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High Spatial Resolution Fe XII Observations of Solar Active Regions
Testa, Paola; De Pontieu, Bart; Hansteen, Viggo
We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal Fe xii 1349.4 Å emission at unprecedented high spatial resolution (∼0.33″). We find that by using appropriate observational strategies (I.e., long exposures, lossless compression), Fe xii emission can…
An enhanced merger fraction within the galaxy population of the SSA22 protocluster at z = 3.1
Lehmer, B. D.; Alexander, D. M.; Matsuda, Y. +3 more
The overdense environments of protoclusters of galaxies in the early Universe (z > 2) are expected to accelerate the evolution of galaxies, with an increased rate of stellar mass assembly and black hole accretion compared to co-eval galaxies in the average density `field'. These galaxies are destined to form the passive population of massive ga…
The Lyman alpha reference sample. VII. Spatially resolved Hα kinematics
Verhamme, Anne; Cannon, John M.; Hayes, Matthew +19 more
We present integral field spectroscopic observations with the Potsdam Multi-Aperture Spectrophotometer of all 14 galaxies in the z ~ 0.1 Lyman Alpha Reference Sample (LARS). We produce 2D line-of-sight velocity maps and velocity dispersion maps from the Balmer α (Hα) emission in our data cubes. These maps trace the spectral and spatial properties …
O VI Emission Imaging of a Galaxy with the Hubble Space Telescope: a Warm Gas Halo Surrounding the Intense Starburst SDSS J115630.63+500822.1
Scarlata, Claudia; Hayes, Matthew; Östlin, Göran +3 more
We report results from a new Hubble Space Telescope campaign that targets the O VI λ λ 1032,1038 Å doublet in emission around intensely star-forming galaxies. The program aims to characterize the energy balance in starburst galaxies and gas cooling in the difficult-to-map coronal temperature regime of 2{--}5× {10}5 K. We present the fir…
He II λ4686 Emission from the Massive Binary System in η Car: Constraints to the Orbital Elements and the Nature of the Periodic Minima
Gull, T. R.; Corcoran, M. F.; Madura, T. I. +27 more
Eta Carinae (η Car) is an extremely massive binary system in which rapid spectrum variations occur near periastron. Most notably, near periastron the He II λ4686 line increases rapidly in strength, drops to a minimum value, then increases briefly before fading away. To understand this behavior, we conducted an intense spectroscopic monitoring of t…
The X-ray spectral evolution of the ultraluminous X-ray source Holmberg IX X-1
Done, Chris; Roberts, Timothy P.; Luangtip, Wasutep
We present a new analysis of X-ray spectra of the archetypal ultraluminous X-ray source (ULX) Holmberg IX X-1 obtained by the Swift, XMM-Newton and NuSTAR observatories. This ULX is a persistent source, with a typical luminosity of ∼1040 erg s-1, that varied by a factor of 4-5 over eight years. We find that its spectra tend t…
The Solar Internetwork. II. Flux Appearance and Disappearance Rates
Gošić, M.; Bellot Rubio, L. R.; Katsukawa, Y. +2 more
Small-scale internetwork magnetic fields are important ingredients of the quiet Sun. In this paper we analyze how they appear and disappear on the solar surface. Using high resolution Hinode magnetograms, we follow the evolution of individual magnetic elements in the interior of two supergranular cells at the disk center. From up to 38 hr of conti…
The origin of UV-optical variability in AGN and test of disc models: XMM-Newton and ground-based observations of NGC 4395
Gandhi, P.; Netzer, H.; Peterson, B. M. +12 more
The origin of short timescale (weeks/months) variability of AGN, whether due to intrinsic disc variations or reprocessing of X-ray emission by a surrounding accretion disc, has been a puzzle for many years. However recently a number of observational programmes, particularly of NGC 5548 with Swift, have shown that the UV/optical variations lag behi…
Detailed homogeneous abundance studies of 14 Galactic s-process enriched post-AGB stars: In search of lead (Pb)
Van Winckel, H.; Kamath, D.; Karakas, A. I. +4 more
Context. This paper is part of a larger project in which we systematically study the chemical abundances of Galactic and extragalactic post-asymptotic giant branch (post-AGB) stars. The goal at large is to provide improved observational constraints to the models of the complex interplay between the AGB s-process nucleosynthesis and the associated …
Radial Profile of the 3.5 keV Line Out to R200 in the Perseus Cluster
Boyarsky, Alexey; Ruchayskiy, Oleg; Bulbul, Esra +10 more
The recent discovery of the unidentified emission line at 3.5 keV in galaxies and clusters has attracted great interest from the community. As the origin of the line remains uncertain, we study the surface brightness distribution of the line in the Perseus cluster since that information can be used to identify its origin. We examine the flux distr…