Search

The H2O Southern Galactic Plane Survey (HOPS) has mapped 100 square degrees of the Galactic plane for water masers and thermal molecular line emission using the 22-m Mopra telescope. We describe the automated spectral-line fitting pipelines used to determine the properties of emission detected in HOPS datacubes, and use these to derive the physical and kinematic properties of gas in the survey. A combination of the angular resolution, sensitivity, velocity resolution and high critical density of lines targeted make the HOPS data cubes ideally suited to finding precursor clouds to the most massive and dense stellar clusters in the Galaxy. We compile a list of the most massive HOPS ammonia regions and investigate whether any may be young massive cluster progenitor gas clouds. HOPS is also ideally suited to trace the flows of dense gas in the Galactic Centre. We find the kinematic structure of gas within the inner 500pc of the Galaxy is consistent with recent predictions for the dynamical evolution of gas flows in the centre of the Milky Way. We confirm a recent finding that the dense gas in the inner 100pc has an oscillatory kinematic structure with characteristic length scale of ~20pc, and also identify similar oscillatory kinematic structure in the gas at radii larger than 100pc. Finally, we make all of the above fits and the remaining HOPS data cubes across the 100 square degrees of the survey available to the community., Comment: 53 pages, 34 figures, 4 tables. Submitted MNRAS. Paper with full resolution images can be downloaded here: http://www.astro.ljmu.ac.uk/~snl/hops_p3.pdf

Radio continuum observations using the Australia telescope compact array at 5.5, 9.0, 17.0 and 22.8 GHz have detected free-free emission associated with 45 of 49 massive young stellar objects and HII regions. Of these, 26 sources are classified as ionized jets (12 of which are candidates), 2 as ambiguous jets or disc winds, 1 as a disc-wind, 14 as HII regions and 2 were unable to be categorised. Classification as ionized jets is based upon morphology, radio flux and spectral index, in conjunction with previous observational results at other wavelengths. Radio-luminosity and momentum are found to scale with bolometric luminosity in the same way as low-mass jets, indicating a common mechanism for jet production across all masses. In 13 of the jets, we see associated non-thermal/optically-thin lobes resulting from shocks either internal to the jet and/or at working surfaces. Ten jets display non-thermal (synchrotron emission) spectra in their lobes, with an average spectral index of -0.55 consistent with Fermi acceleration in shocks. This shows that magnetic fields are present, in agreement with models of jet formation incorporating magnetic fields. Since the production of collimated radio jets is associated with accretion processes, the results presented in this paper support the picture of disc-mediated accretion for the formation of massive stars with an upper-limit on the jet phase lasting approximately $6.5 \times 10^4 yr$. Typical mass loss rates in the jet are found to be $1.4 \times 10^{-5} M_\odot yr^{-1}$ with associated momentum rates of the order $(1-2) \times 10^{-2} M_\odot km s^{-1} yr^{-1}$.

The amount of high-energy stellar radiation reaching the surface of protoplanetary disks is essential to determine their chemistry and physical evolution. Here, we use millimetric and centimetric radio data to constrain the EUV luminosity impinging on 14 disks around young (~2-10Myr) sun-like stars. For each object we identify the long-wavelength emission in excess to the dust thermal emission, attribute that to free-free disk emission, and thereby compute an upper limit to the EUV reaching the disk. We find upper limits lower than 10$^{42}$ photons/s for all sources without jets and lower than $5 \times 10^{40}$ photons/s for the three older sources in our sample. These latter values are low for EUV-driven photoevaporation alone to clear out protoplanetary material in the timescale inferred by observations. In addition, our EUV upper limits are too low to reproduce the [NeII] 12.81 micron luminosities from three disks with slow [NeII]-detected winds. This indicates that the [NeII] line in these sources primarily traces a mostly neutral wind where Ne is ionized by 1 keV X-ray photons, implying higher photoevaporative mass loss rates than those predicted by EUV-driven models alone. In summary, our results suggest that high-energy stellar photons other than EUV may dominate the dispersal of protoplanetary disks around sun-like stars., Comment: Accepted for publication to The Astrophysical Journal

The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey aims to characterise the physical and chemical evolution of high-mass star-forming clumps. Exploiting the unique broad frequency range and on-the-fly mapping capabilities of the Australia Telescope National Facility Mopra 22 m single-dish telescope, MALT90 has obtained 3' x 3' maps toward ~2000 dense molecular clumps identified in the ATLASGAL 870 um Galactic plane survey. The clumps were selected to host the early stages of high-mass star formation and to span the complete range in their evolutionary states (from prestellar, to protostellar, and on to HII regions and photodissociation regions). Because MALT90 mapped 16 lines simultaneously with excellent spatial (38") and spectral (0.11 km/s) resolution, the data reveal a wealth of information about the clump's morphologies, chemistry, and kinematics. In this paper we outline the survey strategy, observing mode, data reduction procedure, and highlight some early science results. All MALT90 raw and processed data products are available to the community. With its unprecedented large sample of clumps, MALT90 is the largest survey of its type ever conducted and an excellent resource for identifying interesting candidates for high resolution studies with ALMA., Comment: Accepted to PASA, 13 pages

The H2O Southern Galactic Plane Survey (HOPS) has mapped a 100 degree strip of the Galactic plane (-70deg > l > 30deg, |b| < 0.5deg) using the 22-m Mopra antenna at 12-mm wavelengths. Observations were conducted in on-the-fly mode using the Mopra spectrometer (MOPS), targeting water masers, thermal molecular emission and radio-recombination lines. Foremost among the thermal lines are the 23 GHz transitions of NH3 J,K = (1,1) and (2,2), which trace the densest parts of molecular clouds (n > 10^4 cm^{-3}). In this paper we present the NH3 (1,1) and (2,2) data, which have a resolution of 2 arcmin and cover a velocity range of +/-200 km/s. The median sensitivity of the NH3 data-cubes is sigma_Tmb = 0.20 +/1 0.06 K. For the (1,1) transition this sensitivity equates to a 3.2 kpc distance limit for detecting a 20 K, 400 Msun cloud at the 5-sigma level. Similar clouds of mass 5,000 Msun would be detected as far as the Galactic centre, while 30,000 Msun clouds would be seen across the Galaxy. We have developed an automatic emission finding procedure based on the ATNF DUCHAMP software and have used it to create a new catalogue of 669 dense molecular clouds. The catalogue is 100 percent complete at the 5-sigma detection limit (Tmb = 1.0 K). A preliminary analysis of the ensemble cloud properties suggest that the near kinematic distances are favoured. The cloud positions are consistent with current models of the Galaxy containing a long bar. Combined with other Galactic plane surveys this new molecular-line dataset constitutes a key tool for examining Galactic structure and evolution. Data-cubes, spectra and catalogues are available to the community via the HOPS website., Comment: 22 pages, 19 figures. Accepted for publication in MNRAS (25-July-2012)

We present first results of the H_2O Southern Galactic Plane Survey (HOPS), using the Mopra radiotelescope with a broad band backend and a beam size of about 2'. We have observed 100 square degrees of the southern Galactic plane at 12mm (19.5 to 27.5GHz), including spectral line emission from water masers, multiple metastable transitions of ammonia, cyanoacetylene, methanol and radio recombination lines. In this paper, we report on the characteristics of the survey and water maser emission. We find 540 water masers, of which 334 are new detections. The strongest maser is 3933Jy and the weakest is 0.7Jy, with 62 masers over 100Jy. In 14 maser sites, the spread in velocity of the water maser emission exceeds 100km/s. In one region, the water maser velocities are separated by 351.3km/s. The rms noise levels are typically between 1-2Jy, with 95% of the survey under 2Jy. We estimate completeness limits of 98% at around 8.4Jy and 50% at around 5.5Jy. We estimate that there are between 800 and 1500 water masers in the Galaxy that are detectable in a survey with similar completeness limits to HOPS. We report possible masers in NH_3 (11,9) and (8,6) emission towards G19.61-0.23 and in the NH_3 (3,3) line towards G23.33-0.30., Comment: accepted for publication in MNRAS

We report molecular line observations in the CO J=3$\rightarrow$2, 6$\rightarrow$5 and 7$\rightarrow$6 transitions, made using the Atacama Pathfinder Experiment Telescope (APEX), toward the massive and dense core IRAS 16562$-$3959. This core harbors a string of radio sources thought to be powered by a central collimated jet of ionized gas. The molecular observations show the presence of high velocity gas exhibiting a quadrupolar morphology, most likely produced by the presence of two collimated outflows. The southeast-northwest molecular outflow is aligned with the string of radio continuum sources, suggesting it is driven by the jet. We find that the excitation temperature of the gas in the SE-NW outflow is high, with values of 145 and 120 K for the blueshifted and redshifted lobes, respectively. This outflow has a total mass of 1.92 \Msun, a total momentum of $\sim 89$ \Msun \kms and an averaged momentum rate of $\sim 3.0\times10^{-2}$ \Msun \kms yr$^{-1}$, values characteristics of flows driven by young massive stellar objects with high luminosities ($L_{\rm bol} \sim 2\times10^4$ \Lsun). Complementary data taken with the Atacama Submillimeter Telescope Experiment (ASTE) in high density and shock tracers support the picture that IRAS 16562$-$3959 is an accreting young massive star associated with an ionized jet, which is the energy source of a molecular outflow., Comment: Accepted for publication in the ApJ

We present the sub-mm/mm SED for a sample of eight young circumstellar disks in the outer regions of the Orion Nebula Cluster. New observations were carried out at 2.9 mm with the CARMA array and for one disk, 216-0939, at 3.3 and 6.8 mm with ATCA. By combining these new millimeter data with literature measurements at sub-millimeter wavelengths we investigate grain growth and measure the dust mass in protoplanetary disks in the Orion Nebula Cluster. These data provide evidence for dust grain growth to at least millimeter-sizes for the first time in a high-mass star forming region. The obtained range in sub-mm/mm spectral index, namely 1.5-3.2, indicates that for disks in the outskirts of the Orion Nebula Cluster (projected distance from the cluster center between about 0.4 pc and 1.5 pc) grain growth to mm sizes occurs in the same manner as disks in regions where only low-mass stars form. Finally, in our sample three disks are more massive than about $0.05\,M_\odot$, confirming that massive disks are present in the outer regions of the Orion Nebula., Comment: 5 pages, 4 figures, accepted for publication in A&A

We present new ATCA observations at 3.3 mm of 27 young stellar objects in the rho-Oph young cluster. 25 of these sources have been detected. We analyze the sub-millimeter and millimeter SED for a subsample of 17 isolated class II protoplanetary disks and derive constraints on the grain growth and total dust mass in the disk outer regions. All the disks in our sample show a mm slope of the SED which is significantly shallower than the one observed for the ISM at these long wavelengths. This indicates that 1) class II disks in Ophiuchus host grains grown to mm/cm-sizes in their outer regions, 2) formation of mm/cm-sized pebbles is a fast process and 3) a mechanism halting or slowing down the inward radial drift of solid particles is required to explain the data. These findings are consistent with previous results in other star forming regions. We compare the dust properties of this sample with those of a uniformly selected sample in Taurus-Auriga and find no statistical evidence of any difference in terms of grain growth between the two regions. Finally, in our sample the mm slope of the SED is not found to correlate with indicators of grain growth to micron sizes in the surface layers of the inner disk., Comment: 12 pages, 8 figures, accepted for publication in A&A

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 PASA

We have conducted a Galactic plane survey of methanol masers at 6668 MHz using a 7-beam receiver on the Parkes telescope. Here we present results from the first part, which provides sensitive unbiased coverage of a large region around the Galactic Centre. Details are given for 183 methanol maser sites in the longitude range 345$^{\circ}$ through the Galactic Centre to 6$^{\circ}$. Within 6$^{\circ}$ of the Centre, we found 88 maser sites, of which more than half (48) are new discoveries. The masers are confined to a narrow Galactic latitude range, indicative of many sources at the Galactic Centre distance and beyond, and confined to a thin disk population; there is no high latitude population that might be ascribed to the Galactic Bulge. Within 2$^{\circ}$ of the Galactic Centre the maser velocities all lie between -60 and +77 \kms, a range much smaller than the 540 \kms range observed in CO. Elsewhere, the maser with highest positive velocity (+107 \kms) occurs, surprisingly, near longitude 355$^{\circ}$ and is probably attributable to the Galactic bar. The maser with the most negative velocity (-127 \kms) is near longitude 346$^{\circ}$, within the longitude-velocity locus of the near side of the `3-kpc arm'. It has the most extreme velocity of a clear population of masers associated with the near and far sides of the 3-kpc arm. Closer to the Galactic Centre the maser space density is generally low, except within 0.25 kpc of the Centre itself, the `Galactic Centre Zone', where it is 50 times higher, which is hinted at by the longitude distribution, and confirmed by the unusual velocities., Comment: 35 pages, 5 figures

The Australia Telescope Compact Array (ATCA) and the Mopra facility have been used to search for new southern class I methanol masers at 9.9, 25 (J=5) and 104 GHz, which are thought to trace more energetic conditions in the interface regions of molecular outflows, than the widespread class I masers at 44 and 95 GHz. One source shows a clear outflow association., Comment: 2 pages, 1 figure (composed from 3 files), to appear in proceedings of IAU Symposium 242 "Astrophysical masers and their environment" (eds. J. Chapman and W. Baan)

The Australia Telescope Compact Array (ATCA) has been used to image class I methanol masers at 9.9, 25 (a series from J=2 to J=9), 84, 95 and 104 GHz located in the vicinity of IRAS 16547-4247 (G343.12-0.06), a luminous young stellar object known to harbour a radio jet. The detected maser emission consists of a cluster of 6 spots spread over an area of 30 arcsec. Five spots were detected in only the 84- and 95-GHz transitions (for two spots the 84-GHz detection is marginal), while the sixth spot shows activity in all 12 observed transitions. We report the first interferometric observations of the rare 9.9- and 104-GHz masers. It is shown that the spectra contain a very narrow spike (<0.03 km/s) and the brightness temperature in these two transitions exceeds 5.3x10^7 and 2.0x10^4 K, respectively. The three most southern maser spots show a clear association with the shocked gas traced by the H_2 2.12 micron emission associated with the radio jet and their velocities are close to that of the molecular core within which the jet is embedded. This fact supports the idea that the class I masers reside in the interface regions of outflows. Comparison with OH masers and infrared data reveals a potential discrepancy in the expected evolutionary state. The presence of the OH masers usually means that the source is evolved, but the infrared data suggest otherwise. The lack of any class II methanol maser emission at 6.7 GHz in the source raises an additional question, is this source too young or too old to have a 6.7 GHz maser? We argue that both cases are possible and suggest that the evolutionary stage where the class I masers are active, may last longer and start earlier than when the class II masers are active. However, it is currently not possible to reveal the exact evolutionary status of IRAS 16547-4247., Comment: 14 pages, 6 figures, 4 tables, accepted by MNRAS

A triple radio source recently detected in association with the luminous infrared source IRAS 16547-4247 has been studied with high angular resolution and high sensitivity with the Very Large Array at 3.6 and 2 cm. Our observations confirm the interpretation that the central object is a thermal radio jet, while the two outer lobes are most probably heavily obscured HH objects. The thermal radio jet is resolved angularly for the first time and found to align closely with the outer lobes. The opening angle of the thermal jet is estimated to be $\sim 25^\circ$, confirming that collimated outflows can also be present in massive protostars. The proper motions of the outer lobes should be measurable over timescales of a few years. Several fainter sources detected in the region are most probably associated with other stars in a young cluster., Comment: 9 pages, 2 figures

Results are presented from a multi-wavelength study of the giant pillars within the Carina Nebula. Using near-IR data from 2MASS, mid-IR data from MSX, 843MHz radio continuum maps from the MOST, and molecular line and continuum observations from the SEST, we investigate the nature of the pillars and search for evidence of ongoing star formation within them. Photodissociation regions (PDRs) exist across the whole nebula and trace the giant pillars, as well as many ridges, filaments, and condensations (Av > 7 mag). Morphological similarities between emission features at 21um and 843MHz adjacent to the PDRs, suggests that the molecular material has been carved by the intense stellar winds and UV radiation from the nearby massive stars. In addition, star forming cores are found at the tips of several of the pillars. Using a stellar density distribution, several candidate embedded clusters are also found. One is clearly seen in the 2MASS images and is located within a dense core (G287.84-0.82). A search for massive young stellar objects and compact HII regions using mid-IR colour criteria, reveal twelve candidates across the complex. Grey-body fits to SEDs for four of these objects are suggestive of OB-stars. We find that massive star formation in the Carina Nebula is occurring across the whole complex and confirm it has been continuous over the past 3 Myrs., Comment: 14 pages, 10 figures (low resolution), accepted by A&A

IRAS 16547-4247 is the most luminous (6.2 x 10^4 Lsun) embedded young stellar object known to harbor a thermal radio jet. We report the discovery using VLT-ISAAC of a chain of H_2 2.12 um emission knots that trace a collimated flow extending over 1.5 pc. The alignment of the H_2 flow and the central location of the radio jet implies that these phenomena are intimately linked. We have also detected using TIMMI2 an isolated, unresolved 12 um infrared source towards the radio jet . Our findings affirm that IRAS 16547-4247 is excited by a single O-type star that is driving a collimated jet. We argue that the accretion mechanism which produces jets in low-mass star formation also operates in the higher mass regime., Comment: Accepted for publication in ApJL, 10 pages, 2 figures

Here we present the discovery of a triple radio continuum source associated with IRAS 16547-4247. The spectral indices of the three components are consistent with a jet powered by a massive O-type star in the process of formation, with the outer radio components being the shocked gas at the working surfaces of the jet. The detected radio continuum emission from the central object is thought to arise from the jet itself, prior to the formation of a detectable HII region. All three radio continuum components are located within a molecular core of mass 10^3 M_sun. Our discovery makes IRAS 16547-4247 the most luminous (6.2 x 10^4 L_sun) young stellar object from which a thermal jet emanates, suggesting that the mechanism that produces jets in low-mass star formation also operates in high-mass star formation., Comment: 3 pages, 1 figure, to be published in RevMexAA(SC) Winds Bubbles and Explosions, 9 - 13 September 2002, Patzcuaro, Mexico

We present results from a study of two luminous IRAS sources thought to be young massive star-forming regions and which have no previously detected radio continuum emission: IRAS 15596-5301 and IRAS 16272-4837. Our study incorporates sensitive ATCA radio continuum data, SEST 1.2-mm continuum (using the new SIMBA bolometer) and line data, as well as data taken from the MSX database. The results show that both sources are associated with dense molecular cores which appear to host recently formed massive stars. We argue that IRAS16272 is in a very early stage of evolution, prior to the formation of an ultra compact HII region and that IRAS15596 is in a more advanced stage and hosts a cluster of B-type stars., Comment: 5 pages, 4 figures, conference proceedings: Galactic Star Formation Across the Stellar Mass Spectrum

We have obtained wide-field thermal infrared (IR) images of the Carina Nebula, using the SPIREX/Abu telescope at the South Pole. Emission from poly-cyclic aromatic hydrocarbons (PAHs) at 3.29um, a tracer of photodissociation regions (PDRs), reveals many interesting well defined clumps and diffuse regions throughout the complex. Near-IR images (1--2um), along with images from the Midcourse Space Experiment (MSX) satellite (8--21um) were incorporated to study the interactions between the young stars and the surrounding molecular cloud in more detail. Two new PAH emission clumps have been identified in the Keyhole Nebula and were mapped in 12CO(2--1) and (1--0) using the SEST. Analysis of their physical properties reveals they are dense molecular clumps, externally heated with PDRs on their surfaces and supported by external pressure in a similar manner to the other clumps in the region. A previously identified externally heated globule containing IRAS 10430-5931 in the southern molecular cloud, shows strong 3.29-, 8- and 21-um emission, the spectral energy distribution (SED) revealing the location of an ultra-compact (UC) HII region. The northern part of the nebula is complicated, with PAH emission inter-mixed with mid-IR dust continuum emission. Several point sources are located here and through a two-component black-body fit to their SEDs, we have identified 3 possible UC HII regions as well as a young star surrounded by a circumstellar disc. This implies that star formation in this region is on-going and not halted by the intense radiation from the surrounding young massive stars., Comment: 14 pages, 12 figures. Accepted by MNRAS. Higher resolution figures available at http://www.phys.unsw.edu.au/~jmr/papers.html

We present preliminary results from a detailed study towards four previously detected bright mid-infrared sources in the southern part of the Carina Nebula: G287.73--0.92, G287.84--0.82, G287.93--0.99 and G288.07--0.80. All of these sources are located at the heads of giant dust pillars that point towards the nearby massive star cluster, Trumpler 16. It is unclear if these pillars are the prime sites for a new generation of triggered star formation or if instead they are the only remaining parts of the nebula where ongoing star fromation can take place., Comment: 2 pages, to appear in the proceedings of "Hot Star Workshop III: The Earliest Phases of Massive Star Birth" (ed. P.A. Crowther)

We present results from observations of H110alpha recombination-line emission at 4.874 GHz and the related 4.8-GHz continuum emission towards the Carina Nebula using the Australia Telescope Compact Array. These data provide information on the velocity, morphology and excitation parameters of the ionized gas associated with the two bright HII regions within the nebula, Car I and Car II. They are consistent with both Car I and Car II being expanding ionization fronts arising from the massive star clusters Trumpler 14 and Trumpler 16, respectively. The overall continuum emission distribution at 4.8 GHz is similar to that at lower frequencies. For Car I, two compact sources are revealed that are likely to be young HII regions associated with triggered star formation. These results provide the first evidence of ongoing star formation in the northern region of the nebula. A close association between Car I and the molecular gas is consistent with a scenario in which Car I is currently carving out a cavity within the northern molecular cloud. The complicated kinematics associated with Car II point to expansion from at least two different centres. All that is left of the molecular cloud in this region are clumps of dense gas and dust which are likely to be responsible for shaping the striking morphology of the Car II components., Comment: 10 pages, 7 figures, accepted for publication in MNRAS

We have made observations of the four hyperfine transitions of the 2Pi(3/2), J=3/2 ground state of OH at 1612, 1665, 1667 and 1720 MHz and the related 1.6-GHz continuum emission, towards NGC 6334 using the Australia Telescope Compact Array. The observations covered all the major radio continuum concentrations aligned along the axis of NGC 6334 (V, A to F). We have detected seven OH masers plus a possible faint eighth maser; two of these masers are located towards NGC 6334-A. Absorption at 1665 and 1667 MHz was detected towards almost all the continuum distribution. All transitions showed non-LTE behaviour. The 1667-/1665-MHz intensity ratios ranged from 1.0 to 1.2, significantly less than their LTE value of 1.8. The results of the OH `Sum Rule' suggest that this discrepancy cannot be explained solely by high optical depths. The 1612- and 1720-MHz line-profiles showed conjugate behaviour whereby one line was in absorption and the other in emission. In addition, the profiles commonly showed a flip from absorption to emission and vice versa, which has been interpreted as a density gradient. The OH line-to-continuum distribution, optical depth and velocity trends are consistent with a bar-like shape for the molecular gas which wraps around the continuum emission., Comment: 12 pages, 12 figures, accepted for publication in MNRAS

To better understand the environment surrounding CO emission clumps in the Keyhole Nebula, we have made images of the region in H2 1-0 S(1) (2.122 um) emission and polycyclic aromatic hydrocarbon (PAH) emission at 3.29 um. Our results show that the H2 and PAH emission regions are morphologically similar, existing as several clumps, all of which correspond to CO emission clumps and dark optical features. The emission confirms the existence of photodissociation regions (PDRs) on the surface of the clumps. By comparing the velocity range of the CO emission with the optical appearance of the H2 and PAH emission, we present a model of the Keyhole Nebula in which the most negative velocity clumps are in front of the ionization region, the clumps at intermediate velocities are in it, and those which have the least negative velocities are at the far side. It may be that these clumps, which appear to have been swept up from molecular gas by the stellar winds from eta Car, are now being over-run by the ionization region and forming PDRs on their surfaces. These clumps comprise the last remnants of the ambient molecular cloud around eta Car., Comment: 8 pages, 4 figures, to be published in MNRAS

The Carina Nebula is an extremely bright southern HII region embedded in a giant molecular cloud and contains some of the most massive stars known in our Galaxy. We are undertaking a multi-wavelength study of the Carina Nebula in order to examine the detailed kinematics and distribution of the molecular and ionised gas, and to look for further evidence of ongoing star formation. Here we present the results of the initial molecular cloud observations which were made by observing the 12CO(1-0) emission with the Mopra antenna. The observations reveal the clumpy morphology of the molecular gas, and allow us to identify many interesting regions for follow-up observations., Comment: Accepted by PASA; 9 pages, including 3 figures

We have carried out a series of observations of the 1665- and 1667-MHz transitions of the 2Pi_3/2, J=3/2 OH ground state towards six selected HII regions in the Large Magellanic Cloud (IRAS 05011-6815 and MRC 0510-689, 0513-694B, 0539-691, 0540-696B, 0540-697A) using the Australia Telescope Compact Array. The study has provided the first accurate positions for known 1665- and 1667-MHz OH masers as well as detecting several new masers. The regions all contain H_2O or CH_3OH masers but OH masers were detected in only four. The 1.6-GHz continuum emission was also imaged to investigate its spatial relationship to the associated OH maser. Although some masers are close to compact continuum components, in other cases they are near the continuum distribution boundaries and perhaps have been created as a result of the HII region interacting with the surrounding interstellar medium., Comment: Accepted for publication in MNRAS 6 pages, 9 figures