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Estimating the Height of CMEs Associated with a Major SEP Event at the Onset of the Metric Type II Radio Burst during Solar Cycles 23 and 24
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +2 more
We studied the coronal mass ejection (CME) height at the onset of 59 metric type II radio bursts associated with major solar energetic particle (SEP) events, excluding ground level enhancements (GLEs), during solar cycles 23 and 24. We calculated CME heights using a simple flare-onset method used by Gopalswamy et al. to estimate CME heights at the…
Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field
Verscharen, Daniel; Hollweg, Joseph V.; Bourouaine, Sofiane +1 more
Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for limiting differential flow between alpha particles and protons: plasma instabilities and the rotational force. Bot…
Variable Reddening and Broad Absorption Lines in the Narrow-line Seyfert 1 Galaxy WPVS 007: An Origin in the Torus
Komossa, S.; Terndrup, Donald M.; Leighly, Karen M. +2 more
We report the discovery of an occultation event in the low-luminosity narrow-line Seyfert 1 galaxy WPVS 007 in 2015 February and March. In concert with longer timescale variability, these observations place strong constraints on the nature and location of the absorbing material. Swift monitoring has revealed a secular decrease since ∼2010 accompan…
Correcting for Interplanetary Scattering in Velocity Dispersion analysis of Solar Energetic Particles
Laitinen, T.; Valtonen, E.; Dalla, S. +1 more
To understand the origin of Solar Energetic Particles (SEPs), we must study their injection time relative to other solar eruption manifestations. Traditionally the injection time is determined using the Velocity Dispersion Analysis (VDA) where a linear fit of the observed event onset times at 1 AU to the inverse velocities of SEPs is used to deriv…
Rheological and petrological implications for a stagnant lid regime on Venus
Ghail, Richard
Venus is physically similar to Earth but with no oceans and a hot dense atmosphere. Its near-random distribution of impact craters led to the inferences of episodic global resurfacing and a stagnant lid regime, and imply that it is not currently able to lose proportionately as much heat as Earth. This paper shows that a CO2-induced asth…
New constraints on the dust surrounding HR 4796A
Pinte, C.; Augereau, J. -C.; Mawet, D. +7 more
Context. HR 4796A is surrounded by a well-structured and very bright circumstellar disc shaped like an annulus with many interesting features: very sharp inner and outer edges, brightness asymmetries, centre offset, and suspected distortions in the ring.
Aims: We aim to constrain the properties of the dust surrounding the star HR 4796A, in pa…
Disorder in the early universe
Green, Daniel
Little is known about the microscopic physics that gave rise to inflation in our universe. There are many reasons to wonder if the underlying description requires a careful arrangement of ingredients or if inflation was the result of an essentially random process. At a technical level, randomness in the microphysics of inflation is closely related…
Mars Express measurements of surface albedo changes over 2004-2010
Altieri, F.; Vincendon, M.; Audouard, J. +1 more
The pervasive Mars dust is continually transported between the surface and the atmosphere. When on the surface, dust increases the albedo of darker underlying rocks and regolith, which modifies climate energy balance and must be quantified. Remote observation of surface albedo absolute value and albedo change is however complicated by dust itself …
Pre-explosion Companion Stars in Type Iax Supernovae
Wang, B.; Liu, Zheng-Wei; Stancliffe, Richard J. +1 more
Type Iax supernovae (SNe Iax) are proposed as one new sub-class of SNe Ia since they present observational properties that are sufficiently distinct from the bulk of SNe Ia. SNe Iax are the most common of all types of peculiar SNe by both number and rate, with an estimated rate of occurrence of about 5%-30% of the total SN Ia rate. However, the pr…
Deep alteration between Hellas and Isidis Basins
Quantin-Nataf, C.; Bultel, B.; Andréani, M. +2 more
Recent investigations of alteration of martian crustal outcrops suggest putative crustal hydrothermal systems, which are favorable environments for the emergence of life. In this study, we perform an analysis of the CRISM targeted observations covering crustal outcrops in the region between the Hellas and Isidis basins with the goal of investigati…