Search Publications
The Next Generation Virgo Cluster Survey XVI: The Angular Momentum of Dwarf Early-type Galaxies from Globular Cluster Satellites
Zhang, Hongxin; Emsellem, Eric; Liu, Chengze +10 more
We analyze the kinematics of six Virgo cluster dwarf early-type galaxies (dEs) from their globular cluster (GC) systems. We present new Keck/DEIMOS spectroscopy for three of them and re-analyze the data found in the literature for the remaining three. We use two independent methods to estimate the rotation amplitude (V rot) and velocity…
GRS 1739-278 Observed at Very Low Luminosity with XMM-Newton and NuSTAR
Harrison, F. A.; Stern, D.; Yamaoka, K. +19 more
We present a detailed spectral analysis of XMM-Newton and NuSTAR observations of the accreting transient black hole GRS 1739-278 during a very faint low hard state at ∼0.02% of the Eddington luminosity (for a distance of 8.5 kpc and a mass of 10 {M}⊙ ). The broadband X-ray spectrum between 0.5 and 60 keV can be well-described by a power…
Hubble Space Telescope Observations of Accretion-Induced Star Formation in the Tadpole Galaxy Kiso 5639
Rafelski, Marc; Elmegreen, Bruce G.; Gallagher, John S. +6 more
The tadpole galaxy Kiso 5639 has a slowly rotating disk with a drop in metallicity at its star-forming head, suggesting that star formation was triggered by the accretion of metal-poor gas. We present multi-wavelength Hubble Space Telescope Wide Field Camera 3 images of UV through I band plus Hα to search for peripheral emission and determine the …
The Electron Density in Explosive Transition Region Events Observed by IRIS
Young, P. R.; Doschek, G. A.; Warren, H. P.
We discuss the intensity ratio of the O IV line at 1401.16 Å to the Si IV line at 1402.77 Å in Interface Region Imaging Spectrograph (IRIS) spectra. This intensity ratio is important if it can be used to measure high electron densities that cannot be measured using line intensity ratios of two different O IV lines from the multiplet within the IRI…
Deep Near-IR Observations of the Globular Cluster M4: Hunting for Brown Dwarfs
Knigge, C.; Bedin, L. R.; Rich, R. M. +5 more
We present an analysis of deep Hubble Space Telescope (HST)/Wide Field Camera 3 near-IR (NIR) imaging data of the globular cluster (GC) M4. The best-photometry NIR color-magnitude diagram (CMD) clearly shows the main sequence extending toward the expected end of the hydrogen-burning limit and going beyond this point toward fainter sources. The whi…
A New 3D Multi-fluid Model: A Study of Kinetic Effects and Variations of Physical Conditions in the Cometary Coma
Huang, Z.; Jia, X.; Bieler, A. +8 more
Physics-based numerical coma models are desirable whether to interpret the spacecraft observations of the inner coma or to compare with the ground-based observations of the outer coma. In this work, we develop a multi-neutral-fluid model based on the BATS-R-US code of the University of Michigan, which is capable of computing both the inner and out…
The Molecular Baryon Cycle of M82
Chisholm, John; Matsushita, Satoki
Baryons cycle into galaxies from the intergalactic medium and are converted into stars; a fraction of the baryons are ejected out of galaxies by stellar feedback. Here we present new high-resolution (3.″9 68 pc) 12CO(2-1) and 12CO(3-2) images that probe these three stages of the baryon cycle in the nearby starburst M82. We co…
A Nanoflare-based Cellular Automaton Model and the Observed Properties of the Coronal Plasma
Klimchuk, James A.; López Fuentes, Marcelo
We use the cellular automaton model described in López Fuentes & Klimchuk to study the evolution of coronal loop plasmas. The model, based on the idea of a critical misalignment angle in tangled magnetic fields, produces nanoflares of varying frequency with respect to the plasma cooling time. We compare the results of the model with active reg…
Correlation of Coronal Plasma Properties and Solar Magnetic Field in a Decaying Active Region
Warren, Harry P.; Ugarte-Urra, Ignacio; Young, Peter R. +2 more
We present the analysis of a decaying active region observed by the EUV Imaging Spectrometer on Hinode during 2009 December 7-11. We investigated the temporal evolution of its structure exhibited by plasma at temperatures from 300,000 to 2.8 million degrees, and derived the electron density, differential emission measure, effective electron temper…
The Extreme Ultraviolet Variability of Quasars
O'Dea, Christopher P.; Zhang, Shaohua; Muzahid, Sowgat +2 more
We study the extreme ultraviolet (EUV) variability (rest frame wavelengths 500-920 Å) of high-luminosity quasars using Hubble Space Telescope (HST) (low to intermediate redshift sample) and Sloan Digital sky Survey (SDSS) (high redshift sample) archives. The combined HST and SDSS data indicates a much more pronounced variability when the sampling …