The structure of Onsala 1 star forming region

We present new high-sensitivity high-resolution mm-wave observations of the Onsala 1 ultra-compact HII region that bring to light the internal structure of this massive star forming cloud. The 1.2 mm continuum map obtained with the IRAM 30-m radiotelescope (~11" resolution) shows a centrally peaked condensation of 1' size (~0.5 pc at the assumed distance of 1.8 kpc) which has been further investigated at higher resolution in the 3 mm continuum and in the emission lines of H13CO+ J=1--0 and SiO J=2--1 with the IRAM Plateau de Bure interferometer. The 3 mm data, with a resolution of ~5" X 4", displays a unresolved continuum source at the peak of the extended 1.2 mm emission and closely associated with the ultra-compact HII region. The H13CO+ map traces the central condensation in good agreement with previous NH_3 maps of Zheng et al. (1985). However, the velocity field of this central condensation, which was previously thought to arise in a rapidly rotating structure, is better explained in terms of the dense and compact component of a bipolar outflow. This interpretation is confirmed by SiO and CO observations of the full region. In fact, our new SiO data unveils the presence of multiple (at least 4) outflows in the region. In particular, there is an important center of outflow activity in the region at about 1' north of the UCHII region. Indeed the different outflows are related to different members of the Onsala 1 cluster. The data presented here support a scenario in which the phases of massive star formation begin much later in the evolution of a cluster and/or UCHII region last for much longer than 10^5 yrs.Comment: 6 pages and 3 figure

Spatially-resolved Thermal Continuum Absorption against the Supernova Remnant W49B

We present sub-arcminute resolution imaging of the Galactic supernova remnant W49B at 74 MHz (25") and 327 MHz (6"), the former being the lowest frequency at which the source has been resolved. While the 327 MHz image shows a shell-like morphology similar to that seen at higher frequencies, the 74 MHz image is considerably different, with the southwest region of the remnant almost completely attenuated. The implied 74 MHz optical depth (~ 1.6) is much higher than the intrinsic absorption levels seen inside two other relatively young remnants, Cas A and the Crab Nebula, nor are natural variations in the relativistic electron energy spectra expected at such levels. The geometry of the absorption is also inconsistent with intrinsic absorption. We attribute the absorption to extrinsic free-free absorption by a intervening cloud of thermal electrons. Its presence has already been inferred from the low-frequency turnover in the integrated continuum spectrum and from the detection of radio recombination lines toward the remnant. Our observations confirm the basic conclusions of those measurements, and our observations have resolved the absorber into a complex of classical HII regions surrounded either partially or fully by low-density HII gas. We identify this low-density gas as an extended HII region envelope (EHE), whose statistical properties were inferred from low resolution meter- and centimeter-wavelength recombination line observations. Comparison of our radio images with HI and H_2CO observations show that the intervening thermal gas is likely associated with neutral and molecular material as well.Comment: 18 pages, LaTeX with AASTeX-5, 5 figures in 7 PostScript files; accepted for publication in the Ap

A Low Frequency Survey of the Galactic Plane Near l=11 degrees: Discovery of Three New Supernova Remnants

We have imaged a 1 deg^2 field centered on the known Galactic supernova remnant (SNR) G11.2-0.3 at 74, 330, and 1465 MHz with the Very Large Array radio telescope (VLA) and 235 MHz with the Giant Metrewave Radio Telescope (GMRT). The 235, 330, and 1465 MHz data have a resolution of 25 arcsec, while the 74 MHz data have a resolution of 100 arcsec. The addition of this low frequency data has allowed us to confirm the previously reported low frequency turnover in the radio continuum spectra of the two known SNRs in the field: G11.2-0.3 and G11.4-0.1 with unprecedented precision. Such low frequency turnovers are believed to arise from free-free absorption in ionized thermal gas along the lines of site to the SNRs. Our data suggest that the 74 MHz optical depths of the absorbing gas is 0.56 and 1.1 for G11.2-0.3 and G11.4-0.1, respectively. In addition to adding much needed low frequency integrated flux measurements for two known SNRs, we have also detected three new SNRs: G11.15-0.71, G11.03-0.05, and G11.18+0.11. These new SNRs have integrated spectral indices between -0.44 and -0.80. Because of confusion with thermal sources, the high resolution (compared to previous Galactic radio frequency surveys) and surface brightness sensitivity of our observations have been essential to the identification of these new SNRs. With this study we have more than doubled the number of SNRs within just a 1 deg^2 field of view in the inner Galactic plane. This result suggests that future low frequency observations of the Galactic plane of similar quality may go a long way toward alleviating the long recognized incompleteness of Galactic SNR catalogs.Comment: 31 pages, 9 figures. Figure 7 is in color. Accepted to A

A disk of dust and molecular gas around a high-mass protostar

The processes leading to the birth of low-mass stars such as our Sun have been well studied, but the formation of high-mass (> 8 x Sun's mass) stars has heretofore remained poorly understood. Recent observational studies suggest that high-mass stars may form in essentially the same way as low-mass stars, namely via an accretion process, instead of via merging of several low-mass (< 8 Msun) stars. However, there is as yet no conclusive evidence. Here, we report the discovery of a flattened disk-like structure observed at submillimeter wavelengths, centered on a massive 15 Msun protostar in the Cepheus-A region. The disk, with a radius of about 330 astronomical units (AU) and a mass of 1 to 8 Msun, is detected in dust continuum as well as in molecular line emission. Its perpendicular orientation to, and spatial coincidence with the central embedded powerful bipolar radio jet, provides the best evidence yet that massive stars form via disk accretion in direct analogy to the formation of low-mass stars

Physical Conditions in the Foreground Gas of Reflection Nebulae: NGC 2023, vdB 102, and NGC 7023

High resolution optical spectra of HD 37903 and HD 147009, which illuminate the reflection nebulae, NGC 2023 and vdB 102, were obtained for comparison with our results for HD 200775 and NGC 7023. Ground-based measurements of the molecules, CH, C$_2$, and CN, and the atoms, Na I and K I, were analyzed to extract physical conditions in the foreground cloud. Estimates of the gas density, gas temperature and flux of ultraviolet radiation were derived and were compared with the results from infrared and radio studies of the main molecular cloud. The conditions are similar to those found in studies of diffuse clouds. The foreground material is less dense than the gas in the molecular cloud behind the star(s). The gas temperature was set at 40 K, the temperature determined for the foreground gas in NGC 7023. The flux of ultraviolet radiation was found to be less intense than in the molecular material behind the star(s). The column densities of Na I and K I were reproduced reasonably well when the extinction curve for the specific line of sight was adopted. We obtained NEWSIPS data from the IUE archive for HD 37903 and HD 200775. The ultraviolet data on C I and CO allow extraction of the physical conditions by alternate methods. General agreement among the various diagnostics was found, leading to self-consistent pictures of the foreground photodissociation regions. An Appendix describes checks on the usefulness of IUE NEWSIPS data for interstellar studies. (Abridged)Comment: 65 pages, 18 tables, 14 figures, Accepted for publication in ApJ

Carbon Recombination Lines from the Galactic Plane at 34.5 & 328 MHz

We present results of a search for carbon recombination lines in the Galaxy at 34.5 MHz (C$575\alpha$) made using the dipole array at Gauribidanur near Bangalore. Observations made towards 32 directions, led to detections of lines in absorption at nine positions. Followup observations at 328 MHz (C$272\alpha$) using the Ooty Radio Telescope detected these lines in emission. A VLA D-array observation of one of the positions at 330 MHz yielded no detection implying a lower limit of 10' for the angular size of the line forming region. The longitude-velocity distribution of the observed carbon lines indicate that the line forming region are located mainly between 4 kpc and 7 kpc from the Galactic centre. Combining our results with published carbon recombination line data near 76 MHz (\nocite{erickson:95} Erickson \et 1995) we obtain constraints on the physical parameters of the line forming regions. We find that if the angular size of the line forming regions is $\ge 4^{\circ}$, then the range of parameters that fit the data are: \Te $= 20-40$ K, \ne $\sim 0.1-0.3$ \cm3 and pathlengths $\sim 0.07-0.9$ pc which may correspond to thin photo-dissociated regions around molecular clouds. On the other hand, if the line forming regions are $\sim 2^{\circ}$ in extent, then warmer gas (\Te $\sim 60-300$ K) with lower electron densities (\ne $\sim 0.03-0.05$ \cm3) extending over several tens of parsecs along the line of sight and possibly associated with atomic \HI gas can fit the data. Based on the range of derived parameters, we suggest that the carbon line regions are most likely associated with photo-dissociation regions.Comment: To appear in Journal of Astrophysics & Astronomy, March 200

Photoevaporation Flows in Blister HII Regions: I. Smooth Ionization Fronts and Application to the Orion Nebula

We present hydrodynamical simulations of the photoevaporation of a cloud with large-scale density gradients, giving rise to an ionized, photoevaporation flow. The flow is found to be approximately steady during the large part of its evolution, during which it can resemble a "champagne flow" or a "globule flow" depending on the curvature of the ionization front. The distance from source to ionization front and the front curvature uniquely determine the structure of the flow, with the curvature depending on the steepness of the lateral density gradient in the neutral cloud. We compare these simulations with both new and existing observations of the Orion nebula and find that a model with a mildly convex ionization front can reproduce the profiles of emission measure, electron density, and mean line velocity for a variety of emitting ions on scales of 10^{17} to 10^{18} cm. The principal failure of our model is that we cannot explain the large observed widths of the [O I] 6300 Angstrom line that forms at the ionization front.Comment: 21 pages, accepted for publication in The Astrophysical Journa

Testing grain-surface chemistry in massive hot-core regions

A partial submillimeter line-survey was performed toward 7 high-mass young stellar objects (YSOs) aimed at detecting H2CO, CH3OH, CH2CO, CH3CHO, C2H5OH, HCOOH, HNCO and NH2CHO. In addition, other organic species such as CH3CN have been observed. The aim is to establish the chemical origin of a set of complex organic molecules thought to be produced by grain surface chemistry in high mass YSOs. Rotation temperatures and beam-averaged column densities are determined. Based on their rotation diagrams, molecules can be classified as either cold (100 K). This implies that complex organics are present in at least two distinct regions. Furthermore, the abundances of the hot oxygen-bearing species are correlated, as are those of HNCO and NH2CHO. This is suggestive of chemical relationships within, but not between, those two groups of molecules. The most likely explanation for the observed correlations of the various hot molecules is that they are ``first generation'' species that originate from solid-state chemistry. This includes H2CO, CH3OH, C2H5OH, HCOOCH3, CH3OCH3, HNCO, NH2CHO, and possibly CH3CN, and C2H5CN. The correlations between sources implies very similar conditions during their formation or very similar doses of energetic processing. Cold species such as CH2CO, CH3CHO, and HCOOH, some of which are seen as ices along the same lines of sight, are probably formed in the solid state as well, but appear to be destroyed at higher temperatures. A low level of non-thermal desorption by cosmic rays can explain their low rotation temperatures and relatively low abundances in the gas phase compared to the solid state. The CH3CCH abundances can be fully explained by low temperature gas phase chemistry. No cold N-containing molecules are found.Comment: 20 pages, 8 figures, accepted by Astronomy and Astrophysic

Public health in community pharmacy: a systematic review of pharmacist and consumer views

BACKGROUND The increasing involvement of pharmacists in public health will require changes in the behaviour of both pharmacists and the general public. A great deal of research has shown that attitudes and beliefs are important determinants of behaviour. This review aims to examine the beliefs and attitudes of pharmacists and consumers towards pharmaceutical public health in order to inform how best to support and improve this service. METHODS Five electronic databases were searched for articles published in English between 2001 and 2010. Titles and abstracts were screened by one researcher according to the inclusion criteria. Papers were included if they assessed pharmacy staff or consumer attitudes towards pharmaceutical public health. Full papers identified for inclusion were assessed by a second researcher and data were extracted by one researcher. RESULTS From the 5628 papers identified, 63 studies in 67 papers were included. Pharmacy staff: Most pharmacists viewed public health services as important and part of their role but secondary to medicine related roles. Pharmacists' confidence in providing public health services was on the whole average to low. Time was consistently identified as a barrier to providing public health services. Lack of an adequate counselling space, lack of demand and expectation of a negative reaction from customers were also reported by some pharmacists as barriers. A need for further training was identified in relation to a number of public health services. Consumers: Most pharmacy users had never been offered public health services by their pharmacist and did not expect to be offered. Consumers viewed pharmacists as appropriate providers of public health advice but had mixed views on the pharmacists' ability to do this. Satisfaction was found to be high in those that had experienced pharmaceutical public health. CONCLUSIONS There has been little change in customer and pharmacist attitudes since reviews conducted nearly 10 years previously. In order to improve the public health services provided in community pharmacy, training must aim to increase pharmacists' confidence in providing these services. Confident, well trained pharmacists should be able to offer public health service more proactively which is likely to have a positive impact on customer attitudes and health

Multi-line detection of O2 toward rho Oph A

Models of pure gas-phase chemistry in well-shielded regions of molecular clouds predict relatively high levels of molecular oxygen, O2, and water, H2O. Contrary to expectation, the space missions SWAS and Odin found only very small amounts of water vapour and essentially no O2 in the dense star-forming interstellar medium. Only toward rho Oph A did Odin detect a weak line of O2 at 119 GHz in a beam size of 10 arcmin. A larger telescope aperture such as that of the Herschel Space Observatory is required to resolve the O2 emission and to pinpoint its origin. We use the Heterodyne Instrument for the Far Infrared aboard Herschel to obtain high resolution O2 spectra toward selected positions in rho Oph A. These data are analysed using standard techniques for O2 excitation and compared to recent PDR-like chemical cloud models. The 487.2GHz line was clearly detected toward all three observed positions in rho Oph A. In addition, an oversampled map of the 773.8GHz transition revealed the detection of the line in only half of the observed area. Based on their ratios, the temperature of the O2 emitting gas appears to vary quite substantially, with warm gas (> 50 K) adjacent to a much colder region, where temperatures are below 30 K. The exploited models predict O2 column densities to be sensitive to the prevailing dust temperatures, but rather insensitive to the temperatures of the gas. In agreement with these model, the observationally determined O2 column densities seem not to depend strongly on the derived gas temperatures, but fall into the range N(O2) = (3 to >6)e15/cm^2. Beam averaged O2 abundances are about 5e-8 relative to H2. Combining the HIFI data with earlier Odin observations yields a source size at 119 GHz of about 4 - 5 arcmin, encompassing the entire rho Oph A core.Comment: 10 pages, 8 figures intended for publication in A&