相关论文: Arabia: from craters to stone circles
We summarize here the results, most of which are preliminary, of a number of recent observations of the Crab nebula system with the Chandra X-Ray Observatory. We discuss four different topics: (1) The motion on long (> 1yr) time scales of…
Direct detection of dark matter continues to elude scientists' many attempts to see it interact, and still to this day the only way we know it is there is through observed gravitational effects. The many search experiments are at the point…
Clumped dark matter arises naturally within the framwork of generic cosmological dark matter models. Invoking the existence of dark matter clumps can also solve may unexplained mysteries in astrophysics and geology or geophysics, eg. the…
Jupiter and Saturn have extended, nearly toroidal atmospheres composed of material ejected from their moons or rings. Here we suggest that similar atmospheres must exist around giant extrasolar planets and might be observable in a transit…
We have found a class of circular radio objects in the Evolutionary Map of the Universe Pilot Survey, using the Australian Square Kilometre Array Pathfinder telescope. The objects appear in radio images as circular edge-brightened discs,…
We still do not understand how planets form, or why extra-solar planetary systems are so different from our own solar system. But the last few years have dramatically changed our view of the discs of gas and dust around young stars.…
Helioseismology has discovered a thin layer beneath the solar surface where the rotation rate increases rapidly with depth. The normalized rotational shear in the upper 10 Mm of the layer is constant with latitude. Differential rotation…
The field of Galactic Archaeology aims to understand the origins and evolution of the stellar populations in the Milky Way, as a way to understand galaxy formation and evolution in general. The GALAH (Galactic Archaeology with HERMES)…
The climate of early Mars remains a topic of intense debate. Ancient terrains preserve landscapes consistent with stream channels, lake basins, and possibly even oceans, and thus the presence of liquid water flowing on the Martian surface 4…
A sudden release of high energy cosmic rays at the centre of a wind sustaining a spiral magnetic field produces cavities of low density and low magnetic field along the axis. The trajectories of high energy cosmic rays are focussed onto the…
We present a new statistical approach to analyzing an extremely common archaeological data type -- potsherds -- that infers the structure of cultural relationships across a set of excavations. This method, applied to data from a set of…
From al-Sufi's tenth-century observation of the Andromeda Galaxy as a "little cloud" to contemporary space missions, Islamic astronomy represents a millennium-spanning tradition of innovation and knowledge. This study traces its trajectory…
In spite of much work, the overall spiral structure morphology of the Milky Way remains somewhat uncertain. In the last two decades, accurate distance measurements have provided us with an opportunity to solve this issue. Using the precise…
Stellar occultations provide a powerful tool to explore objects of the outer solar system. The Gaia mission now provides milli-arcsec accuracy on the predictions of these events and makes possible observations that were previously…
Meteor light curves are sometimes known to display flickering: rapid, quasi-periodic variations in brightness. This effect is generally attributed to the rotational modulation of the ablation rate, which is caused by the time-varying cross…
Solar sub-surface fluid topology provides an indirect approach to examine the internal characteristics of active regions (ARs). Earlier studies have revealed the prevalence of strong flows in the interior of ARs having complex magnetic…
Periodic comets of different dynamical groups with orbits at 2 - 5 AU still occasionally active. The observed dust activity of such objects can be connected with processes of water ice sublimation (MBCs) or crystallization of amorphous…
A man-made texture on the desert soil of a county of the Western China is visible in satellite images, more than 8 kilometers long and 50 meters wide. This seems to be the result of a detailed geophysical survey of the region that led to…
The $\delta$-Cancrid meteoroid stream forms four active meteor showers which are observable on the Earth annually during January-February and August-September. The stream's definite parent comet has not been established. We performed a…
Maya Blue is actually one of the best known examples of an organic-inorganic hybrid material. Yet despite 50 years of sustained interest, its microscopic structure and its relation to durability remain open questions. We address the issue…