Search Publications
Suprathermal Electron Strahl Widths in the Presence of Narrow-band Whistler Waves in the Solar Wind
Fazakerley, A. N.; Maksimovic, M.; Alexandrova, O. +2 more
We perform the first statistical study of the effects of the interaction of suprathermal electrons with narrow-band whistler mode waves in the solar wind (SW). We show that this interaction does occur and that it is associated with enhanced widths of the so-called strahl component. The latter is directed along the interplanetary magnetic field awa…
Sun-to-Earth Characteristics of the 2012 July 12 Coronal Mass Ejection and Associated Geo-effectiveness
Möstl, Christian; Wang, Rui; Yang, Zhongwei +2 more
We analyze multi-spacecraft observations associated with the 2012 July 12 coronal mass ejection (CME), covering the source region on the Sun from the Solar Dynamics Observatory, stereoscopic imaging observations from the Solar Terrestrial Relations Observatory (STEREO), magnetic field characteristics from Mercury Surface, Space Environment, Geoche…
Stellar Populations and Star Formation History of the Metal-poor Dwarf Galaxy DDO 68
Cignoni, M.; Tosi, M.; van der Marel, R. P. +6 more
We present the star formation history (SFH) of the extremely metal-poor dwarf galaxy DDO 68, based on our photometry with the Advanced Camera for Surveys. With a metallicity of only 12+{log}({{O}}/{{H}})=7.15 and a very isolated location, DDO 68 is one of the most metal-poor galaxies known. It has been argued that DDO 68 is a young system that sta…
Confirming the Existence of a Quiescent Galaxy Population out to z=3: A Stacking Analysis of Mid-, Far-Infrared and Radio Data
Casey, Caitlin M.; Schinnerer, Eva; Zirm, Andrew W. +15 more
We performed a comprehensive stacking analysis on ∼14,200 quiescent galaxy (QG) candidates at z = 0-3 across mid-, far-infrared (MIR and FIR), and radio wavelengths. Identified via their rest-frame NUV - r and r - J colors, the QG candidates ({M}\star ={10}9.8{{{--}}12.2} {M}⊙ ) have drastically different IR and ra…
The Age, Mass, and Size Distributions of Star Clusters in M51
Schinnerer, Eva; Whitmore, Bradley C.; Chandar, Rupali +4 more
We present a new catalog of 3816 compact star clusters in the grand design spiral galaxy M51 based on observations taken with the Hubble Space Telescope. The age distribution of the clusters declines starting at very young ages, and can be represented by a power law, {dN}/dτ \propto {τ }γ , with γ =-0.65+/- 0.15. No significant changes …
Globular Cluster Systems in Brightest Cluster Galaxies. II. NGC 6166
Whitmore, Bradley C.; Blakeslee, John P.; Rothberg, Barry +3 more
We present new deep photometry of the globular cluster system (GCS) around NGC 6166, the central supergiant galaxy in Abell 2199. Hubble Space Telescope data from the Advanced Camera for Surveys and WFC3 cameras in F475W and F814W are used to determine the spatial distribution of the GCS, its metallicity distribution function (MDF), and the depend…
Flare vs. Shock Acceleration of High-energy Protons in Solar Energetic Particle Events
Cliver, E. W.
Recent studies have presented evidence for a significant to dominant role for a flare-resident acceleration process for high-energy protons in large (“gradual”) solar energetic particle (SEP) events, contrary to the more generally held view that such protons are primarily accelerated at shock waves driven by coronal mass ejections (CMEs). The new …
The Detection of a Hot Molecular Core in the Large Magellanic Cloud with ALMA
Onaka, Takashi; Aikawa, Yuri; Shimonishi, Takashi +1 more
We report the first detection of a hot molecular core outside our Galaxy based on radio observations with ALMA toward a high-mass young stellar object (YSO) in a nearby low metallicity galaxy, the Large Magellanic Cloud (LMC). Molecular emission lines of CO, C17O, HCO+, H13CO+, H2CO, NO, SiO, …
Observational Signatures of Coronal Loop Heating and Cooling Driven by Footpoint Shuffling
Velli, M.; Warren, H. P.; Ugarte-Urra, I. +4 more
The evolution of a coronal loop is studied by means of numerical simulations of the fully compressible three-dimensional magnetohydrodynamic equations using the HYPERION code. The footpoints of the loop magnetic field are advected by random motions. As a consequence, the magnetic field in the loop is energized and develops turbulent nonlinear dyna…
NuSTAR and XMM-Newton Observations of the Hard X-Ray Spectrum of Centaurus A
Harrison, F. A.; Stern, D.; Farrah, D. +28 more
We present simultaneous XMM-Newton and Nuclear Spectroscopic Telescope Array (NuSTAR) observations spanning 3-78 keV of the nearest radio galaxy, Centaurus A (Cen A). The accretion geometry around the central engine in Cen A is still debated, and we investigate possible configurations using detailed X-ray spectral modeling. NuSTAR imaged the centr…