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Stripped Elliptical Galaxies as Probes of ICM Physics. III. Deep Chandra Observations of NGC 4552: Measuring the Viscosity of the Intracluster Medium
Churazov, E.; Forman, W. R.; Nulsen, P. E. J. +7 more
We present results from a deep (200 ks) Chandra observation of the early-type galaxy NGC 4552 (M89), which is falling into the Virgo cluster. Previous shallower X-ray observations of this galaxy showed a remnant gas core, a tail to the South of the galaxy, and twin “horns” attached to the northern edge of the gas core. In our deeper data, we detec…
The Warm Plasma Composition in the Inner Magnetosphere During 2012-2015
Spence, H. E.; Skoug, R. M.; Goldstein, J. +4 more
Ionospheric heavy ions play an important role in the dynamics of Earth's magnetosphere. The greater mass and gyroradius of ionospheric oxygen differentiates its behavior from protons at the same energies. Oxygen may have an impact on tail reconnection processes, and it can at least temporarily dominate the energy content of the ring current during…
Corotating Magnetic Reconnection Site in Saturn’s Magnetosphere
Lewis, G. R.; Coates, A. J.; Dougherty, M. K. +12 more
Using measurements from the Cassini spacecraft in Saturn’s magnetosphere, we propose a 3D physical picture of a corotating reconnection site, which can only be driven by an internally generated source. Our results demonstrate that the corotating magnetic reconnection can drive an expansion of the current sheet in Saturn’s magnetosphere and, conseq…
The Hubble Space Telescope UV Legacy Survey of Galactic globular clusters - XI. The horizontal branch in NGC 6388 and NGC 6441
Salaris, M.; Di Criscienzo, M.; Anderson, J. +12 more
The Hubble Space Telescope UV Legacy survey of Galactic globular clusters (GC) is characterizing many different aspects of their multiple stellar populations. The `Grundahl-jump' (G-jump) is a discontinuity in ultraviolet brightness of blue horizontal branch (HB) stars, signalling the onset of radiative metal levitation. The HB Legacy data confirm…
Kinematics of Subluminous O and B Stars by Surface Helium Abundance
Jeffery, C. S.; Woolf, V. M.; Martin, P. +1 more
The majority of hot subdwarf stars are low-mass core-helium-burning stars. Their atmospheres are generally helium deficient; however, a minority have extremely helium-rich surfaces. An additional fraction have an intermediate surface-helium abundance, occasionally accompanied by peculiar abundances of other elements. We have identified a sample of…
HST and ground-based spectroscopy of quasar outflows: from mini-BALs to BALs
Shields, J. C.; Hamann, F.; Capellupo, D. M. +3 more
Quasar outflows have been posited as a mechanism to couple supermassive black holes to evolution in their host galaxies. We use multi-epoch spectra from the Hubble Space Telescope (HST) and ground-based observatories to study the outflows in seven quasars that have C IV outflow lines ranging from a classic broad absorption line (BAL) to weaker/nar…
Photometric behaviour of 67P/Churyumov-Gerasimenko and analysis of its pre-perihelion diurnal variations
Mottola, S.; Erard, S.; Capaccioni, F. +14 more
Spectral parameters measured by the Rosetta/VIRTIS imaging spectrometer on the nucleus of comet 67P/Churyumov-Gerasimenko were studied as a function of incidence, emission and phase angles. A statistical analysis was undertaken for a number of spectral parameters: reflectance at seven wavelengths (0.55, 0.75, 1.2, 1.7, 2.0, 2.8 and 4.0 µm), …
Cool and hot emission in a recurring active region jet
Del Zanna, Giulio; Mulay, Sargam M.; Mason, Helen
Aims: We present a thorough investigation of the cool and hot temperature components in four recurring active region jets observed on July 10, 2015 using the Atmospheric Imaging Assembly (AIA), X-ray Telescope (XRT), and Interface Region Imaging Spectrograph (IRIS) instruments.
Methods: A differential emission measure (DEM) analysis was …
HST/WFC3 observations of Uranus' 2014 storm clouds and comparison with VLT/SINFONI and IRTF/Spex observations
Wong, Michael H.; Irwin, Patrick G. J.; Orton, G. S. +2 more
In November 2014 Uranus was observed with the Wide Field Camera 3 (WFC3) instrument of the Hubble Space Telescope as part of the Hubble 2020: Outer Planet Atmospheres Legacy program, OPAL. OPAL annually maps Jupiter, Uranus and Neptune (and will also map Saturn from 2018) in several visible/near-infrared wavelength filters. The Uranus 2014 OPAL ob…
Seasonal Changes in Hydrogen Escape From Mars Through Analysis of HST Observations of the Martian Exosphere Near Perihelion
Villanueva, G. L.; Bertaux, J. L.; Clarke, J. T. +5 more
Hubble Space Telescope (HST) observations of the Martian hydrogen exosphere in Lyman α are presented in this paper for a period when Mars passed perihelion and southern summer solstice in its orbit. The peak intensity in the exospheric Lyman α brightness was recorded after Mars went past its perihelion, slightly after southern summer solstice. The…