to investigate the properties of the dust-scattering halo created by the source. The scattering halo shows a structure that includes a bright ring between 80″ and 240″ surrounding the source, and a continuous distribution beyo…
Gravitationally Unstable Condensations Revealed by ALMA in the TUKH122 Prestellar Core in the Orion A Cloud
Sanhueza, Patricio; Choi, Minho; Tatematsu, Ken'ichi +5 more
We have investigated the TUKH122 prestellar core in the Orion A cloud using ALMA 3 mm dust continuum, N2H+ (J = 1-0), and CH3OH ({J}K={2}K-{1}K) molecular-line observations. Previous studies showed that TUKH122 is likely on the verge of star formation because the turbulence is almos…