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Hydrogen Balmer Continuum in Solar Flares Detected by the Interface Region Imaging Spectrograph (IRIS)
Heinzel, P.; Kleint, L.
We present a novel observation of the white light flare (WLF) continuum, which was significantly enhanced during the X1 flare on 2014 March 29 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its near-UV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above …
Parallax beyond a Kiloparsec from Spatially Scanning the Wide Field Camera 3 on the Hubble Space Telescope
Casertano, Stefano; Anderson, Jay; Filippenko, Alexei V. +2 more
We use a newly developed observing mode on the Hubble Space Telescope (HST) and Wide Field Camera 3, spatial scanning, to increase source sampling a thousand-fold and measure changes in source positions to a precision of 20-40 µas, more than an order of magnitude better than attainable in pointed observations. This observing mode can usefull…
Jet contributions to the broad-band spectrum of Cyg X-1 in the hard state
Stawarz, Łukasz; Zdziarski, Andrzej A.; Sikora, Marek +1 more
We apply the jet model developed in the preceding paper of Zdziarski et al. to the hard-state emission spectra of Cyg X-1. We augment the model for the analytical treatment of the particle evolution beyond the energy dissipation region, and allow for various forms of the acceleration rate. We calculate the resulting electron and emission spectra a…
VIMOS Ultra-Deep Survey (VUDS): Witnessing the assembly of a massive cluster at z ~ 3.3
Maccagni, D.; Cimatti, A.; Ilbert, O. +46 more
Using new spectroscopic observations obtained as part of the VIMOS Ultra-Deep Survey (VUDS), we performed a systematic search for overdense environments in the early universe (z> 2) and report here on the discovery of Cl J0227-0421, a massive protocluster at z = 3.29. This protocluster is characterized by both the large overdensity of spectrosc…
Hubble Space Telescope Investigation of Main-belt Comet 133P/Elst-Pizarro
Mutchler, Max; Jewitt, David; Agarwal, Jessica +3 more
We report new observations of the prototype main-belt comet (active asteroid) 133P/Elst-Pizarro taken at high angular resolution using the Hubble Space Telescope. The object has three main components: (1) a point-like nucleus; (2) a long, narrow antisolar dust tail; and (3) a short, sunward anti-tail. There is no resolved coma. The nucleus has a m…
The rise and fall of the Type Ib supernova iPTF13bvn. Not a massive Wolf-Rayet star
Cenko, S. B.; Sollerman, J.; Gal-Yam, A. +9 more
Context. We investigate iPTF13bvn, a core-collapse (CC) supernova (SN) in the nearby spiral galaxy NGC 5806. This object was discovered by the intermediate Palomar Transient Factory (iPTF) very close to the estimated explosion date and was classified as a stripped-envelope CC SN, likely of Type Ib. Furthermore, a possible progenitor detection in p…
The kinetic ballooning/interchange instability as a source of dipolarization fronts and auroral streamers
Pritchett, P. L.; Coroniti, F. V.; Nishimura, Y.
The possibility that the dipolarization fronts (DFs) observed in the plasma sheet could be produced by the ballooning/interchange instability is explored using three-dimensional electromagnetic particle-in-cell simulations. The localized interchange heads produced in the nonlinear stage of the instability exhibit the main near-equatorial propertie…
Late-Stage Galaxy Mergers in Cosmos to z ∼ 1
Ilbert, O.; Kartaltepe, J. S.; Jahnke, K. +15 more
The role of major mergers in galaxy and black hole formation is not well-constrained. To help address this, we develop an automated method to identify late-stage galaxy mergers before coalescence of the galactic cores. The resulting sample of mergers is distinct from those obtained using pair-finding and morphological indicators. Our method relies…
Bright flares in supergiant fast X-ray transients
Sidoli, L.; Postnov, K.; Paizis, A. +1 more
At steady low-luminosity states, supergiant fast X-ray transients (SFXTs) can be at the stage of quasi-spherical settling accretion on to slowly rotating magnetized neutron stars from the OB-companion winds. At this stage, a hot quasi-static shell is formed above the magnetosphere, the plasma entry rate into magnetosphere is controlled by (ineffic…
The Broad-band X-Ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation
Harrison, F. A.; Stern, D.; Zhang, W. W. +16 more
We have obtained a deep, simultaneous observation of the bright, nearby Seyfert galaxy IC 4329A with Suzaku and NuSTAR. Through a detailed spectral analysis, we are able to robustly separate the continuum, absorption, and distant reflection components in the spectrum. The absorbing column is found to be modest ({\sim }6 \times 10^{21} {\, cm^{-2}\…