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The Spatial and Temporal Variations of Turbulence in a Solar Flare
Kontar, Eduard P.; Jeffrey, Natasha L. S.; Stores, Morgan
Magnetohydrodynamic plasma turbulence is believed to play a vital role in the production of energetic electrons during solar flares, and the nonthermal broadening of spectral lines is a key sign of this turbulence. Here, we determine how flare turbulence evolves in time and space using spectral profiles of Fe XXIV, Fe XXIII, and Fe XVI, observed b…
ν Gem: A Hierarchical Triple System with an Outer Be Star
Gies, Douglas R.; Klement, Robert; Rivinius, Thomas +17 more
Time series of spectroscopic, speckle-interferometric, and optical long-baseline-interferometric observations confirm that ν Gem is a hierarchical triple system. It consists of an inner binary composed of two B-type stars and an outer classical Be star. Several photospheric spectral lines of the inner components were disentangled, revealing two st…
An enquiry on the origins of N-rich stars in the inner Galaxy based on APOGEE chemical compositions
Bizyaev, Dmitry; Brownstein, Joel R.; Pan, Kaike +10 more
Recent evidence based on APOGEE data for stars within a few kpc of the Galactic Centre suggests that dissolved globular clusters (GCs) contribute significantly to the stellar mass budget of the inner halo. In this paper, we enquire into the origins of tracers of GC dissolution, N-rich stars, that are located in the inner 4 kpc of the Milky Way. Fr…
A search for trends in spatially resolved debris discs at far-infrared wavelengths
Marshall, J. P.; Wang, L.; Kennedy, G. M. +2 more
Debris discs around main-sequence stars are belts of planetesimals - asteroids and comets - formed in the protoplanetary discs around young stars. Planetesimals comprise both the building blocks of planets around young stars and the source of dusty debris around older stars. Imaging observations of dust continuum emission and scattered light revea…
Creation/destruction of ultra-wide binaries in tidal streams
Peñarrubia, Jorge
This paper uses statistical and N-body methods to explore a new mechanism to form binary stars with extremely large separations ( ${\gtrsim}0.1\, {\rm pc}$ ), whose origin is poorly understood. Here, ultra-wide binaries arise via chance entrapment of unrelated stars in tidal streams of disrupting clusters. It is shown that (i) the formation of ult…
Detection of Aerosols at Microbar Pressures in an Exoplanet Atmosphere
West, Robert; Swain, Mark R.; Estrela, Raissa +3 more
The formation of hazes at microbar pressures has been explored by theoretical models of exoplanet atmospheres to explain Rayleigh scattering and/or featureless transmission spectra; however observational evidence of aerosols in the low-pressure formation environments has proved elusive. Here, we show direct evidence of aerosols existing at ~1 micr…
First Cospatial Comparison of Stellar, Neutral-gas, and Ionized-gas Metallicities in a Metal-rich Galaxy: M83
Faucher-Giguère, Claude-André; Hafen, Zachary; Kumari, Nimisha +14 more
We carry out a comparative analysis of the metallicities from the stellar, neutral-gas, and ionized-gas components in the metal-rich spiral galaxy M83. We analyze spectroscopic observations taken with the Hubble Space Telescope, the Large Binocular Telescope, and the Very Large Telescope. We detect a clear depletion of the H I gas, as observed fro…
High-resolution Extinction Map in the Direction of the Strongly Obscured Bulge Fossil Fragment Liller 1
Pallanca, Cristina; Dalessandro, Emanuele; Ferraro, Francesco R. +11 more
We used optical images acquired with the Wide Field Camera of the Advanced Camera for Surveys on board the Hubble Space Telescope and near-infrared data from Gemini Multi-conjugate Adaptive Optics System (GeMS)/Gemini South Adaptive Optics Imager (GSAOI) to construct a high-resolution extinction map in the direction of the bulge stellar system Lil…
Solar Energetic Electron Events Associated with Hard X-Ray Flares
Krucker, Säm; Su, Yang; Mason, Glenn M. +3 more
We investigate 16 solar energetic electron (SEE) events measured by WIND/3DP with a double-power-law spectrum and the associated western hard X-ray (HXR) flares measured by RHESSI with good count statistics, from 2002 February to 2016 December. In all the 16 cases, the presence of an SEE power-law spectrum extending down to ≤5 keV at 1 au implies …
Discovery of new globular clusters in the Sagittarius dwarf galaxy
Minniti, D.; Rejkuba, M.; Ripepi, V. +14 more
Context. Globular clusters (GCs) are witnesses of the past accretion events onto the Milky Way. In particular, the GCs of the Sagittarius (Sgr) dwarf galaxy are important probes of an on-going merger.
Aims: Our main goal is to search for new GC members of this dwarf galaxy using the VISTA Variables in the Via Lactea Extended Survey (VVVX) nea…