Search Publications
Boron Abundances Across the “Li-Be Dip” in the Hyades Cluster
Deliyannis, Constantine P.; Somers, Garrett; Pinsonneault, Marc H. +3 more
Dramatic deficiencies of Li in the mid-F dwarf stars of the Hyades cluster were discovered by Boesgaard & Tripicco. Boesgaard & King discovered corresponding, but smaller, deficiencies in Be in the same narrow temperature region in the Hyades. Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we investigate B ab…
A Comparison and Joint Analysis of Sunyaev-Zel’dovich Effect Measurements from Planck and Bolocam for a Set of 47 Massive Galaxy Clusters
Pierpaoli, Elena; Merten, Julian; Sayers, Jack +7 more
We measure the Sunyaev-Zel’dovich (SZ) signal toward a set of 47 clusters with a median mass of 9.5 × 1014 M ⊙ and a median redshift of 0.40 using data from Planck and the ground-based Bolocam receiver. When Planck XMM-like masses are used to set the scale radius {θ }{{s}}, we find consistency between the integrate…
X-Ray and Optical Correlation of Type I Seyfert NGC 3516 Studied with Suzaku and Japanese Ground-based Telescopes
Kawabata, Koji; Fukazawa, Yasushi; Makishima, Kazuo +23 more
From 2013 April to 2014 April, we performed X-ray and optical simultaneous monitoring of the type 1.5 Seyfert galaxy NGC 3516. We employed Suzaku and five Japanese ground-based telescopes—the Pirka, Kiso Schmidt, Nayuta, MITSuME, and the Kanata telescopes. The Suzaku observations were conducted seven times with various intervals ranging from days …
First NuSTAR Observations of the BL Lac-type Blazar PKS 2155-304: Constraints on the Jet Content and Distribution of Radiating Particles
Harrison, F. A.; Hornstrup, A.; Hailey, C. +35 more
We report the first hard X-ray observations with NuSTAR of the BL Lac-type blazar PKS 2155-304, augmented with soft X-ray data from XMM-Newton and γ-ray data from the Fermi Large Area Telescope, obtained in 2013 April when the source was in a very low flux state. A joint NuSTAR and XMM spectrum, covering the energy range 0.5-60 keV, is best descri…
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…
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 …
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…
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…
Reconnection Properties of Large-scale Current Sheets During Coronal Mass Ejection Eruptions
Lynch, B. J.; Guidoni, S. E.; Edmondson, J. K. +1 more
We present a detailed analysis of the properties of magnetic reconnection at large-scale current sheets (CSs) in a high cadence version of the Lynch & Edmondson 2.5D MHD simulation of sympathetic magnetic breakout eruptions from a pseudostreamer source region. We examine the resistive tearing and break-up of the three main CSs into chains of X…