The RMS Survey: 6 cm continuum VLA observations towards candidate massive YSOs in the northern hemisphere

(Abridged) Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, well-selected sample of massive young stellar objects (MYSOs). We have identified $\sim$2000 MYSO candidates located throughout the Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. Aims: To identify the populations of UCHII regions and PNe within the sample and examine their Galactic distribution. Method: We have conducted high resolution radio continuum observations at 6 cm towards 659 MYSO candidates in the northern hemisphere (10\degr< l < 250\degr) using the VLA. In addition to these targeted observations we present archival data towards a further 315 RMS sources extracted from a previous VLA survey of the inner Galaxy. Results: We find radio emission towards 272 ($\sim$27% of the observed sample). Using results from other parts of our multi-wavelength survey we separate these RMS-radio associations into two distinct types of objects, classifying 51 as PNe and a further 208 as either compact or UC HII regions. Using this well selected sample of HII regions we estimate their Galactic scale height to be 0.6\degr. Conclusions: Using radio continuum and archival data we have identified 79 PNe and 391 HII regions within the northern RMS catalogue. We estimate the total fraction of contamination by PNe in the RMS sample is of order 10%. The sample of HII regions is probably the best representation to date of the Galactic population of HII regions as a whole.Comment: Accepted for publication in Astronomy and Astrophysics. 15 pages, 9 figures and 5 tables. Full versions of Tables 3, 4 and 5 and Figs. 2, 4 and 7 will only be available via CDS or the RMS website at http:/www.ast.leeds.ac.uk/cgi-bin/RMS/RMS_VLA_IMAGES.cg

The RMS Survey: Resolving kinematic distance ambiguities towards a sample of compact HII regions using HI absorption

We present high-resolution HI data obtained using the Australia Telescope Compact Array to resolve the near/far distance ambiguities towards a sample of compact HII regions from the Red MSX Source (RMS) survey. The high resolution data are complemented with lower resolution archival HI data extracted from the Southern and VLA Galactic Plane surveys. We resolve the distance ambiguity for nearly all of the 105 sources where the continuum was strong enough to allow analysis of the HI absorption line structure. This represents another step in the determination of distances to the total RMS sample, which with over 1,000 massive young stellar objects and compact HII regions, is the largest and most complete sample of its kind. The full sample will allow the distribution of massive star formation in the Galaxy to be examined.Comment: Accepted by MNRAS. This paper consists of 15 pages and contains 10 figures and 5 table

New ammonia masers towards NGC6334I

We report the detection of new ammonia masers in the non-metastable (8,6) and (11,9) transitions towards the massive star forming region NGC6334I. Observations were made with the ATCA interferometer and the emitting region appears unresolved in the 2.7" x 0.8" beam, with deconvolved sizes less than an arcsecond. We estimate peak brightness temperatures of 7.8 x 10^5 and 1.2 x 10^5 K for the (8,6) and (11,9) transitions, respectively. The masers appear coincident both spatially and in velocity with a previously detected ammonia (6,6) maser. We also suggest that emission in the (10,9), (9,9) and (7,6) transitions may also be masers, based on their narrow line widths and overlapping velocity ranges with the above masers, as observed with the single-dish Mopra radiotelescope

The RMS Survey: Distribution and properties of a sample of massive young stars

The Red MSX Source (RMS) survey has identified a large sample of massive young stellar objects (MYSOs) and ultra compact (UC) HII regions from a sample of ~2000 MSX and 2MASS colour selected sources. Using a recent catalogue of molecular clouds derived from the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (GRS), and by applying a Galactic scaleheight cut off of 120 pc, we solve the distance ambiguity for RMS sources located within 18\degr 54\degr. These two steps yield kinematic distances to 291 sources out of a possible 326 located within the GRS longitude range. Combining distances and integrated fluxes derived from spectral energy distributions, we estimate luminosities to these sources and find that > 90% are indicative of the presence of a massive star. We find the completeness limit of our sample is ~10^4 Lsun, which corresponds to a zero age main sequence (ZAMS) star with a mass of ~12 Msun. Selecting only these sources, we construct a complete sample of 196 sources. Comparing the properties of the sample of young massive stars with the general population, we find the RMS-clouds are generally larger, more massive, and more turbulent. We examine the distribution of this sub-sample with respect to the location of the spiral arms and the Galactic bar and find them to be spatially correlated. We identify three significant peaks in the source surface density at Galactocentric radii of approximately 4, 6 and 8 kpc, which correspond to the proposed positions of the Scutum, Sagittarius and Perseus spiral arms, respectively. Fitting a scale height to the data we obtain an average value of ~29+-0.5 pc, which agrees well with other reported values in the literature, however, we note a dependence of the scale height on galactocentric radius with it increases from 30 pc to 45 pc between 2.5 and 8.5 kpc.Comment: Accepted for publication by MNRAS. Paper consists of 15 pages including 12 figures and four tables. Full versions of Tables 2 and 3 will only be available online. The resolution of Figure 9 has been reduced - a full resolution version of the paper can be download from here: http://www.ast.leeds.ac.uk/cgi-bin/RMS/RMS_PUBLICATIONS.cg

Probing discs around massive young stellar objects with CO first overtone emission

We present high resolution (R~50,000) spectroastrometry over the CO 1st overtone bandhead of a sample of seven intermediate/massive young stellar objects. These are primarily drawn from the red MSX source (RMS) survey, a systematic search for young massive stars which has returned a large, well selected sample of such objects. The mean luminosity of the sample is approximately 5 times 10^4 L_\odot, indicating the objects typically have a mass of ~15 solar masses. We fit the observed bandhead profiles with a model of a circumstellar disc, and find good agreement between the models and observations for all but one object. We compare the high angular precision (0.2-0.8 mas) spectroastrometric data to the spatial distribution of the emitting material in the best-fitting models. No spatial signatures of discs are detected, which is entirely consistent with the properties of the best-fitting models. Therefore, the observations suggest that the CO bandhead emission of massive young stellar objects originates in small-scale disks, in agreement with previous work. This provides further evidence that massive stars form via disc accretion, as suggested by recent simulations.Comment: Accepted for publication in MNRA

The RMS Survey: Far-Infrared Photometry of Young Massive Stars

Context: The Red MSX Source (RMS) survey is a multi-wavelength campaign of follow-up observations of a colour-selected sample of candidate massive young stellar objects (MYSOs) in the galactic plane. This survey is returning the largest well-selected sample of MYSOs to date, while identifying other dust contaminant sources with similar mid-infrared colours including a large number of new ultra-compact (UC)HII regions. Aims:To measure the far-infrared (IR) flux, which lies near the peak of the spectral energy distribution (SED) of MYSOs and UCHII regions, so that, together with distance information, the luminosity of these sources can be obtained. Methods:Less than 50% of RMS sources are associated with IRAS point sources with detections at 60 micron and 100 micron, though the vast majority are visible in Spitzer MIPSGAL or IRAS Galaxy Atlas (IGA) images. However, standard aperture photometry is not appropriate for these data due to crowding of sources and strong spatially variable far-IR background emission in the galactic plane. A new technique using a 2-dimensional fit to the background in an annulus around each source is therefore used to obtain far-IR photometry for young RMS sources. Results:Far-IR fluxes are obtained for a total of 1113 RMS candidates identified as young sources. Of these 734 have flux measurements using IGA 60 micron and 100 micron images and 724 using MIPSGAL 70 micron images, with 345 having measurements in both data sets.Comment: 10 pages, 10 figures, 2 Tables, accepted to A&A. A full version of table 1 is available from the lead author or at the CDS upon publicatio

Characterisation of the Mopra Radio Telescope at 16--50 GHz

We present the results of a programme of scanning and mapping observations of astronomical masers and Jupiter designed to characterise the performance of the Mopra Radio Telescope at frequencies between 16-50 GHz using the 12-mm and 7-mm receivers. We use these observations to determine the telescope beam size, beam shape and overall telescope beam efficiency as a function of frequency. We find that the beam size is well fit by $\lambda$/$D$ over the frequency range with a correlation coefficient of ~90%. We determine the telescope main beam efficiencies are between ~48-64% for the 12-mm receiver and reasonably flat at ~50% for the 7-mm receiver. Beam maps of strong H$_2$O (22 GHz) and SiO masers (43 GHz) provide a means to examine the radial beam pattern of the telescope. At both frequencies the radial beam pattern reveals the presence of three components, a central `core', which is well fit by a Gaussian and constitutes the telescopes main beam, and inner and outer error beams. At both frequencies the inner and outer error beams extend out to approximately 2 and 3.4 times the full-width half maximum of the main beam respectively. Sources with angular sizes a factor of two or more larger than the telescope main beam will couple to the main and error beams, and therefore the power contributed by the error beams needs to be considered. From measurements of the radial beam power pattern we estimate the amount of power contained in the inner and outer error beams is of order one-fifth at 22 GHz rising slightly to one-third at 43 GHz.Comment: Accepted for publication in PAS

Psychological Aspects of Children and Adolescents With Duchenne Muscular Dystrophy (DMD) and Research Portfolio

This paper reviews the extant literature on the psychological aspects of Duchenne Muscular Dystrophy (DMD) and discusses the clinical implications of its impact on children and their families. DIVID is the commonest form of muscular dystrophy and the most severe, following a progressive and fatal course of muscular weakness and deterioration. Research on psychological aspects of DMD is rather old and restricted to a small number of studies of varying methodological quality. However, the clinical presentation of DMD, the developmental stage of the child, social/environmental restrictions and family interactions have all been implicated in psychological difficulties within this group. Seminal work and directly relevant research from other areas is discussed and suggestions are made to guide both research and service provision