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Diversity of chemistry and excitation conditions in the high-mass star forming complex W33
Immer, K.; Galván-Madrid, R.; König, C. +2 more
The object W33 is a giant molecular cloud that contains star forming regions at various evolutionary stages from quiescent clumps to developed H ii regions. Since its star forming regions are located at the same distance and the primary material of the birth clouds is probably similar, we conducted a comparative chemical study to trace the chemica…
Comparing M31 and Milky Way Satellites: The Extended Star Formation Histories of Andromeda II and Andromeda XVI
Ferguson, Henry C.; McQuinn, Kristen B. W.; Dolphin, Andrew E. +16 more
We present the first comparison between the lifetime star formation histories (SFHs) of M31 and Milky Way (MW) satellites. Using the Advanced Camera for Surveys on board the Hubble Space Telescope, we obtained deep optical imaging of Andromeda II (And II; MV = -12.0 log(M sstarf/M ⊙) ~ 6.7) and Andromeda XVI (And X…
The narrow Fe Kα line and the molecular torus in active galactic nuclei: an IR/X-ray view
Paltani, S.; Gandhi, P.; Stalevski, M. +5 more
The narrow component of the iron Kα is an almost ubiquitous feature in the X-ray spectra of active galactic nuclei (AGN) and is believed to originate in neutral material, possibly located in the molecular torus. This would imply a tight connection between the Fe Kα equivalent width (EW) and the physical properties of the torus. In a recent work we…
Hubble Space Telescope Imaging of Decoupled Dust Clouds in the Ram Pressure Stripped Virgo Spirals NGC 4402 and NGC 4522
Kenney, Jeffrey D. P.; Abramson, Anne
We present the highest-resolution study to date of the interstellar medium (ISM) in galaxies undergoing ram pressure stripping, using Hubble Space Telescope BVI imaging of NGC 4522 and NGC 4402, Virgo Cluster spirals that are well known to be experiencing intracluster medium (ICM) ram pressure. We find that throughout most of both galaxies, the ma…
Detailed modelling of the circumstellar molecular line emission of the S-type AGB star W Aquilae
Olofsson, H.; Justtanont, K.; Lombaert, R. +5 more
Context. S-type AGB stars have a C/O ratio which suggests that they are transition objects between oxygen-rich M-type stars and carbon-rich C-type stars. As such, their circumstellar compositions of gas and dust are thought to be sensitive to their precise C/O ratio, and it is therefore of particular interest to examine their circumstellar propert…
Properties of dust particles near Saturn inferred from voltage pulses induced by dust impacts on Cassini spacecraft
Gurnett, D. A.; Kempf, S.; Kurth, W. S. +5 more
The Cassini Radio and Plasma Wave Science (RPWS) instrument can detect dust particles when voltage pulses induced by the dust impacts are observed in the wideband receiver. The size of the voltage pulse is proportional to the mass of the impacting dust particle. For the first time, the dust impacts signals measured by dipole and monopole electric …
Survey and Merging of Sunspot Catalogs
Clette, Frédéric; Lefevre, Laure
In view of the construction of new sunspot-based activity indices and proxies, we conducted a comprehensive survey of all existing catalogs providing detailed parameters of photospheric features over long time intervals. Although there are a fair number of such catalogs, a global evaluation showed that they suffer from multiple limitations: finite…
Star-cluster Mass and Age Distributions of Two Fields in M83 Based on HST/WFC3 Observations
Calzetti, Daniela; Whitmore, Bradley C.; Chandar, Rupali +1 more
We study star clusters in two fields in the nearby spiral galaxy M83 using broadband and narrowband optical imaging taken with the Wide Field Camera 3 onboard the Hubble Space Telescope. We present results on the basis of several different catalogs of star clusters in inner and outer fields, and we conclude that different methods of selection do n…
Fast transport of resonant electrons in phase space due to nonlinear trapping by whistler waves
Krasnoselskikh, V.; Artemyev, A. V.; Agapitov, O. V. +4 more
We present an analytical, simplified formulation accounting for the fast transport of relativistic electrons in phase space due to wave-particle resonant interactions in the inhomogeneous magnetic field of Earth's radiation belts. We show that the usual description of the evolution of the particle velocity distribution based on the Fokker-Planck e…
Probing spatial homogeneity with LTB models: a detailed discussion
Bartelmann, M.; Lewis, G. F.; Meyer, S. +2 more
Do current observational data confirm the assumptions of the cosmological principle, or is there statistical evidence for deviations from spatial homogeneity on large scales? To address these questions, we developed a flexible framework based on spherically symmetric, but radially inhomogeneous Lemaître-Tolman-Bondi (LTB) models with synchronous B…