A5010603271- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Adaptive optics and wavefront sensing
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Molecular Spectroscopy and Structure
- Scientific Research and Discoveries
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Spectroscopy and Laser Applications
- Geophysics and Gravity Measurements
- Pulsars and Gravitational Waves Research
- Space Exploration and Technology
- Astronomical and nuclear sciences
- Historical Astronomy and Related Studies
- Atomic and Subatomic Physics Research
- Electromagnetic Compatibility and Noise Suppression
- Atmospheric Ozone and Climate
University of Manchester
2015-2024
Macquarie University
2024
University of Hong Kong
2017-2023
Cyberport
2018-2023
SKA Observatory
2011-2021
RMIT University
2021
The Open University
2021
International Islamic University Malaysia
2021
Institute of Astronomy
2021
KU Leuven
2007-2019
The INT Photometric Halpha Survey of the Northern Galactic Plane (IPHAS) is a 1800 square degrees CCD survey northern Milky Way spanning latitude range -5 < b +5 (degrees) and reaching down to r' ~ 20 (10-sigma). It may increase number known emission line sources by an order magnitude. Representative observations assessment point-source data from IPHAS, now underway, are presented. obtained Wide Field Camera images in narrow-band, Sloan i' broad-band, filters. We simulate IPHAS (r' -...
We present an empirical determination of the mass-loss rate as a function stellar luminosity and effective temperature, for oxygen-rich dust-enshrouded Asymptotic Giant Branch stars red supergiants. To this aim we obtained optical spectra sample giants in Large Magellanic Cloud, which complemented with spectroscopic infrared photometric data from literature. Two these turned out to be hot emission-line stars, one is definite B[e] star. The rates were measured through modelling spectral...
We derive the fundamental parameters (temperature and luminosity) of 107 619 Hipparcos stars place these on a true Hertzsprung–Russell diagram. This is achieved by comparing bt-settl model atmospheres to spectral energy distributions (SEDs) created from Hipparcos, Tycho, Sloan Digital Sky Survey, DENIS, Two Micron All MSX, AKARI, IRAS Wide-field Infrared Survey Explorer data. also identify quantify SEDs any infrared excesses attributable circumstellar matter. compare our results known types...
The VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying southern Milky Way in u, g, r, i at 1 arcsec angular resolution. Its footprint spans latitude range -5 < b +5 all longitudes south celestial equator. Extensions around Centre to latitudes +/-10 bring much Bulge. This ESO public survey, begun on 28th December 2011, reaches down 20th magnitude (10-sigma) will provide single-epoch digital optical photometry for 300 million stars. observing strategy...
We report on an analysis of the gas and dust budget in interstellar medium (ISM) Large Magellanic Cloud (LMC). Recent observations from Spitzer Space Telescope enable us to study mid-infrared excess asymptotic giant branch (AGB) stars LMC. This is first time we can quantitatively assess input AGB over a complete galaxy, fully based observations. The integrated mass-loss rate all intermediate high carbon-rich candidates LMC 8.5x10^-3 solar mass per year, up 2.1x10^-2 year. number could be...
We present late-time optical and mid-infrared observations of the Type II supernova 2003gd in galaxy NGC 628. Mid-infrared excesses consistent with cooling dust ejecta are observed 499 to 678 days after outburst accompanied by increasing extinction growing asymmetries emission-line profiles. Radiative-transfer models show that up 0.02 solar masses has formed within ejecta, beginning as early 250 outburst. These formation can be efficient massive-star supernovae could have been major...
The CORNISH project is the highest resolution radio continuum survey of Galactic plane to date. It 5 GHz part a series multi-wavelength surveys that focus on northern GLIMPSE region (10 deg < l 65 deg), observed by Spitzer satellite in mid-infrared. Observations with Very Large Array B and BnA configurations have yielded 1.5" Stokes I map root-mean-squared noise level better than 0.4 mJy/beam. Here we describe data-processing methods data characteristics, present new, uniform catalogue...
The INT/WFC Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS) is a 1800 square degrees imaging survey covering latitudes |b| < 5 deg and longitudes l = 30 to 215 in r, i H-alpha filters using Wide Field Camera (WFC) on 2.5-metre Isaac Newton Telescope (INT) La Palma. We present first quality-controlled globally-calibrated source catalogue derived from survey, providing single-epoch photometry for 219 million unique sources across 92% footprint. observations were carried out...
We describe the motivation, design, and implementation of CORNISH survey, an arcsecond-resolution radio continuum survey inner galactic plane at 5 GHz using Very Large Array (VLA). It is a blind coordinated with northern Spitzer GLIMPSE I region covering 10° < l 65° |b| 1° similar resolution. discuss in detail strategy that we employed to control shape synthesised beam across this which covers wide range fairly low declinations. Two snapshots separated by 4h kept elongation less 1.5 over 75%...
We present the results of our survey 1612 MHz circumstellar OH maser emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in Large Magellanic Cloud. have discovered four new sources LMC, increased number reliable wind speeds IR LMC 5 to 13. Using speeds, as well those Galactic sources, we derived an updated relation for dust driven winds: $v_{exp} \propto Z L^{0.4}$. compare sub-solar metallicity OH/IR with carefully selected samples more metal-rich stars, also at...
Effective temperatures and luminosities are calculated for 1475 921 Tycho-2 107 145 Hipparcos stars, based on distances from Gaia Data Release 1. Parameters derived by comparing multi-wavelength archival photometry to bt-settl model atmospheres. The 1σ uncertainties the stars ±137 ±125 K in temperature ±35 ±19 per cent luminosity. luminosity uncertainty is dominated that of parallax. Evidence infrared excess between 4.6 25 μm found 4256 which 1883 strong candidates. These include asymptotic...
The impact of metallicity on the mass-loss rate from red giant branch (RGB) stars is studied through its effect parameters horizontal (HB) stars. scaling factors Reimers (1975) and Schroder & Cuntz (2005) are determined for 56 well-studied Galactic globular clusters (GCs). median values among are, respectively, {\eta}_R = 0.477 +/- 0.070 (+0.050/-0.062) {\eta}_SC 0.172 0.024 (+0.018/-0.023) (standard deviation systematic uncertainties, respectively). Mass-loss mechanisms RGB have very little...
Complex stellar winds from evolved stars Stars less than eight times the mass of Sun end their lives as planetary nebulae, structures ionized gas thrown off by star and heated exposed core. Planetary nebulae are often bipolar in shape or contain complex morphological features such rings spirals. Decin et al. observed 14 during asymptotic giant branch (AGB) phase evolution, which immediately precedes nebula phase. They found morphologies AGB similar to demonstrated that they produced...
ABSTRACT We present new radio continuum images and a source catalogue from the MeerKAT survey in direction of Small Magellanic Cloud. The observations, at central frequency 1.3 GHz across bandwidth 0.8 GHz, encompass field view ∼7° × 7° result with resolution 8 arcsec. median broad-band Stokes I image Root Mean Squared noise value is ∼11 μJy beam−1. produced these contains 108 330 point sources 517 compact extended sources. also describe UHF (544–1088 MHz) single pointing observation. report...
The characteristics of oxygen-rich and carbon-rich, large amplitude (dK>0.4 mag), asymptotic giant branch variables in the Large Magellanic Clouds are discussed, with an emphasis on those obscured by dust. Near-infrared photometry, obtained over about 8 years, is combined published mid-infrared observations from IRAS ISO to determine bolometric magnitudes for 42 stars. Pulsation periods O-rich stars range 116 0.6 mag, secular or very long period variations which may be associated changes...
We present the results of a survey for OH maser emission at 1612 MHz from dust-enshrouded asymptotic giant branch (AGB) stars and supergiants in Large Magellanic Cloud (LMC) Small (SMC), with Parkes radio telescope, aimed deriving speed superwind double-peaked profiles. Out eight targets LMC we detected five, which three are new detections – no was two SMC targets. first time redshifted components profile extreme red supergiant IRAS 04553−6825, confirming suspicion that its wind had been...
We present a Spitzer Space Telescope spectroscopic survey of mass-losing carbon stars (and one oxygen-rich star) in the Large Magellanic Cloud (LMC). The represent superwind phase on asymptotic giant branch (AGB), which forms major source dust for interstellar medium (ISM) galaxies. Bolometric magnitudes indicate progenitor masses 1.5–2.5 M⊙. spectra cover wavelength range 5–38 μm. They show varying combinations continuum, emission features (SiC, MgS) and molecular absorption bands (C2H2,...
We present the classification of 197 point sources observed with Infrared Spectrograph in SAGE-Spec Legacy program on Spitzer Space Telescope. introduce a decision-tree method object based infrared spectral features, continuum and energy distribution shape, bolometric luminosity, cluster membership, variability information, which is used to classify sample sources. The decision tree has broad application mid-infrared spectroscopic surveys, where supporting photometry information are...
Dust radiative transfer models are presented for 60 carbon stars in the Magellanic Clouds (MCs) which 5‐35 µm Spitzer infrared spectrograph (IRS) spectra and quasi-simultaneous ground-based JHKL photometry available. From modelling, luminosity massloss rate derived (under assumption of a fixed expansion velocity dust-to-gas ratio), ratio silicon carbide (SiC) to amorphous (AMC) dust is also derived. This smaller than observed Galactic stars, as has been noted before. Light curves 36 objects...
Post-AGB stars are key objects for the study of dramatic morphological changes low- to intermediate-mass on their evolution from Asymptotic Giant Branch (AGB) towards Planetary Nebula stage. There is growing evidences that binary interaction processes may very well have a determining role in shaping process many objects, but so far direct evidence still weak. We aim at systematic dust distribution around large sample as probe symmetry breaking nebulae these systems. used imaging mid-infrared...
We observed a sample of evolved stars in the Large and Small Magellanic Clouds (LMC SMC) with Infrared Spectrograph on Spitzer Space Telescope. Comparing samples from SMC, LMC, Galaxy reveals that dust production rate depends metallicity for oxygen-rich stars, but carbon similar pulsation properties produce quantities dust, regardless their initial metallicity. Other also depend As decreases, fraction naked (i.e., dust-free) increases, among strength 8 μm absorption band SiO decreases. Our...
We present an overview of the initial results from Chandra Planetary Nebula Survey (ChanPlaNS), first systematic (volume-limited) X-ray Observatory survey planetary nebulae (PNe) in solar neighborhood. The phase ChanPlaNS targeted 21 mostly high-excitation PNe within ~1.5 kpc Earth, yielding 4 detections diffuse emission and 9 X-ray-luminous point sources at central stars (CSPNe) these objects. Combining with those obtained archival data for all (14) other that have been observed to date, we...
This paper reports variations of polycyclic aromatic hydrocarbons (PAHs) features that were found in Spitzer Space Telescope spectra carbon-rich post-asymptotic giant branch (post-AGB) stars the Large Magellanic Cloud (LMC). The consists two parts. first part describes our spectral observing programme 24 including post-AGB candidates. latter half this presents analysis PAH 20 LMC, assembled from archive as well own programme. We five showed a broad feature with peak at 7.7 micron, had not...