Related papers: KH15D: a star eclipsed by a large scale dusty vort…
Several processes can cause the shape of an extrasolar giant planet's shadow, as viewed in transit, to depart from circular. In addition to rotational effects, cloud formation, non-homogenous haze production and movement, and dynamical…
(Abridged) Stars more massive than $20-30M_{\odot}$ are so luminous that the radiation force on the cooler, more opaque outer layers can balance or exceed the force of gravity. These near or super-Eddington outer envelopes represent a long…
We have used the Keck I telescope to resolve at mid-infrared wavelengths the dust emission from HD 56126 (IRAS 07134+1005), a post-Asymptotic Giant Branch carbon star with a detached dust shell. The gross morphology of the image can be…
We show that the disruption of a star by a 10^6 solar mass black hole in a galactic nucleus could under favorable circumstances produce an optically-thick envelope that radiates with a thermal spectrum at the Eddington limit, 10^{44} erg/s,…
Apart from thousands of `regular' exoplanet candidates, Kepler satellite has discovered a few stars exhibiting peculiar eclipse-like events. They are most probably caused by disintegrating bodies transiting in front of the star. However,…
We investigate the dynamics of large dust grains in massive lopsided transition discs via 2D hydrodynamical simulations including both gas and dust. Our simulations adopt a ring-like gas density profile that becomes unstable against the…
Optically-thick envelopes may form following the tidal disruption of a star by a massive black hole. Such envelopes would reprocess hard radiation from accretion close to the black hole into the UV and optical bands producing AGN-luminosity…
A simple model is exhibited in which the remnant density of charged vortons is used to provide candidates for explaining the observed ultra high energy cosmic rays (above $10^{20}$ eV). These vortons would be accelerated in active galaxies…
In order to circumvent the loss of solid material through radial drift towards the central star, the trapping of dust inside persistent vortices in protoplanetary discs has often been suggested as a process that can eventually lead to…
Observed events of ultra-high energy cosmic rays may indicate a hard component for the energy spectrum of their flux, which might have origin in the decay of long-lived vortons presumably condensed in the galactic halo. To be consistent…
In recent years spiral structures have been seen in scattered light observations and signs of vortices in millimeter images of protoplanetary disks, both probably linked with the presence of planets. We present ALMA Band 7 (335 GHz or 0.89…
The origin of high velocity stars observed in the halo of our Galaxy is still unclear. In this work we test the hypothesis, raised by results of recent high precision $N$-body simulations, of strong acceleration of stars belonging to a…
We present observations and models of the dust environment of activated asteroid P/2013 P5 (PANSTARRS). The object displayed a complex morphology during the observations, with the presence of multiple tails. We combined our own…
We have constructed and analysed the secular light curve of BP Tau, a classical T Tauri-type star. Wave-like variations in the average brightness were detected, with an amplitude of $\Delta B\approx 0.2$ and characteristic time-scales of…
A pathway to the formation of planetesimals, and eventually giant planets, may occur in concentrations of dust grains trapped in pressure maxima. Dramatic crescent-shaped dust concentrations have been seen in recent radio images at sub-mm…
We find that dust clouds which eclipse young stars obscure the stellar disc inhomogeneously. In the particular case of CQ Tau, we find isolated optically thick structures with sizes $\lesssim0.6R_*$ and derive the typical $A_{V}$ gradient…
We report infrared spectroscopy of the unusual eclipsing pre-main sequence object KH 15D, obtained using NIRSPEC on Keck II. During eclipse, observations using low spectral resolution (1000) reveal the presence of prominent molecular…
Measurements by dust detectors on interplanetary spacecraft appear to indicate a substantial flux of interstellar particles with masses exceeding 10^{-12}gram. The reported abundance of these massive grains cannot be typical of interstellar…
High-resolution ALMA observations have revealed asymmetric dust crescents in several protoplanetary disks, suggesting efficient dust trapping mechanisms potentially linked to gas vortices. While such features have been associated with…
Optically thin dusty disks around Main Sequence stars consist of debris from catastrophic collisions or from low erosion of long-lived planetesimals. Resolved observations of dusty disks have systematically evidenced asymmetries and annular…