916 research outputs found
An effective many-body theory for strongly interacting polar molecules
We derive a general effective many-body theory for bosonic polar molecules in
strong interaction regime, which cannot be correctly described by previous
theories within the first Born approximation. The effective Hamiltonian has
additional interaction terms, which surprisingly reduces the anisotropic
features of dipolar interaction near the shape resonance regime. In the 2D
system with dipole moment perpendicular to the plane, we find that the phonon
dispersion scales as \sqrt{|\bfp|} in the low momentum (\bfp) limit,
showing the same low energy properties as a 2D charged Bose gas with Coulomb
() interactions.Comment: Same as published version (11 pages, 2 figure
Early Science with the Large Millimetre Telescope: Molecules in the Extreme Outflow of a proto-Planetary Nebula
Extremely high velocity emission likely related to jets is known to occur in
some proto-Planetary Nebulae. However, the molecular complexity of this
kinematic component is largely unknown. We observed the known extreme outflow
from the proto-Planetary Nebula IRAS 16342-3814, a prototype water fountain, in
the full frequency range from 73 to 111 GHz with the RSR receiver on the Large
Millimetre Telescope. We detected the molecules SiO, HCN, SO, and CO.
All molecular transitions, with the exception of the latter are detected for
the first time in this source, and all present emission with velocities up to a
few hundred km s. IRAS 16342-3814 is therefore the only source of this
kind presenting extreme outflow activity simultaneously in all these molecules,
with SO and SiO emission showing the highest velocities found of these species
in proto-Planetary Nebulae. To be confirmed is a tentative weak SO component
with a FWHM 700 km s. The extreme outflow gas consists of dense
gas (n 10--10 cm), with a mass larger than
0.02--0.15 M. The relatively high abundances of SiO and SO may
be an indication of an oxygen-rich extreme high velocity gas.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Society Letter
LMT/AzTEC observations of Vega
Vega is the prototypical debris disc system. Its architecture has been extensively studied at optical to millimetre wavelengths, revealing a near face-on, broad, and smooth disc with multiple distinct components. Recent millimetre-wavelength observations from ALMA spatially resolved the inner edge of the outer, cold planetesimal belt from the star for the first time. Here we present early science imaging observations of the Vega system with the AzTEC instrument on the 32-m LMT, tracing extended emission from the disc out to 150 au from the star. We compare the observations to three models of the planetesimal belt architecture to better determine the profile of the outer belt. A comparison of these potential architectures for the disc does not significantly differentiate between them with the modelling results being similar in many respects to the previous ALMA analysis, but differing in the slope of the outer region of the disc. The measured flux densities are consistent between the LMT (single dish) and ALMA (interferometric) observations after accounting for the differences in wavelength of observation. The LMT observations suggest the outer slope of the planetesimal belt is steeper than was suggested in the ALMA analysis. This would be consistent with the interferometric observations being mostly blind to structure at the disc outer edges, but the overall low signal to noise of the LMT observations does not definitively resolve the structure of the outer planetesimal belt.FK and JPM acknowledge research support by the Ministry of Science and Technology of Taiwan under grant MOST107-2119-M-001-031-MY3, and Academia Sinica under grant AS-IA-106-M03. JPM acknowledges research support by the Ministry of Science and Technology of Taiwan under grant MOST109-2112-M-001-036-MY3. MC thanks Consejo Nacional de Ciencia y Tecnología (CONACyT) for financial support through grant CB-2015-256961
Probing the origin of cosmic-rays with extremely high energy neutrinos using the IceCube Observatory
A Population‐Based Twin Study on Sleep Duration and Body Composition
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93648/1/oby.2011.274.pd
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