[en] Because there is not enough information to support a rigorous answer, we use a phenomenological approach and conservative assumptions to address the source strength of Jupiter for interplanetary electrons. We estimate that Jupiter emits approximately 10²⁴ - 10²⁶ electrons s^-1 of energy > 6 MeV, which source may be compared with the population of approximately 3 x 10²⁸ electrons of the same energy in Jupiter's outer magnetosphere. We conclude that Jupiter accelerates particles at a rate exceeding that of ordinary trapped particle dynamical processes. (author)

[en] From a re-examination of the trajectories of small charged grains in the vicinity of the Saturnian rings, it is shown that the orbital motion of positively charged grains with a charge-to-mass ratio on the order of 10^–6 e amu^–1 could allow the injection of water material into the equatorial atmosphere. Thus, a mechanism of ionospheric depletion in the equatorial region is provided, as indicated by the Cassini radio occultation measurements.

[en] This work proposes a thermophysical model for realistic surface layers on airless small bodies (RSTPM) for the use of interpreting their multiepoch thermal light curves (e.g., WISE/NEOWISE). RSTPM considers the real orbital cycle, rotation cycle, rough surface, temperature-dependent thermal parameters, as well as contributions of sunlight reflection to observations. It is thus able to produce a precise temperature distribution and thermal emission of airless small bodies regarding the variations on orbital timescales. Details of the physics, mathematics, and numerical algorithms of RSTPM are presented. When used to interpret multiepoch thermal light curves by WISE/NEOWISE, RSTPM can give constraints on the spin orientation and surface physical properties, such as the mean thermal inertia or the mean size of dust grains, the roughness fraction, and the albedo via a radiometric procedure. As an application example, we apply this model to the main-belt object (24) Themis, the largest object of the Themis family, which is believed to be the source region of many main-belt comets. We find multiepoch (2010, 2014–2018) observations of Themis by WISE/NEOWISE, yielding 18 thermal light curves. By fitting these data with RSTPM, the best-fit spin orientation of Themis is derived to be (λ = 137°, β = 59°) in ecliptic coordinates, and the mean radius of dust grains on the surface is estimated to be $\stackrel{~<!--\; ~\; -->}{b}={140}_{-<!--\; ???\; -->114}^{+500}(6\sim <!--\; ???\; -->640)$ μm, indicating that the surface thermal inertia varies from ∼3 Jm⁻² s^−0.5 K⁻¹ to ∼60 Jm⁻² s ^−0.5 K⁻¹ due to seasonal temperature variation. A more detailed analysis found that the thermal light curves of Themis show a weak feature that depends on the rotation phase, which is indicative of heterogeneous thermal properties or imperfections of the light-curve inversion shape model.

[en] The energy and time profiles of 4944 superflares from 77 G-type stars with well-defined light curve periodicities from the Kepler measurements have been analyzed in detail. The total value of the power-law index of the flare frequency distribution as a function of energy (dN/dE ∝ E ^–γ) between 5 × 10³⁴ and 10³⁶ erg is on average γ = 2.04 ± 0.17, which is in agreement with previous results. The γ values of eight stars with frequent flaring activity vary between 1.59 ± 0.06 and 2.11 ± 0.19, suggesting a possible diversity of energy release effects. In general, stars with shorter rotation periods tend to have larger γ values. There is an indication that the flare energy is saturated at about 2 × 10³⁷ erg. For a few large superflares of this energy range, it is found that their temporal behaviors could be characterized by a transition from single impulsive flares to long-duration flares composed of several flares

[en] The NASA Parker Solar Probe and the ESA Solar Orbiter will explore the source region of the solar wind within 20 solar radii. Their unprecedented in-situ measurements are also expected to shed light on the nature of the F-corona and the existence of a halo of nanodust. Such a dust complex might play an important role in the generation of high-speed nanodust grains and the inner-source pickup ions. A brief summary of previous works on this topic is given here to be followed by a sketch on a plan to integrate MHD simulation of solar wind flow dynamics, orbital motion of charged nanodust and the production of energetic neutral atoms (ENAs) in the interplanetary space. (paper)

[en] The Chang'e-3 (CE-3) lander and rover mission to the Moon was an intermediate step in China's lunar exploration program, which will be followed by a sample return mission. The lander was equipped with a number of remote-sensing instruments including a pair of cameras (Landing Camera and Terrain Camera) for recording the landing process and surveying terrain, an extreme ultraviolet camera for monitoring activities in the Earth's plasmasphere, and a first-ever Moon-based ultraviolet telescope for astronomical observations. The Yutu rover successfully carried out close-up observations with the Panoramic Camera, mineralogical investigations with the VIS-NIR Imaging Spectrometer, study of elemental abundances with the Active Particle-induced X-ray Spectrometer, and pioneering measurements of the lunar subsurface with Lunar Penetrating Radar. This special issue provides a collection of key information on the instrumental designs, calibration methods and data processing procedures used by these experiments with a perspective of facilitating further analyses of scientific data from CE-3 in preparation for future missions

[en] We present a detailed description of the interrelation between the Type III radio bursts and energetic phenomena associated with the flare activities in active region AR11158 at 07:58 UT on 2011 February 15. The timing of the Type III radio burst measured by the radio wave experiment on Wind/WAVE and an array of ground-based radio telescopes coincided with an extreme-ultraviolet (EUV) jet and hard X-ray (HXR) emission observed by SDO/AIA and RHESSI, respectively. There is clear evidence that the EUV jet shares the same source region as the HXR emission. The temperature of the jet, as determined by multiwavelength measurements by Atmospheric Imaging Assembly, suggests that Type III emission is associated with hot, 7 MK, plasma at the jet's footpoint.

[en] We investigate the surface thermophysical properties (thermal emissivity, thermal inertia, roughness fraction and geometric albedo) of asteroid (99942) Apophis, using the currently available mid-infrared observations from CanariCam on Gran Telescopio CANARIAS and far-infrared data from PACS on Herschel, based on the Advanced Thermophysical Model. We show that the thermal emissivity of Apophis should be wavelength dependent from 8.70 μm to 160 μm, and the maximum emissivity may appear around 20 μm, similar to that of Vesta. Moreover, we further derive the thermal inertia, roughness fraction, geometric albedo and effective diameter of Apophis within a possible 1$\mathrm{\sigma <!--\; ??\; -->}$ scale of $\mathrm{\Gamma <!--\; ??\; -->}={100}_{-<!--\; ???\; -->52}^{+100}{\mathrm{J}\mathrm{m}}^{-<!--\; ???\; -->2}{\mathrm{s}}^{-<!--\; ???\; -->0.5}{\mathrm{K}}^{-<!--\; ???\; -->1}$, $f_{\mathrm{r}}=0.78\sim <!--\; ???\; -->1.0$, $p_{\mathrm{v}}={0.286}_{-<!--\; ???\; -->0.026}^{+0.030}$ and $D_{\mathrm{e}\mathrm{f}\mathrm{f}}={378}_{-<!--\; ???\; -->25}^{+19}\mathrm{m}$, and 3$\mathrm{\sigma <!--\; ??\; -->}$ scale of $\mathrm{\Gamma <!--\; ??\; -->}={100}_{-<!--\; ???\; -->100}^{+240}{\mathrm{J}\mathrm{m}}^{-<!--\; ???\; -->2}{\mathrm{s}}^{-<!--\; ???\; -->0.5}{\mathrm{K}}^{-<!--\; ???\; -->1}$, $f_{\mathrm{r}}=0.2\sim <!--\; ???\; -->1.0$, $p_{\mathrm{v}}={0.286}_{-<!--\; ???\; -->0.029}^{+0.039}$ and $D_{\mathrm{e}\mathrm{f}\mathrm{f}}={378}_{-<!--\; ???\; -->29}^{+27}\mathrm{m}$. The derived low thermal inertia but high roughness fraction may imply that Apophis could have regolith on its surface, where stronger space weathering but weaker regolith migration has happened in comparison with asteroid Itokawa. Our results show that small-size asteroids could also have fine regolith on the surface, and further infer that Apophis may have been delivered from the Main Belt by the Yarkovsky effect. (paper)

[en] We present the results of a search for high proper motion white dwarfs in the deep survey of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). The CFHTLS Deep Survey covers 4 deg² in five filters (u*, g', r', i', and z'). For the first and the fourth fields, we use data for a 5 year baseline from 2004 to 2009. For the second and the third fields, we have a 4 year baseline from 2004 to 2008. Proper motion selection is used to distinguish cool high-velocity white dwarfs from distant objects with similar blue colors such as compact faint galaxies and quasars. We discovered 44 white dwarf candidates brighter than g' = 24 on the basis of their spectral energy distribution and reduced proper motions. We found one white dwarf candidate with effective temperature less than 4000 K. From its estimated tangential velocity of 31 km s^–1 and a distance of 124 pc, it appears to be located in the thin or thick disk of the Galaxy. We also find five candidates having T_eff between 4000 K and 5000 K. One candidate in D2 with effective temperature of 5000 K and tangential velocity of 190 km s^–1 indicates that it could be in the thick disk or in the halo. The other four candidates are likely located in the thin disk because of their estimated distances and tangential velocity.

[en] We initiated the bilateral collaboration between the Lulin Observatory and the Purple Mountain Observatory to collect asteroid lightcurves using the Chinese Near-Earth Object Survey Telescope at the Xuyi Observation Station. The primary goal of this collaboration was to discover super-fast rotators (SFRs) and study their physical properties. Two campaigns have been conducted: (a) a survey of ∼45 deg² using 8 minute cadence during 2017 February 26–March 2, and (b) a survey of ∼60 deg² using 10 minute cadence during 2018 March 9–12. Our samples are mainly main-belt asteroids and some Hildas and Jupiter Trojans. Out of 4522 collected lightcurves, 506 reliable rotation periods were obtained. Among the reliable rotation periods, we found 16 candidates with a possible rotation period of <2.2 hr, in which (134291) 2006 DZ6 shows a very convincing folded lightcurve and the other 15 candidates only have a likely trend. Further confirmation is needed for the rotation periods of these SFR candidates. In addition, (2280) Kunikov seems to have an eclipsing feature on its lightcurve with a relatively long rotation period suggesting that it is likely a fully synchronized binary asteroid. When the preliminary spin-rate distributions were carried out for asteroids using different sizes, no obvious difference was found.