Search Publications
HST/WFC3 Observations of an Off-nuclear Superbubble in Arp 220
Kewley, Lisa J.; Lu, Jessica R.; Heckman, Timothy M. +9 more
We present a high spatial resolution optical and infrared study of the circumnuclear region in Arp 220, a late-stage galaxy merger. Narrowband imaging using Hubble Space Telescope/WFC3 has resolved the previously observed peak in Hα+[N ii] emission into a bubble-shaped feature. This feature measures 1.″6 in diameter, or 600 pc, and is only 1″ nort…
Tracing the Metal-poor M31 Stellar Halo with Blue Horizontal Branch Stars
Bell, Eric F.; Williams, Benjamin F.; Gilbert, Karoline M. +8 more
We have analyzed new Hubble Space Telescope (HST)/Advanced Camera for Surveys and HST/WFC3 imaging in F475W and F814W of two previously unobserved fields along the M31 minor axis to confirm our previous constraints on the shape of M31's inner stellar halo. Both of these new data sets reach a depth of at least F814W <27 and clearly detect the bl…
HST/STIS Ultraviolet Spectroscopy of the Components of the Massive Triple Star δ Ori A
Corcoran, Michael F.; Gies, Douglas R.; Moffat, Anthony F. J. +4 more
The multiple star system of δ Orionis is one of the closest examples of a system containing a luminous O-type, bright giant star (component Aa1). It is often used as a spectral-type standard and has the highest observed X-ray flux of any hot-star binary. The main component Aa1 is orbited by two lower mass stars, faint Aa2 in a 5.7 day eclipsing bi…
Are the Bulk of z > 2 Herschel Galaxies Proto-Spheroids?
Pozzi, F.; Gruppioni, C.; Cresci, G. +6 more
We present a backward approach for the interpretation of the evolution of the near-IR and the far-IR luminosity functions (LFs) across the redshift range 0\lt z\lt 3. In our method, late-type galaxies are treated by means of a parametric phenomenological method based on PEP/HerMES data up to z ∼ 4, whereas spheroids are described by means of a phy…
Latitudinal and Energy Dependence of Energetic Neutral Atom Spectral Indices Measured by the Interstellar Boundary Explorer
McComas, D. J.; Fuselier, S. A.; Schwadron, N. A. +8 more
We investigate the latitudinal and energy dependence of the globally distributed 0.5-6 keV energetic neutral atom (ENA) spectra measured by the Interstellar Boundary Explorer (IBEX) during the first 3 yrs of the mission. Our results are: (1) the ENA spectral indices at the two lowest energies (0.89 and 1.47 keV) exhibit no clear trend with eclipti…
Energetic Particle Pressure at Interplanetary Shocks: STEREO-A Observations
Lario, D.; Roelof, E. C.; Decker, R. B. +1 more
We study periods of elevated energetic particle intensities observed by STEREO-A when the partial pressure exerted by energetic (≥83 keV) protons (PEP) is larger than the pressure exerted by the interplanetary magnetic field (PB). In the majority of cases, these periods are associated with the passage of interplanetary shocks…
Dust and Polycyclic Aromatic Hydrocarbon in the HD 34700 Debris Disk
Seok, Ji Yeon; Li, Aigen
The debris disk around the Vega-type star HD 34700 is detected in dust thermal emission from the near-infrared (IR) to millimeter (mm) and submm wavelength range. Also detected is a distinct set of emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 µ {{m}}, which are commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules…
Extinction and Nebular Line Properties of a Herschel-selected Lensed Dusty Starburst at z = 1.027
Ivison, R. J.; Baes, Maarten; Fu, Hai +17 more
We present Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging and grism spectroscopy observations of the Herschel-selected gravitationally lensed starburst galaxy HATLASJ1429-0028. The lensing system consists of an edge-on foreground disk galaxy at z = 0.218 with a nearly complete Einstein ring of the infrared luminous galaxy at z = 1.027. …
Statistics of the Velocity Gradient Tensor in Space Plasma Turbulent Flows
Consolini, Giuseppe; Materassi, Massimo; Federica Marcucci, Maria +1 more
In the last decade, significant advances have been presented for the theoretical characterization and experimental techniques used to measure and model all of the components of the velocity gradient tensor in the framework of fluid turbulence. Here, we attempt the evaluation of the small-scale velocity gradient tensor for a case study of space pla…
2D MHD and 1D HD Models of a Solar Flare—a Comprehensive Comparison of the Results
Srivastava, A. K.; Murawski, K.; Falewicz, R. +1 more
Without any doubt, solar flaring loops possess a multithread internal structure that is poorly resolved, and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause fundamental problems in numerical modeling of flaring loops, such as selection of a structure and a number of thre…