Results for "S. N. Longmore"

total 186619took 0.30s
Ks-band (2.14 micron) imaging of southern massive star formation regions traced by methanol masersJun 18 2009We present deep, wide-field, Ks-band (2.14 micron) images towards 87 southern massive star formation regions traced by methanol maser emission. Using point-spread function fitting, we generate 2.14 micron point source catalogues towards each of the regions. ... More
Embedded Stellar Populations towards Young Massive Star Formation Regions I. G305.2+0.2Jun 26 2007We present deep, wide-field J, H and Ks images taken with IRIS2 on the Anglo Australian Telescope, towards the massive star formation region G305.2+0.2. Combined with 3.6, 4.5, 5.8 and 8.0 micron data from the GLIMPSE survey on the Spitzer Space Telescope, ... More
Seeding the Galactic Centre gas stream: gravitational instabilities set the initial conditions for the formation of protocluster cloudsSep 06 2016Oct 05 2016Star formation within the Central Molecular Zone (CMZ) may be intimately linked to the orbital dynamics of the gas. Recent models suggest that star formation within the dust ridge molecular clouds (from G0.253+0.016 to Sgr B2) follows an evolutionary ... More
Hot high-mass accretion disk candidatesSep 03 2009To better understand the physical properties of accretion disks in high-mass star formation, we present a study of a 12 high-mass accretion disk candidates observed at high spatial resolution with the Australia Telescope Compact Array (ATCA) in the NH3 ... More
Seeding the Galactic Centre gas stream: gravitational instabilities set the initial conditions for the formation of protocluster cloudsSep 06 2016Star formation within the Central Molecular Zone (CMZ) may be intimately linked to the orbital dynamics of the gas. Recent models suggest that star formation within the dust ridge molecular clouds (from G0.253+0.016 to Sgr B2) follows an evolutionary ... More
Heart of Darkness: dust obscuration of the central stellar component in globular clusters younger than ~100Myr in multiple stellar population modelsJan 06 2015To explain the observed anomalies in stellar populations within globular clusters, many globular cluster formation theories require two independent episodes of star formation. A fundamental prediction of these models is that the clusters must accumulate ... More
Molecular gas in the inner 500pc of the MilkyWay: violating star formation relations and on the verge of forming extreme stellar clustersNov 06 2012With the HOPS, MALT90 and HiGAL Galactic plane surveys we are mapping a significant fraction of the dense, star-forming, molecular gas in the Galaxy. I present results from two projects based on this combined dataset, namely, (i) looking for variations ... More
New ammonia masers towards NGC6334INov 12 2007We 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" ... More
Too large and overlooked? Extended free-free emission towards massive star formation regionsJun 29 2009We present Australia Telescope Compact Array observations towards 6 massive star formation regions which, from their strong 24 GHz continuum emission but no compact 8 GHz continuum emission, appeared good candidates for hyper-compact HII regions. However, ... More
Ionization driven molecular outflow in K3-50AJul 03 2013Whether high mass stars continue to accrete material beyond the formation of an HII region is still an open question. Ionized infall and outflow have been seen in some sources, but their ties to the surrounding molecular gas are not well constrained. ... More
Mid-Infrared Source Multiplicity within Hot Molecular Cores traced by Methanol MasersApr 12 2006We present high resolution, mid-infrared images toward three hot molecular cores signposted by methanol maser emission; G173.49+2.42 (S231, S233IR), G188.95+0.89 (S252, AFGL-5180) and G192.60-0.05 (S255IR). Each of the cores was targeted with Michelle ... More
A search for High Mass Stars Forming in Isolation using CORNISH & ATLASGALNov 07 2015Theoretical models of high mass star formation lie between two extreme scenarios. At one extreme, all the mass comes from an initially gravitationally-bound core. At the other extreme, the majority of the mass comes from cluster scale gas, which lies ... More
SiO Outflow Signatures Toward Massive Young Stellar Objects with Linearly Distributed Methanol MasersOct 27 2008Methanol masers are often found in linear distributions, and it has been hypothesized that these masers are tracing circumstellar accretion disks around young massive stars. However, recent observations in H2 emission have shown what appear to be outflows ... More
The molecular environment of massive star forming cores associated with Class II methanol maser emissionApr 13 2007Methanol maser emission has proven to be an excellent signpost of regions undergoing massive star formation (MSF). To investigate their role as an evolutionary tracer, we have recently completed a large observing program with the ATCA to derive the dynamical ... More
Physical characterisation of southern massive star-forming regions using Parkes NH$_3$ observationsNov 23 2009We have undertaken a Parkes ammonia spectral line study, in the lowest two inversion transitions, of southern massive star formation regions, including young massive candidate protostars, with the aim of characterising the earliest stages of massive star ... More
Multi-wavelength observations of Southern Hot Molecular Cores traced by methanol masers - I. Ammonia and 24 GHz Continuum DataApr 17 2007We present observations of the (1,1), (2,2), (4,4) and (5,5) inversion transitions of para-ammonia (NH3) and 24 GHz continuum, taken with the Australia Telescope Compact Array toward 21 southern Galactic hot molecular cores traced by 6.7 GHz methanol ... More
Determining the relative evolutionary stages of very young massive star formation regionsNov 28 2007We have recently completed an observing program with the Australia Telescope Compact Array towards massive star formation regions traced by 6.7 GHz methanol maser emission. We found the molecular cores could be separated into groups based on their association ... More
Early Disc Accretion as the Origin of Abundance Anomalies in Globular ClustersSep 13 2013Globular clusters (GCs), once thought to be well approximated as simple stellar populations (i.e. all stars having the same age and chemical abundance), are now known to host a variety of anomalies, such as multiple discrete (or spreads in) populations ... More
The implications of clustered star formation for (proto)planetary systems and habitabilityJan 14 2019Star formation is spatially clustered across a range of environments, from dense stellar clusters to unbound associations. As a result, radiative or dynamical interactions with neighbouring stars disrupt (proto)planetary systems and limit their radii, ... More
An uncertainty principle for star formation. I. Why galactic star formation relations break down below a certain spatial scaleJan 17 2014Galactic scaling relations between the (surface densities of) the gas mass and the star formation (SF) rate are known to develop substantial scatter or even change form when considered below a certain spatial scale. We quantify how this behaviour should ... More
Comparing molecular gas across cosmic time-scales: the Milky Way as both a typical spiral galaxy and a high-redshift galaxy analogueSep 02 2013Detailed observations of the nearest star-forming regions in the Milky Way (MW) provide the ultimate benchmark for studying star formation. The extent to which the results of these Galaxy-based studies can be extrapolated to extragalactic systems depends ... More
Ionised gas kinematics in bipolar H II regionsMay 01 2018Stellar feedback plays a fundamental role in shaping the evolution of galaxies. Here we explore the use of ionised gas kinematics in young, bipolar H II regions as a probe of early feedback in these star-forming environments. We have undertaken a multiwavelength ... More
Physical and chemical conditions in methanol maser selected hot-cores and UCHII regionsDec 09 2008We present the results of a targeted 3-mm spectral line survey towards the eighty-three 6.67 GHz methanol maser selected star forming clumps observed by Purcell et al. 2006. In addition to the previously reported measurements of HCO+ (1 - 0), H13CO+ (1 ... More
Fragmentation and disk formation in high-mass star formation: The ALMA view of G351.77-0.54 at 0.06" resolutionMar 21 2017Aims: We resolve the small-scale structure around the high-mass hot core region G351.77-0.54 to investigate its disk and fragmentation properties. Methods: Using ALMA at 690GHz with baselines exceeding 1.5km, we study the dense gas, dust and outflow emission ... More
An uncertainty principle for star formation - II. A new method for characterising the cloud-scale physics of star formation and feedback across cosmic historyApr 30 2018Sep 04 2018The cloud-scale physics of star formation and feedback represent the main uncertainty in galaxy formation studies. Progress is hampered by the limited empirical constraints outside the restricted environment of the Local Group. In particular, the poorly-quantified ... More
Modes of star formation from HerschelNov 09 2012We summarize some of the results obtained from Herschel surveys of the nearby star forming regions and the Galactic plane. We show that in the nearby star forming regions the starless core spatial surface density distribution is very similar to that of ... More
An uncertainty principle for star formation - IV. On the nature and filtering of diffuse emissionOct 26 2018Diffuse emission is observed in galaxies in many tracers across the electromagnetic spectrum, including tracers of star formation, such as H$\alpha$ and ultraviolet (UV), and tracers of gas mass, such as carbon monoxide (CO) transition lines and the 21-cm ... More
Candidate super star cluster progenitor gas clouds possibly triggered by close passage to Sgr A*Apr 08 2013Super star clusters are the end product of star formation under the most extreme conditions. As such, studying how their final stellar populations are assembled from their natal progenitor gas clouds can provide strong constraints on star formation theories. ... More
Discovery of the new class I methanol maser transition at 23.4 GHzJan 05 2011We report the first detection of a methanol maser in the 10(1)-9(2)A- transition at 23.4 GHz, discovered during the H2O southern Galactic Plane Survey (HOPS) with the 22-m Mopra radio telescope. In the region covered by HOPS, the 23.4 GHz maser was found ... More
Comparing Young Massive Clusters and their Progenitor Clouds in the Milky WayFeb 08 2016Young massive clusters (YMCs) have central stellar mass surface densities exceeding $10^{4} M_{\odot} pc^{-2}$. It is currently unknown whether the stars formed at such high (proto)stellar densities. We compile a sample of gas clouds in the Galaxy which ... More
Tracing the Conversion of Gas into Stars in Young Massive Cluster ProgenitorsFeb 12 2015Whilst young massive clusters (YMCs; $M$ $\gtrsim$ 10$^{4}$ M$_{\odot}$, age $\lesssim$ 100 Myr) have been identified in significant numbers, their progenitor gas clouds have eluded detection. Recently, four extreme molecular clouds residing within 200 ... More
The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timelineDec 01 2014We recently proposed that the star-forming potential of dense molecular clouds in the Central Molecular Zone (CMZ, i.e. the central few 100 pc) of the Milky Way is linked to their orbital dynamics, potentially giving rise to an absolute-time sequence ... More
A survey for redshifted molecular and atomic absorption lines IJul 26 2006We are currently undertaking a large survey for redshifted atomic and molecular absorption ... only one clear and one tentative detection were obtained: HI absorption at z = 0.097 in PKS 1555-140 and OH absorption at z =0.126 in PKS 2300-189, respectively... ... More
Understanding hydrogen recombination line observations with ALMA and EVLAJun 29 2012Hydrogen recombination lines are one of the major diagnostics of H II region physical properties and kinematics. In the near future, the Expanded Very Large Array (EVLA) and the Atacama Large Millimeter Array (ALMA) will allow observers to study recombination ... More
Unveiling the Early-Stage Anatomy of a Protocluster Hub with ALMAJul 29 2016Sep 29 2016High-mass stars shape the interstellar medium in galaxies, and yet, largely because the initial conditions are poorly constrained, we do not know how they form. One possibility is that high-mass stars and star clusters form at the junction of filamentary ... More
Unveiling the Early-Stage Anatomy of a Protocluster Hub with ALMAJul 29 2016Aug 12 2016High-mass stars shape the interstellar medium in galaxies, and yet, largely because the initial conditions are poorly constrained, we do not know how they form. One possibility is that high-mass stars and star clusters form at the junction of filamentary ... More
Reproducible $k$-means clustering in galaxy feature data from the GAMA surveyOct 01 2018A fundamental bimodality of galaxies in the local Universe is apparent in many of the features used to describe them. Multiple sub-populations exist within this framework, each representing galaxies following distinct evolutionary pathways. Accurately ... More
An uncertainty principle for star formation - III. The characteristic emission time-scales of star formation rate tracersOct 25 2018We recently presented a new statistical method to constrain the physics of star formation and feedback on the cloud scale. Fundamentally, this new method is only able to recover the relative durations of different evolutionary phases. It therefore requires ... More
Investigating the structure and fragmentation of a highly filamentary IRDCJul 25 2016Aug 15 2016We present 3.7 arcsec (~0.05 pc) resolution 3.2 mm dust continuum observations from the IRAM PdBI, with the aim of studying the structure and fragmentation of the filamentary Infrared Dark Cloud G035.39-00.33. The continuum emission is segmented into ... More
Asymmetric Line Profiles in Dense Molecular Clumps Observed in MALT90: Evidence for Global CollapseNov 13 2018Using molecular line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90), we have searched the optically thick \hcop\, line for the "blue asymmetry" spectroscopic signature of infall motion in a large sample of high-mass, dense molecular ... More
Multi-generation massive star-formation in NGC3576Sep 07 2009Recent 1.2-mm continuum observations have shown the giant HII region NGC3576 to be embedded in the centre of an extended filamentary dust-cloud. The bulk of the filament away from the HII region contains a number of clumps seen only at (sub-)millimetre ... More
High-mass star formation at sub-50AU scalesNov 26 2018Methods: We observed the high-mass hot core region G351.77-0.54 with ALMA and more than 16km baselines. Results: At a spatial resolution of 18/40au (depending on the distance), we identify twelve sub-structures within the inner few thousand au of the ... More
Constraining globular cluster formation through studies of young massive clusters - V. ALMA observations of clusters in the AntennaeJan 22 2015Some formation scenarios that have been put forward to explain multiple populations within Globular Clusters (GCs) require that the young massive cluster have large reservoirs of cold gas within them, which is necessary to form future generations of stars. ... More
Variations in the Galactic star formation rate and density thresholds for star formationAug 21 2012The conversion of gas into stars is a fundamental process in astrophysics and cosmology. Stars are known to form from the gravitational collapse of dense clumps in interstellar molecular clouds, and it has been proposed that the resulting star formation ... More
A cluster in the making: ALMA reveals the initial conditions for high-mass cluster formationJan 29 2015G0.253+0.016 is a molecular clump that appears to be on the verge of forming a high mass, Arches-like cluster. Here we present new ALMA observations of its small-scale (~0.07 pc) 3mm dust continuum and molecular line emission. The data reveal a complex ... More
Molecular line mapping of the giant molecular cloud associated with RCW 106 - II. Column density and dynamical state of the clumpsFeb 15 2008We present a fully sampled C^{18}O (1-0) map towards the southern giant molecular cloud (GMC) associated with the HII region RCW 106, and use it in combination with previous ^{13}CO (1-0) mapping to estimate the gas column density as a function of position ... More
G0.253+0.016: A centrally condensed, high-mass protoclusterMar 05 2014Despite their importance as stellar nurseries and the building blocks of galaxies, very little is known about the formation of the highest mass clusters. The dense clump G0.253+0.016 represents an example of a clump that may form an Arches-like, high-mass ... More
Turbulence sets the initial conditions for star formation in high-pressure environmentsSep 03 2014Despite the simplicity of theoretical models of supersonically turbulent, isothermal media, their predictions successfully match the observed gas structure and star formation activity within low-pressure (P/k < 10^5 K cm^-3) molecular clouds in the solar ... More
VLASSICK: The VLA Sky Survey in the Central KiloparsecJan 15 2014At a distance of 8 kpc, the center of our Galaxy is the nearest galactic nucleus, and has been the subject of numerous key projects undertaken by great observatories such as Chandra, Spitzer, and Herschel. However, there are still no surveys of molecular ... More
ALMA Compact Array observations of the Fried Egg nebula: Evidence for large-scale asymmetric mass-loss from the yellow hypergiant IRAS 17163-3907Dec 08 2016Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA Compact Array observations ... More
The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016Sep 19 2016Star formation is primarily controlled by the interplay between gravity, turbulence, and magnetic fields. However, the turbulence and magnetic fields in molecular clouds near the Galactic Center may differ substantially from spiral-arm clouds. Here we ... More
The link between solenoidal turbulence and slow star formation in G0.253+0.016Sep 28 2016Star formation in the Galactic disc is primarily controlled by gravity, turbulence, and magnetic fields. It is not clear that this also applies to star formation near the Galactic Centre. Here we determine the turbulence and star formation in the CMZ ... More
Absorption Filaments Towards the Massive Clump G0.253+0.016Sep 12 2014ALMA HCO+ observations of the infrared dark cloud G0.253+0.016 located in the Central Molecular Zone of the Galaxy are presented. The 89 GHz emission is area-filling, optically thick, and sub-thermally excited. Two types of filaments are seen in absorption ... More
Star and Stellar Cluster Formation: ALMA-SKA SynergiesApr 14 2015Over the next decade, observations conducted with ALMA and the SKA will reveal the process of mass assembly and accretion onto young stars and will be revolutionary for studies of star formation. Here we summarise the capabilities of ALMA and discuss ... More
Is protostellar heating sufficient to halt fragmentation? A case study of the massive protocluster G8.68-0.37Nov 05 2010If star formation proceeds by thermal fragmentation and the subsequent gravitational collapse of the individual fragments, how is it possible to form fragments massive enough for O and B stars in a typical star-forming molecular cloud where the Jeans ... More
OH absorption in the first quadrant of the Milky Way as seen by THORMar 13 2018Sep 16 2018The hydroxyl radical (OH) is present in the diffuse molecular and partially atomic phases of the interstellar medium (ISM), but its abundance relative to hydrogen is not clear. We aim to evaluate the abundance of OH with respect to molecular hydrogen ... More
The Millimeter Astronomy Legacy Team 90 GHz Survey (MALT90) and ALMAMar 12 2013ALMA will revolutionize our understanding of star formation within our galaxy, but before we can use ALMA we need to know where to look. The Millimeter Astronomy Legacy Team 90 GHz (MALT90) Survey is a large international project to map the molecular ... More
Astro2020 Science White Paper: What is the lifecycle of gas and stars in galaxy centers?Mar 11 2019The closest galaxy center, our own Central Molecular Zone (CMZ; the central 500 pc of the Milky Way), is a powerful laboratory for studying the secular processes that shape galaxies across cosmic time, from large-scale gas flows and star formation to ... More
Radio continuum emission in the northern Galactic plane: Sources and spectral indices from the THOR surveyAug 17 2018Aug 21 2018Radio continuum surveys of the Galactic plane can find and characterize HII regions, supernova remnants (SNRs), planetary nebulae (PNe), and extragalactic sources. A number of surveys at high angular resolution (<25") at different wavelengths exist to ... More
Galactic Supernova Remnant Candidates Discovered by THORMay 31 2017There is a considerable deficiency in the number of known supernova remnants (SNRs) in the Galaxy compared to that expected. Searches for extended low-surface brightness radio sources may find new Galactic SNRs, but confusion with the much larger population ... More
Continuum sources from the THOR survey between 1 and 2 GHzJan 13 2016We carried out a large program with the Karl G. Jansky Very Large Array (VLA): "THOR: The HI, OH, Recombination line survey of the Milky Way". We observed a significant portion of the Galactic plane in the first quadrant of the Milky Way in the 21cm HI ... More
The H2O southern Galactic Plane Survey(HOPS): NH3 (1,1) and (2,2) cataloguesJul 26 2012The 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 ... More
Molecules at z=0.89: A 4-mm-rest-frame absorption line survey toward PKS 1830-211Apr 18 2011Sep 20 2011We present the results of a 7 mm spectral survey of molecular absorption lines originating in the disk of a z=0.89 spiral galaxy located in front of the quasar PKS 1830-211. [...] A total of 28 different species, plus 8 isotopic variants, were detected ... More
The H_2O southern Galactic Plane Survey (HOPS): I. Techniques and H_2O maser dataMay 24 2011We 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), ... More
The dynamical evolution of molecular clouds near the Galactic Centre - II. Spatial structure and kinematics of simulated cloudsFeb 05 2019Feb 07 2019The evolution of molecular clouds in galactic centres is thought to differ from that in galactic discs due to a significant influence of the external gravitational potential. We present a set of numerical simulations of molecular clouds orbiting on the ... More
CHIMPS: the $^{13}$CO/C$^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane SurveyDec 27 2015We present the $^{13}$CO/C$^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral ... More
The VLT-FLAMES Tarantula Survey IV: Candidates for isolated high-mass star formation in 30 DoradusApr 16 2012Apr 18 2012Whether massive stars can occasionally form in relative isolation or if they require a large cluster of lower-mass stars around them is a key test in the differentiation of star formation theories as well as how the initial mass function of stars is sampled. ... More
ALMA survey of massive cluster progenitors from ATLASGAL. Limited fragmentation at the early evolutionary stage of massive clumpsMar 09 2017The early evolution of massive cluster progenitors is poorly understood. We investigate the fragmentation properties from 0.3 pc to 0.06 pc scales of a homogenous sample of infrared-quiet massive clumps within 4.5 kpc selected from the ATLASGAL survey. ... More
The HI/OH/Recombination line survey of the inner Milky Way (THOR)Sep 12 2016Context: The past decade has witnessed a large number of Galactic plane surveys at angular resolutions below 20". However, no comparable high-resolution survey exists at long radio wavelengths around 21cm in line and continuum emission. Methods: Employing ... More
What controls star formation in the central 500 pc of the Galaxy?Mar 25 2013Mar 12 2014The star formation rate (SFR) in the Central Molecular Zone (CMZ, i.e. the central 500 pc) of the Milky Way is lower by a factor of >10 than expected for the substantial amount of dense gas it contains, which challenges current star formation theories. ... More
'The Brick' is not a brick: A comprehensive study of the structure and dynamics of the Central Molecular Zone cloud G0.253+0.016Feb 07 2019In this paper we provide a comprehensive description of the internal dynamics of G0.253+0.016 (a.k.a. 'the Brick'); one of the most massive and dense molecular clouds in the Galaxy to lack signatures of widespread star formation. As a potential host to ... More
The first Galaxy scale hunt for the youngest high-mass protostarsDec 13 2015The origin of massive stars is a fundamental open issue in modern astrophysics. Pre-ALMA interferometric studies reveal precursors to early B to late O type stars with collapsing envelopes of 15-20 M$_\odot$ on 1000-3000 AU size-scales. To search for ... More
Addressing environmental and atmospheric challenges for capturing high-precision thermal infrared data in the field of astro-ecologyJul 06 2018Using thermal infrared detectors mounted on drones, and applying techniques from astrophysics, we hope to support the field of conservation ecology by creating an automated pipeline for the detection and identification of certain endangered species and ... More
Deeply Embedded Protostellar Population in the Central Molecular Zone Suggested by H$_2$O Masers and Dense CoresSep 27 2016The Central Molecular Zone (CMZ), usually referring to the inner 500 pc of the Galaxy, contains a dozen of massive ($\sim10^5$ $M_\odot$) molecular clouds. Are these clouds going to actively form stars like Sgr B2? How are they affected by the extreme ... More
VLT-MAD observations of the core of 30 DoradusFeb 01 2010Mar 01 2010We present H- and Ks-band imaging of three fields at the centre of 30 Doradus in the Large Magellanic Cloud, obtained as part of the Science Demonstration programme with the Multi-conjugate Adaptive optics Demonstrator (MAD) at the Very Large Telescope. ... More
Excitation Conditions in the Multi-component Submillimeter Galaxy SMM J00266+1708Nov 03 2014We present multiline CO observations of the complex submillimeter galaxy SMM J00266+1708. Using the Zpectrometer on the Green Bank Telescope, we provide the first precise spectroscopic measurement of its redshift (z=2.742). Based on followup CO(1-0), ... More
Deeply Embedded Protostellar Population in the 20 km s-1 Cloud of the Central Molecular ZoneOct 16 2015We report the discovery of a population of deeply embedded protostellar candidates in the 20 km s$^{-1}$ cloud, one of the massive molecular clouds in the Central Molecular Zone (CMZ) of the Milky Way, using interferometric submillimeter continuum and ... More
Histogram of oriented gradients: a technique for the study of molecular cloud formationSep 21 2018Jan 02 2019We introduce the histogram of oriented gradients (HOG), a tool developed for machine vision that we propose as a new metric for the systematic characterization of observations of atomic and molecular gas and the study of molecular cloud formation models. ... More
Molecular gas kinematics within the central 250 pc of the Milky WayJan 14 2016Feb 10 2016Using spectral-line observations of HNCO, N2H+, and HNC, we investigate the kinematics of dense gas in the central ~250 pc of the Galaxy. We present SCOUSE (Semi-automated multi-COmponent Universal Spectral-line fitting Engine), a line fitting algorithm ... More
12mm line survey of the dense molecular gas towards the W28 field TeV gamma-ray sourcesSep 24 2010We present 12mm Mopra observations of dense molecular gas towards the W28 supernova remnant (SNR) field. The focus is on the dense molecular gas towards the TeV gamma-ray sources detected by the H.E.S.S. telescopes, which likely trace the cosmic-rays ... More
High-mass star formation in the Southern Hemisphere skyDec 02 2004We report on a multi-wavelength (IR to cm) and multi-resolution (1 mas to 20 arcsec) exploration of high-mass star formation regions in the Galactic plane, at longitudes observable from the Southern Hemisphere. Our source sample was originally identified ... More
Star formation in a high-pressure environment: An SMA view of the Galactic centre dust ridgeNov 02 2017The star formation rate in the Central Molecular Zone (CMZ) is an order of magnitude lower than predicted according to star formation relations that have been calibrated in the disc of our own and nearby galaxies. Understanding how and why star formation ... More
Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular cloudsMar 14 2019Young massive clusters (YMCs) are the most compact, high-mass stellar systems still forming at the present day. The precursor clouds to such systems are, however, rare due to their large initial gas mass reservoirs and rapid dispersal timescales due to ... More
Star-forming protoclusters associated with methanol masersNov 26 2004We present a multiwavelength study of five methanol maser sites which are not directly associated with a strong ($>100$ mJy) radio continuum source: G 31.28+0.06, G 59.78+0.06, G 173.49+2.42 (S231, S233IR), G 188.95+0.89 (S252, AFGL5180) and G 192.60-0.05 ... More
MALT-45: A 7 mm survey of the southern Galaxy - I. Techniques and spectral line dataJan 27 2015Feb 01 2015We present the first results from the MALT-45 (Millimetre Astronomer's Legacy Team - 45 GHz) Galactic Plane survey. We have observed 5 square-degrees ($l = 330 - 335$, $b = \pm0.5$) for spectral lines in the 7 mm band (42-44 and 48-49 GHz), including ... More
A Survey for Hydroxyl in the THOR Pilot Region around W43Oct 21 2015We report on observations of the hydroxyl radical (OH) within The H{\sc I}, OH Recombination line survey (THOR) pilot region. The region is bounded approximately between Galactic coordinates l=29.2 to 31.5$^\circ$ and b=-1.0 to +1.0$^\circ$ and includes ... More
Core fragmentation and Toomre stability analysis of W3(H2O): A case study of the IRAM NOEMA large program COREAug 01 2018The fragmentation mode of high-mass molecular clumps and the properties of the central rotating structures surrounding the most luminous objects have yet to be comprehensively characterised. Using the IRAM NOrthern Extended Millimeter Array (NOEMA) and ... More
The UKIDSS Galactic Plane SurveyDec 01 2007Sep 26 2008The UKIDSS Galactic Plane Survey (GPS) is one of the five near infrared Public Legacy Surveys that are being undertaken by the UKIDSS consortium, using the Wide Field Camera on the United Kingdom Infrared Telescope. It is surveying 1868 sq.deg. of the ... More
Fragmentation and disk formation during high-mass star formation: The IRAM NOEMA (Northern Extended Millimeter Array) large program COREMay 03 2018Aims: We aim to understand the fragmentation as well as the disk formation, outflow generation and chemical processes during high-mass star formation on spatial scales of individual cores. Methods: Using the IRAM Northern Extended Millimeter Array (NOEMA) ... More
Science Programs for a 2 m-class Telescope at Dome C, Antarctica: PILOT, the Pathfinder for an International Large Optical TelescopeNov 22 2004Apr 29 2005The cold, dry and stable air above the summits of the Antarctic plateau provides the best ground-based observing conditions from optical to sub-mm wavelengths to be found on the Earth. PILOT is a proposed 2 m telescope, to be built at Dome C in Antarctica, ... More
THOR - The HI, OH, Recombination Line Survey of the Milky Way - The pilot study: HI observations of the giant molecular cloud W43May 19 2015To study the atomic, molecular and ionized emission of Giant Molecular Clouds (GMCs), we have initiated a Large Program with the VLA: 'THOR - The HI, OH, Recombination Line survey of the Milky Way'. We map the 21cm HI line, 4 OH lines, 19 H_alpha recombination ... More
Star Formation Rates of Massive Molecular Clouds in the Central Molecular ZoneJan 23 2019We investigate star formation at very early evolutionary phases in five massive clouds in the inner 500 pc of the Galaxy, the Central Molecular Zone. Using interferometer observations of H$_2$O masers and ultra-compact H II regions, we find evidence of ... More
The Formation and Early Evolution of Young Massive ClustersJan 16 2014We review the formation and early evolution of the most massive and dense young stellar clusters, focusing on the role they can play in our understanding of star and planet formation as a whole. Young massive cluster (YMC) progenitor clouds in the Galactic ... More
Star Formation Rates of Massive Molecular Clouds in the Central Molecular ZoneJan 23 2019Feb 21 2019We investigate star formation at very early evolutionary phases in five massive clouds in the inner 500 pc of the Galaxy, the Central Molecular Zone. Using interferometer observations of H$_2$O masers and ultra-compact H II regions, we find evidence of ... More
Accurate water maser positions from HOPSMay 16 2014We report on high spatial resolution water maser observations, using the Australia Telescope Compact Array, towards water maser sites previously identified in the H2O southern Galactic Plane Survey (HOPS). Of the 540 masers identified in the single-dish ... More
A Pilot Survey for the H$_2$O Southern Galactic Plane Survey (HOPS)Apr 25 2008We describe observations with the Mopra radiotelescope designed to assess the feasibility of the H$_2$O maser southern Galactic plane survey (HOPS). We mapped two one-square-degree regions along the Galactic plane using the new 12 mm receiver and the ... More
Characterization of the MALT90 Survey and the Mopra Telescope at 90 GHzJun 03 2013Jul 09 2013We characterize the Millimeter Astronomy Legacy Team 90 GHz (MALT90) Survey and the Mopra telescope at 90 GHz. We combine repeated position-switched observations of the source G300.968+01.145 with a map of the same source in order to estimate the pointing ... More
A CH3CN and HCO+ survey towards southern methanol masers associated with star formationDec 23 2005We present the initial results of a 3-mm spectral line survey towards 83 methanol maser selected massive star-forming regions. Here we report observations of the J=5-4 and 6-5 rotational transitions of methyl cyanide (CH3CN) and the J=1-0 transition of ... More
The JCMT Plane Survey: First complete data release - emission maps and compact source catalogueApr 10 2017We present the first data release of the James Clerk Maxwell Telescope (JCMT) Plane Survey (JPS), the JPS Public Release 1 (JPSPR1). JPS is an 850-um continuum survey of six fields in the northern inner Galactic Plane in a longitude range of l=7-63, made ... More
G0.253+0.016: a molecular cloud progenitor of an Arches-like clusterNov 14 2011Young massive clusters (YMCs) with stellar masses of 10^4 - 10^5 Msun and core stellar densities of 10^4 - 10^5 stars per cubic pc are thought to be the `missing link' between open clusters and extreme extragalactic super star clusters and globular clusters. ... More