A5033369192- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Atmospheric Ozone and Climate
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Molecular Spectroscopy and Structure
- Gamma-ray bursts and supernovae
- Spectroscopy and Laser Applications
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Spacecraft and Cryogenic Technologies
- Advanced Combustion Engine Technologies
- Advanced Chemical Physics Studies
- Catalysis and Oxidation Reactions
- Atomic and Molecular Physics
- Atmospheric and Environmental Gas Dynamics
- Pulsars and Gravitational Waves Research
- Computational Physics and Python Applications
- Advanced Data Processing Techniques
- Superconducting and THz Device Technology
- Fractal and DNA sequence analysis
- Gaussian Processes and Bayesian Inference
Australia Telescope National Facility
2014-2024
Commonwealth Scientific and Industrial Research Organisation
2014-2024
Astronomy and Space
2011-2024
Macquarie University
2015-2024
Astronomy Australia
2022
University of Tasmania
2011-2014
Nagoya University
2006-2012
Rutherford Appleton Laboratory
2009
University of Sheffield
2009
University of Oxford
2009
We have made CO(J = 2–1) observations toward the H ii region RCW 49 and its ionizing source, rich stellar cluster Westerlund 2, with NANTEN2 submillimeter telescope. These revealed that two molecular clouds in velocity ranges of −11 to +9 km s−1 11 21 s−1, respectively, show remarkably good spatial correlations Spitzer IRAC mid-infrared image 49, as well a structures indicative localized expansion around bright central regions cluster. This strongly suggests are physically associated 49....
We present new large field observations of molecular clouds with NANTEN2 toward the super star cluster NGC 3603 in transitions 12CO(J = 2–1, J 1–0) and 13CO(J 1–0). suggest that two at 13 km s−1 28 are associated as evidenced by higher temperatures H ii region, well morphological correspondence. The mass is too small to gravitationally bind them, given their relative motion ∼20 s−1. collided each other 1 Myr ago trigger formation cluster. This scenario able explain origin highest stellar...
Recently, a comparison between the locations of 6.7-GHz methanol masers and dust continuum emission has renewed speculation that these can be associated with evolved stars. The implication such scenario would profound, especially for interpretation large surveys masers, individual studies where high-mass star formation been inferred from presence pumping mechanisms masers. We have investigated two instances explicitly suggested to stars, we find first standard region, second spurious...
ABSTRACT We present distributions of two molecular clouds having velocities 2 and 14 km s −1 toward RCW 38, the youngest super star cluster in Milky Way, 12 CO J = 1–0 3–2 13 transitions. The are likely physically associated with as verified by high intensity ratio emission to emission, bridging feature connecting velocity, their morphological correspondence infrared dust emission. velocity difference is too large for be gravitationally bound. frame a hypothesis that colliding each other...
A large-scale study of the molecular clouds toward Trifid Nebula, M20, has been made in J = 2–1 and 1–0 transitions 12CO 13CO. M20 is ionized predominantly by an O7.5 star HD164492. The revealed that there are two components at separate velocities peaked center their temperatures—30–50 K as derived a large velocity gradient analysis—are significantly higher than 10 surroundings. We identify parent first generation stars M20. mass each cloud estimated to be ∼103 M☉ separation ∼8 km s−1 over...
Furukawa et al. reported the existence of a large mass molecular gas associated with super star cluster Westerlund 2 and surrounding H ii region RCW49, based on strong morphological correspondence between NANTEN2 12CO(J = 2–1) emission Spitzer IRAC images region. We here present temperature density distributions in at ∼3.5 pc resolution, as derived from velocity gradient analysis 2–1), 1–0), 13CO(J transitions. The kinetic is high ∼60–150 K within projected distance ∼5–10 decreases to low...
A survey of the Milky Way disk and Magellanic System at wavelengths 21-cm atomic hydrogen (HI) line three 18-cm lines OH molecule will be carried out with Australian Square Kilometre Array Pathfinder telescope. The study distribution HI emission absorption unprecedented angular velocity resolution, as well molecular thermal emission, absorption, maser lines. area to covered includes Galactic plane (|b|< 10deg) all declinations south delta = +40deg, spanning longitudes 167deg through 360deg...
We describe an ultra-wide-bandwidth, low-frequency receiver ("UWL") recently installed on the Parkes radio telescope. The system provides continuous frequency coverage from 704 to 4032 MHz. For much of band (~60%) temperature is approximately 22K and remains in a linear regime even presence strong mobile phone transmissions. discuss scientific technical aspects new including its astronomical objectives, as well feed, receiver, digitiser signal-processor design. pipeline routines that form...
We investigate the influence of large-scale stellar feedback on formation molecular clouds in Large Magellanic Cloud (LMC). Examining relationship between HI and 12CO(J=1-0) supergiant shells (SGSs), we find that fraction total volume occupied by SGSs is not enhanced with respect to rest LMC disk. However, majority objects (~70% mass) are more than their local surroundings, implying presence a shell does average have positive effect gas fraction. Averaged over full SGS sample, our results...
We present the most sensitive and detailed view of neutral hydrogen (HI) emission associated with Small Magellanic Cloud (SMC), through combination data from Australian Square Kilometre Array Pathfinder (ASKAP) Parkes (Murriyang), as part Galactic (GASKAP) pilot survey. These GASKAP-HI observations, for first time, reveal HI in SMC on similar physical scales other important tracers interstellar medium, such molecular gas dust. The resultant image cube possesses an rms noise level 1.1 K (1.6...
Pulsar timing array collaborations have recently reported evidence for a noise process with common spectrum among the millisecond pulsars in arrays. The spectral properties of this common-noise are consistent expectations an isotropic gravitational-wave background (GWB) from inspiralling supermassive black-hole binaries. However, recent simulation analyses based on Parkes Timing Array data indicate that such detection may arise spuriously. In paper, we use simulated pulsar datasets to...
SPLASH (the Southern Parkes Large-Area Survey in Hydroxyl) is a sensitive, unbiased and fully-sampled survey of the Galactic Plane Centre all four ground-state transitions hydroxyl (OH) radical. The provides deep census 1612-, 1665-, 1667- 1720-MHz OH absorption emission from ISM, also an search for maser sources these transitions. We present here first results pilot region, which covers longitudes 334 to 344 degrees latitudes -2 +2 degrees. Diffuse widely detected transitions, with optical...
ABSTRACT We present the largest Galactic neutral hydrogen H i absorption survey to date, utilizing Australian SKA Pathfinder Telescope at an unprecedented spatial resolution of 30 arcsec. This survey, GASKAP-H i, unbiasedly targets 2714 continuum background sources over 250 square degrees in direction Magellanic Clouds, a significant increase compared total 373 observed by previous surveys across entire Milky Way. aim investigate physical properties cold (CNM) and warm (WNM) atomic gas Way...
We present parsec-scale resolution observations of the atomic and molecular ISM in two Galactic supershells, GSH 287+04-17 277+00+36. HI synthesis images from Australia Telescope Compact Array are combined with 12CO(J=1-0) data NANTEN telescope to reveal substantial quantities gas closely associated both shells. These allow us confirm an enhanced level molecularization over volumes objects, providing first direct observational evidence increased cloud production due influence supershells....
Abstract We investigated H i absorption toward a single pulsar, PSR J1644−4559, and its variability over timescales from days to years, using Murriyang, CSIRO’s Parkes Radio Telescope. Our 19 epochs of spectral observations, spanning 1.2 yr with intervals as short 1 day, provide the most comprehensive cadence coverage for monitoring date. identified two significant detections tiny-scale atomic structure (TSAS) spatial scales ranging lower limit ∼11 au an upper 165 au, both exhibiting...
Abstract Observations of interstellar dust are often used as a proxy for total gas column density N H . By comparing Planck thermal data (Release 1.2) and new reddening maps from Pan-STARRS 1 2MASS, with accurate (opacity-corrected) i densities newly published OH the Arecibo Millennium survey 21-SPONGE, we confirm linear correlations between optical depth τ 353 , E ( B − V ), proton in range (1–30) × 10 20 cm −2 along sightlines no molecular detections emission. We derive an / ) ratio (9.4 ±...
We have conducted the first parallax and proper motion measurements of 6.7 GHz methanol maser emission using Australian Long Baseline Array (LBA). The G339.884$-$1.259 measured from five epochs observations is 0.48$\pm $0.08 mas, corresponding to a distance $2.1^{+0.4}_{-0.3}$ kpc, placing it in Scutum spiral arm. This consistent (within combined uncertainty) with kinematic estimate for this source at 2.5$\pm $0.5 kpc latest Solar Galactic rotation parameters. find Lyman continuum photon...
Abstract We report Arecibo 21 cm absorption-emission observations to characterize the physical properties of neutral hydrogen (H i ) in proximity five giant molecular clouds (GMCs): Taurus, California, Rosette, Mon OB1, and NGC 2264. Strong H absorption was detected toward all 79 background-continuum sources ∼60 × 20 square degree region. Gaussian decompositions were performed estimate temperatures, optical depths, column densities cold warm medium (CNM WNM). The individual CNM components...
Abstract Using the Australian Square Kilometre Array Pathfinder to measure 21 cm absorption spectra toward continuum background sources, we study cool phase of neutral atomic gas in far outer disk, and inner Galaxy near end Galactic bar at longitude 340°. In Galaxy, has a smaller scale height than solar neighborhood, similar molecular super-thin stellar population bar. is mixed with warm, medium, fraction staying roughly constant radius. The ratio emission brightness temperature absorption,...
We have discovered a new H$_2$CO (formaldehyde) $1_{1,0}-1_{1,1}$ 4.82966 GHz maser in Galactic Center Cloud C, G0.38+0.04. At the time of acceptance, this is eighth region containing an detected Galaxy. C one only two sites confirmed high-mass star formation along Ridge, affirming that masers are exclusively associated with formation. This discovery led us to search for other masers, among which we found SiO vibrationally excited making fourth star-forming Galaxy exhibit emission. also...
Dense, star-forming gas is believed to form at the stagnation points of large-scale interstellar medium flows, but observational examples this process in action are rare. We here present a giant molecular cloud (GMC) sandwiched between two colliding Milky Way supershells, which we argue shows strong evidence having formed from material accumulated collision zone. Combining 12CO, 13CO, and C18O(J = 1–0) data with new high-resolution, three-dimensional hydrodynamical simulations discuss origin...
Hydroxyl (OH) is expected to be abundant in diffuse interstellar molecular gas as it forms along with $H_2$ under similar conditions and within a extinction range. We have analyzed absorption measurements of OH at 1665 MHz 1667 toward 44 extragalactic continuum sources, together the J=1-0 transitions $^{12}$CO, $^{13}$CO , C$^{18}$O, J=2-1 $^{12}$CO. The excitation temperature were found follow modified log-normal distribution, $ f(T{\rm_{ex}}) \propto \frac{1}{ \sqrt{2\pi}\sigma }...
ABSTRACT We report on OH maser emission toward G336.644−0.695 (IRAS 16333−4807), which is a H 2 O maser-emitting Planetary Nebula (PN). have detected 1612, 1667, and 1720 MHz masers at two epochs using the Australia Telescope Compact Array, hereby confirming it as seventh known case of an OH-maser-emitting PN. This only second PN showing after K 3−35 evolved stellar object with strongest transition. one group very young PNe. The 1612 1667 are similar velocity to 22 GHz masers, whereas show...
Large-scale shocks formed by clustered feedback of young OB stars are considered an important source mechanical energy for the ISM and a trigger molecular cloud formation. Their interaction sites locations where kinetic magnetic fields redistributed between phases. In this work we study effect field on expansion fragmentation supershells look signatures supershell collisions dense structures distribution ISM. We performed series high-resolution, three-dimensional simulations colliding...
HI self absorption (HISA) clouds are clumps of cold neutral hydrogen (HI) visible in front warm background gas, which makes them ideal places to study the properties atomic component interstellar medium (ISM). The Riegel-Crutcher (R-C) cloud is most striking HISA feature Galaxy. It one closest us and located direction Galactic Centre, provides a bright background. High-resolution interferometric measurements have revealed filamentary structure this cloud, however it difficult accurately...