Search Publications
Quasi-periodic Fluctuations and Chromospheric Evaporation in a Solar Flare Ribbon Observed by Hinode/EIS, IRIS, and RHESSI
Brosius, Jeffrey W.; Inglis, Andrew R.; Daw, Adrian N.
The Hinode/Extreme-ultraviolet Imaging Spectrometer (EIS) obtained rapid cadence (11.2 s) EUV stare spectra of an M7.3 flare ribbon in AR 12036 on 2014 April 18. Quasi-periodic (P ≈ 75.6 ± 9.2 s) intensity fluctuations occurred in emission lines of O IV, Mg VI, Mg vii, Si vii, Fe xiv, and Fe xvi during the flare's impulsive rise, and ended when th…
The Dynamical Generation of Current Sheets in Astrophysical Plasma Turbulence
Howes, Gregory G.
Turbulence profoundly affects particle transport and plasma heating in many astrophysical plasma environments, from galaxy clusters to the solar corona and solar wind to Earth's magnetosphere. Both fluid and kinetic simulations of plasma turbulence ubiquitously generate coherent structures, in the form of current sheets, at small scales, and the l…
Is the escape velocity in star clusters linked to extended star formation histories? Using NGC 7252: W3 as a test case
Rejkuba, M.; Cabrera-Ziri, I.; Bastian, N. +9 more
The colour-magnitude diagrams of some intermediate-age (1-2 Gyr) star clusters show unexpectedly broad main-sequence turnoffs, raising the possibility that these clusters have experienced more than one episode of star formation. Such a scenario predicts the existence of an extended main-sequence turnoff (eMSTO) only in clusters with escape velocit…
Neptune's Dynamic Atmosphere from Kepler K2 Observations: Implications for Brown Dwarf Light Curve Analyses
Fortney, Jonathan J.; Wong, Michael H.; Morales-Juberias, Raul +9 more
Observations of Neptune with the Kepler Space Telescope yield a 49 day light curve with 98% coverage at a 1 minute cadence. A significant signature in the light curve comes from discrete cloud features. We compare results extracted from the light curve data with contemporaneous disk-resolved imaging of Neptune from the Keck 10-m telescope at 1.65 …
Herschel Observations of Major Merger Pairs at z = 0: Dust Mass and Star Formation
Yun, Min S.; Gao, Yu; Lu, Nanyao +13 more
We present Herschel PACS and SPIRE far-infrared (FIR) and submillimeter imaging observations for a large K-band selected sample of 88 close major-merger pairs of galaxies (H-KPAIRs) in 6 photometric bands (70, 100, 160, 250, 350, and 500 µm). Among 132 spiral galaxies in the 44 spiral-spiral (S+S) pairs and 44 spiral-elliptical (S+E) pairs, …
Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. IV. Kinematic Profiles and Average Masses of Blue Straggler Stars
Anderson, J.; van der Marel, R. P.; Bellini, A. +3 more
We make use of the Hubble Space Telescope proper-motion catalogs derived by Bellini et al. to produce the first radial velocity dispersion profiles σ (R) for blue straggler stars (BSSs) in Galactic globular clusters (GCs), as well as the first dynamical estimates for the average mass of the entire BSS population. We show that BSSs typically have l…
Dark radiation and inflationary freedom after Planck 2015
Di Valentino, Eleonora; Mena, Olga; Gariazzo, Stefano +2 more
The simplest inflationary models predict a primordial power spectrum (PPS) of the curvature fluctuations that can be described by a power-law function that is nearly scale invariant. It has been shown, however, that the low-multipole spectrum of the cosmic microwave background anisotropies may hint at the presence of some features in the shape of …
Evidence for the Rapid Formation of Low-mass Early-type Galaxies in Dense Environments
Jordán, Andrés; Côté, Patrick; Peng, Eric W. +6 more
We explore the environmental dependence of star formation timescales in low-mass galaxies using the [α/Fe] abundance ratio as an evolutionary clock. We present integrated [α/Fe] measurements for 11 low-mass ({M}\star ∼ {10}9 {M}⊙ ) early-type galaxies (ETGs) with a large range of cluster-centric distance in the Vir…
Ultraviolet diversity of Type Ia Supernovae
Fox, O. D.; Kirshner, R. P.; Foley, Ryan J. +9 more
Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blu…
Cyclic variations in O-C diagrams of field RR Lyrae stars as a result of LiTE
Zejda, M.; Skarka, M.; Liška, J. +2 more
This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for 11 RRab type stars with suspicious behaviour from the GEOS data base, and determined maxima timings from data of sky surveys and our own observations. T…