84,385 research outputs found
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The area around the Orion Nebula observed in the CO (J = 1- 0) transition
An area 1 deg2 around the Orion Nebula has been surveyed with a 2.6 km s-1 wide single-channel receiver. The map shows considerable structure in the east including a bright spot 24' (2.8 pc) from the main CO peak
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CO J = 3→2 and J = 2→1 mapping and spectroscopy of NGC 7027
We present spectra and mapping for NGC 7072 in the J = 3→2 and J = 2→1 transitions of CO. The central profile at J = 2→1 is shown to be very similar to the J = 1→0 spectrum measured by Thronson (1983), and this implies a source expansion at roughly constant velocity. The J = 3→2 line however appears weaker, with evidence for appreciable quenching of the higher velocity components. Detailed modelling f the source indicates that densities n must vary appreciably with shell radius R(as nα R-a, where α≥2), and this leads to a corresponding steep radial decrease in the radiation temperature TR. In consequence, the source FWHM is found to decrease appreciably iwth increasing transition frequency, a trend which appears also to be confirmed by our central J = 3→2 scans. It is not however possible to constrain gas kinetic tempertures TK, the level of CO thermalisation, or shell mass M with any degree of confidence - both low and high mass models appear capable of replicating our spectra.
Finally, the J = 2→1 spatial velocity map displays evidence for a decrease in velocity width towards the outer regions of the nebula; a feature which is expected of most outflow models. The J = 3→2 map also indicates the presence of a nebular extension to the north-west of the peak emission core, although this is not reproduced in the corresponding J = 1→0 map of Mufson et al. (1975)
GENIE observations of small scale astrophysical processes in star forming regions and quasars
The VLTI/GENIE configuration will operate using at least 4 of the VLTI
telescopes (and possibly with one or more of the AT telescopes in the future if
adaptive optics become available on them). GENIE effectively can be thought of
as a 'smart' coronagraph, enabling high dynamic range imaging to be achieved at
moderate spatial resolution, with high rejection of the emission of a central
bright point source. However, but this bright source rejection may only provide
a rather moderate image quality (due to the few baselines and transfer function
on the sky). Operated in this way, only limited image reconstruction is
possible since classical radio and millimeter wavelength interferometry
techniques are not directly applicable to the outputs of optical
interferometers because the absolute phases are generally not measured.
However, measurements of visibility and closure phase could lead to situations
where image reconstruction becomes possible. This paper addresses the issue of
whether there are areas outside of the exoplanet search where it might be able
to make a useful impact on astronomy.Comment: Proceedings of the Genie-Darwin Workshop - Hunting for Planet
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High resolution CO observations of S88-B
CO J = 2-1 and 13CO J = 2-1 and 1-0 observations have been made of the H II region S88-B, using the 15-m James Clerk Maxwell telescope in Hawaii and the 20-m telescope at Onsala. The core of the cloud is resolved into a horseshoelike structure which surrounds a diffuse reflection nebula. The central core has a mass of ≥ 1000 M⊙, with 400 M⊙ in the horseshoe structure. The gas in the horse in the horseshoe appears highly fragmented, and has a kinetic temperature of ≈ 60 K, suggesting it is closely coupled to the dust temperature. A recently formed high mass star appears to be in the process of evacuating a cavity, possibly through a large molecular outflow that is found to show an accelerated component in its blue-shifted lobe. A velocity gradient across the horseshoe structure suggest ordered motion, and could represent rotation in the parental cloud
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High signal/noise <sup>13</sup>CO observations of the bipolar outflow in L1551
New high-signal/noise 13CO observations of the bipolar outflow in the molecular cloud L1551 are reported. Contrary to earlier observations of CO J = 1-0 and 2-1, no strong spatial dependence is found for the velocity profile of these spectra. The implications of these observations are such that the model of an empty shell for this source is less likely, and a model consisting of a shell which contains significant amounts of outflowing molecular gas inside the swept-up cavity walls is suggested
A simplified PERT system
Modified PERT technique processes the input data and arranges it in familiar graphic form in a booklet which is issued at periodic intervals. The tabulated data provides readily available information to management personnel concerned with monitoring the progress of a program
Linear Optical CNOT Gate in the Coincidence Basis
We describe the operation and tolerances of a non-deterministic, coincidence
basis, quantum CNOT gate for photonic qubits. It is constructed solely from
linear optical elements and requires only a two-photon source for its
demonstration.Comment: Submitted to Physical Review
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CCH <i>N</i> = 4-3 emission from dense interstellar clouds
The authors have searched for N = 4 - 3 rotational line emission from the ethynyl radical CCH, at 349 GHz toward a number of galactic molecular clouds. They have detected emission from ten giant molecular clouds and have derived CCH column densities on the order of 1014 - 1015cm-2. They find that CCH emission arises from dense gas, n(H2) ~ 104 - 105cm-3, but not from very dense material, n(H2) > 106cm-3, nor from hot gas such as the "hot core" region in Orion
Hiding Ignorance Using High Dimensions
The absence of information -- entirely or partly -- is called ignorance.
Naturally, one might ask if some ignorance of a whole system will imply some
ignorance of its parts. Our classical intuition tells us yes, however quantum
theory tells us no: it is possible to encode information in a quantum system so
that despite some ignorance of the whole, it is impossible to identify the
unknown part arXiv:1011.6448. Experimentally verifying this counter-intuitive
fact requires controlling and measuring quantum systems of high dimension . We provide this experimental evidence using the transverse spatial
modes of light, a powerful resource for testing high dimensional quantum
phenomenon
The Leeds Winter Warmth Campaign: Stakeholder Evaluation
The winter of 2012/13 was longer and colder than usual; whilst temperatures were average in December, it was colder than usual from January through to May. March was the coldest it has been for 50 years (Met Office, 2013). This evaluation focuses on the organisations funded by the Winter Warmth campaign to deliver services to Leeds residents. The overriding aim of the evaluation was to inform the operation of possible future schemes, with good practices and any issues identified. The views of organisations on the need for the funds and how the campaign was organised were ascertained. How they delivered the services, reached clients and worked with other stakeholders is explored and their suggestions for improvements described. This report should be read alongside the overall campaign report, by Leeds City Council, and the beneficiary report
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