Search Publications
Empirical model of the Martian dayside ionosphere: Effects of crustal magnetic fields and solar ionizing flux at higher altitudes
Gurnett, D. A.; Němec, F.; Morgan, D. D. +1 more
We use electron density profiles measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument on board the Mars Express spacecraft to investigate the effects of possible controlling parameters unconsidered in the empirical model of Němec et al. (2011, hereafter N11). Specifically, we focus on the effects of crustal magneti…
Formation of new stellar populations from gas accreted by massive young star clusters
Faucher-Giguère, Claude-André; Deng, Licai; de Grijs, Richard +4 more
Stars in clusters are thought to form in a single burst from a common progenitor cloud of molecular gas. However, massive, old ‘globular’ clusters—those with ages greater than ten billion years and masses several hundred thousand times that of the Sun—often harbour multiple stellar populations, indicating that more than one star-forming event occu…
Cold ion heating at the dayside magnetopause during magnetic reconnection
Lavraud, B.; André, M.; Vaivads, A. +5 more
Cold ions of ionospheric origin are known to be present in the magnetospheric side of the Earth's magnetopause. They can be very abundant, with densities up to 100 cm-3. These cold ions can mass load the magnetosphere, changing global parameters of magnetic reconnection, like the Alfvén speed or the reconnection rate. In addition they i…
Local SDSS galaxies in the Herschel Stripe 82 survey: a critical assessment of optically derived star formation rates
Lutz, D.; Trump, J. R.; Mendel, J. T. +2 more
We study a set of 3319 galaxies in the redshift interval 0.04 < z < 0.15 with far-infrared (FIR) coverage from the Herschel Stripe 82 survey (HerS), and emission-line measurements, redshifts, stellar masses and star formation rates (SFRs) from the Sloan Digital Sky Survey (SDSS) (DR7) MPA/JHU data base. About 40 per cent of the sample are de…
Soft γ-ray selected radio galaxies: favouring giant size discovery
Venturi, T.; Dallacasa, D.; Ubertini, P. +5 more
Using the recent INTEGRAL/IBIS and Swift/BAT surveys we have extracted a sample of 64 confirmed plus three candidate radio galaxies selected in the soft gamma-ray band. The sample covers all optical classes and is dominated by objects showing a Fanaroff-Riley type II radio morphology; a large fraction (70 per cent) of the sample is made of `radiat…
In situ observations of flux rope at the separatrix region of magnetic reconnection
Vaivads, A.; Retino, A.; Sahraoui, F. +12 more
We present the first in situ observations of a small-scale flux rope locally formed at the separatrix region of magnetic reconnection without large guide field. Bidirectional electron beams (cold and hot beams) and density cavity accompanied by intense wave activity substantiate the crossing of the separatrix region. Density compression and one pa…
NUSTAR Unveils a Heavily Obscured Low-luminosity Active Galactic Nucleus in the Luminous Infrared Galaxy NGC 6286
Sanders, D. B.; Stern, D.; Treister, E. +8 more
We report the detection of a heavily obscured active galactic nucleus (AGN) in the luminous infrared galaxy (LIRG) NGC 6286 identified in a 17.5 ks Nuclear Spectroscopic Telescope Array observation. The source is in an early merging stage and was targeted as part of our ongoing NuSTAR campaign observing local luminous and ultra-luminous infrared g…
Kinetic Alfvén turbulence below and above ion cyclotron frequency
Wu, D. J.; Zhao, J. S.; Voitenko, Y. M. +1 more
Alfvénic turbulent cascade perpendicular and parallel to the background magnetic field is studied accounting for anisotropic dispersive effects and turbulent intermittency. The perpendicular dispersion and intermittency make the perpendicular-wave-number magnetic spectra steeper and speed up production of high ion cyclotron frequencies by the turb…
Resolving Ionization and Metallicity on Parsec Scales across Mrk 71 with HST-WFC3
Aloisi, Alessandra; James, Bethan L.; Calzetti, Daniela +2 more
Blue compact dwarf (BCD) galaxies in the nearby universe provide a means for studying feedback mechanisms and star formation processes in low-metallicity environments in great detail. Owing to their vicinity, these local analogs to primordial young galaxies are well suited for high-resolution studies that are unfeasible for high-redshift galaxies.…
A model of short-lived outbursts on the 67P from fractured terrains
Keller, H. U.; Hartogh, P.; Rezac, L. +2 more
Aims: We develop a physical model to explain the potent outbursts that occurred in the fractured terrain of comet 67P near perihelion, and predict its temporal characteristics.
Methods: The feasibility of the proposed mechanism is studied using a numerical model accounting for the relevant microscopic/macroscopic processes. We rely on th…