11,292 research outputs found
Molecular Lines of 13 Galactic Infrared Bubble Regions
We investigated the physical properties of molecular clouds and star
formation processes around infrared bubbles which are essentially expanding HII
regions. We performed observations of 13 galactic infrared bubble fields
containing 18 bubbles. Five molecular lines, 12CO (J=1-0), 13CO (J=1-0),
C18O(J=1-0), HCN (J=1-0), and HCO+ (J=1-0), were observed, and several publicly
available surveys, GLIMPSE, MIPSGAL, ATLASGAL, BGPS, VGPS, MAGPIS, and NVSS,
were used for comparison. We find that these bubbles are generally connected
with molecular clouds, most of which are giant. Several bubble regions display
velocity gradients and broad shifted profiles, which could be due to the
expansion of bubbles. The masses of molecular clouds within bubbles range from
100 to 19,000 solar mass, and their dynamic ages are about 0.3-3.7 Myr, which
takes into account the internal turbulence pressure of surrounding molecular
clouds. Clumps are found in the vicinity of all 18 bubbles, and molecular
clouds near four of these bubbles with larger angular sizes show shell-like
morphologies, indicating that either collect-and-collapse or radiation-driven
implosion processes may have occurred. Due to the contamination of adjacent
molecular clouds, only six bubble regions are appropriate to search for
outflows, and we find that four of them have outflow activities. Three bubbles
display ultra-compact HII regions at their borders, and one of them is probably
responsible for its outflow. In total, only six bubbles show star formation
activities in the vicinity, and we suggest that star formation processes might
have been triggered.Comment: 55 Pages, 32 figures. Accepted for publication in A
Efficient -separability criteria for mixed multipartite quantum states
We investigate classification and detection of entanglement of multipartite
quantum states in a very general setting, and obtain efficient -separability
criteria for mixed multipartite states in arbitrary dimensional quantum
systems. These criteria can be used to distinguish different classes of
multipartite inseparable states and can detect many important multipartite
entangled states such as GHZ states, W states, anti W states, and mixtures
thereof. They detect -nonseparable -partite quantum states which have
previously not been identified. Here . No optimization or
eigenvalue evaluation is needed, and our criteria can be evaluated by simple
computations involving components of the density matrix. Most importantly, they
can be implemented in today's experiments by using at most
local measurements.Comment: 6 pages, 4 figure
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