A5037517484- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Atmospheric Ozone and Climate
- Radio Astronomy Observations and Technology
- Spectroscopy and Laser Applications
- Molecular Spectroscopy and Structure
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Space Exploration and Technology
- Atomic and Molecular Physics
- Calibration and Measurement Techniques
- Tribology and Lubrication Engineering
- Scientific Research and Discoveries
- Atmospheric chemistry and aerosols
- Advanced Chemical Physics Studies
Keele University
2016-2025
Leibniz Institute for Astrophysics Potsdam
2018
University of Manchester
2007-2011
Royal Observatory
2009
National Astronomical Observatory of Japan
2007-2009
Royal Observatory of Belgium
2009
University College London
2007-2009
University of Minnesota
2009
UK Astronomy Technology Centre
2009
Space Telescope Science Institute
2008
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...
The large amount of dust produced by this supernova may help explain the observed in young galaxies.
The VLT-FLAMES Tarantula Survey (VFTS) is an ESO Large Programme that has obtained multi-epoch optical spectroscopy of over 800 massive stars in the 30 Doradus region Magellanic Cloud (LMC). Here we introduce our scientific motivations and give overview survey targets, including near-infrared photometry comprehensive details data reduction. One principal objectives was to detect binary systems via variations their radial velocities, thus shaping observing strategy. Spectral classifications...
Observing more massive stars The number of that form at each mass is known as the initial function (IMF). For most masses, IMF follows a power-law distribution, first determined by Edwin Salpeter in 1955. Schneider et al. used observations nearby star-forming region 30 Doradus (also Tarantula Nebula) and combined these with stellar modeling to determine its IMF. They found above solar masses than predicted distribution. Because also have biggest influence on their surroundings—for instance,...
Abstract The structure and dynamics of the star-forming disk Small Magellanic Cloud (SMC) have long confounded us. SMC is widely used as a prototype for galactic physics at low metallicity, yet we fundamentally lack an understanding its interstellar medium (ISM). In this work, present new model by comparing kinematics young, massive stars with ISM traced high-resolution observations neutral atomic hydrogen (H i ) from Galactic Australian Square Kilometre Array Pathfinder survey....
The new VISual and Infrared Telescope for Astronomy (VISTA) has started operations. Over its first five years it will be collecting data six public surveys, one of these is the near-infrared YJKsVISTA survey Magellanic Clouds system (VMC). This comprises LMC, SMC, Bridge connecting two galaxies fields in Stream. paper provides an overview VMC strategy presents science results. main goals are determination spatially resolved SFH 3D structure system. Therefore, designed to reach stars as faint...
We present the initial results from Spitzer Survey of Small Magellanic Cloud (S3MC), which imaged star-forming body (SMC) in all seven MIPS and IRAC wavebands. find that F_8/F_24 ratio (an estimate PAH abundance) has large spatial variations takes a wide range values are unrelated to metallicity but anticorrelated with 24 um brightness F_24/F_70 ratio. This suggests photodestruction is primarily responsible for low abundance PAHs observed low-metallicity galaxies. use S3MC images compile...
We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated measurements provide 70 micron data improved imaging quality at 100 160 compared to previous 2010. spectra show only weak CO line emission, an upper limit for the 63 [O I] flux, eliminating possibility that contaminations distort previously estimated dust mass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. newly...
We compare atomic gas, molecular and the recent star formation rate (SFR) inferred from H-alpha in Small Magellanic Cloud (SMC). By using infrared dust emission local dust-to-gas ratios, we construct a map of gas that is independent CO emission. This allows us to disentangle conversion factor effects impact metallicity on efficiency gas. On scales 200 pc 1 kpc find characteristic depletion time ~1.6 Gyr, similar observed molecule-rich parts large spiral galaxies spatial scales. shortens much...
We investigate the infrared (IR) properties of cool, evolved stars in Small Magellanic Cloud (SMC), including red giant branch (RGB) and dust-producing supergiant (RSG) asymptotic (AGB) using observations from Spitzer Space Telescope Legacy program entitled: "Surveying Agents Galaxy Evolution Tidally-stripped, Low Metallicity SMC", or SAGE-SMC. The survey includes, for first time, full spatial coverage SMC bar, wing, tail regions at wavelengths (3.6 - 160 microns). identify a combination...
The Small Magellanic Cloud (SMC) provides a unique laboratory for the study of lifecycle dust given its low metallicity (~1/5 solar) and relative proximity (~60 kpc). This motivated SAGE-SMC (Surveying Agents Galaxy Evolution in Tidally-Stripped, Low Metallicity Cloud) Spitzer Legacy program with specific goals studying amount type present interstellar medium, sources winds evolved stars, how much is consumed star formation. mapped full SMC (30 sq. deg.) including Body, Wing, Tail 7 bands...
We present an overview of the HERschel Inventory The Agents Galaxy Evolution (HERITAGE) in Magellanic Clouds project, which is a Herschel Space Observatory open time key program. mapped Large Cloud (LMC) and Small (SMC) at 100, 160, 250, 350, 500 μm with Spectral Photometric Imaging Receiver (SPIRE) Photodetector Array Camera Spectrometer (PACS) instruments on board using SPIRE/PACS parallel mode. overriding science goal HERITAGE to study life cycle matter as traced by dust LMC SMC....
We present comprehensive photometric and spectroscopic observations of the faint transient SN 2008S discovered in NGC 6946. exhibited slow evolution almost no spectral variability during first nine months, implying a high density CS medium. The light curve is similar shape to that 1998S 1979C, although significantly fainter at maximum light. Our quasi-bolometric lightcurve extends 300 days shows tail phase decay rate consistent with ^{56}Co. propose this evidence for an explosion formation...
We estimate the total dust input from cool evolved stars in Small Magellanic Cloud (SMC), using 8 micron excess emission as a proxy for dust-production rate. find that Asymptotic Giant Branch (AGB) and red supergiant (RSG) produce (8.6-9.5) x 10^7 solar masses per year of dust, depending on fraction far-infrared sources belong to star population (with 10%-50% uncertainty individual rates). RSGs contribute least (<4%), while carbon-rich AGB (especially so-called "extreme" stars) account...
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...
Evolutionary models have shown the substantial effect that strong mass-loss rates ($\dot{M}$) can on fate of massive stars. Red supergiant (RSG) is poorly understood theoretically, and so stellar rely purely empirical \mdot-luminosity relations to calculate evolution. Empirical prescriptions usually scale with luminosity effective temperature, but $\dot{M}$ should also depend current mass hence surface gravity star, yielding more than one possible for same position Hertzsprung-Russell...
We compile the first comprehensive census of hot luminous stars in 30 Doradus (30 Dor) star forming region LMC. The extends to a radius 10arcmin (150pc) from central cluster, R136. Stars were selected photometrically and combined with latest spectral types. 1145 candidate identified which >700 considered genuine early type that contribute feedback. assess spectroscopic completeness be 85% outer regions (>5pc) but fall 35% vicinity R136, giving total 500 spectroscopy. Stellar calibrations...
Reliable models of the thermally pulsing asymptotic giant branch (TP-AGB) phase are critical importance across astrophysics, including our interpretation spectral energy distribution galaxies, cosmic dust production, and enrichment interstellar medium. With aim improving sets stellar isochrones that include a detailed description TP-AGB phase, we extend recent calibration AGB population in Small Magellanic Cloud (SMC) to more metal rich Large (LMC). We model LMC populations with TRILEGAL...
We analyse deep images from the VISTA survey of Magellanic Clouds in YJKs filters, covering 14 sqrdeg (10 tiles), split into 120 subregions, and comprising main body Wing Small Cloud (SMC). apply a colour--magnitude diagram reconstruction method that returns their best-fitting star formation rate SFR(t), age-metallicity relation (AMR), distance mean reddening, together with 68% confidence intervals. The data can be approximated by plane tilted East-West direction inclination 39 deg, although...
The VISTA near-infrared YJKs survey of the Magellanic System (VMC) is collecting deep Ks-band time-series photometry pulsating stars hosted by two Clouds and their connecting bridge. Here, we present Y, J, Ks light curves for a sample 717 Small Cloud (SMC) Classical Cepheids (CCs). These data, complemented with our previous results V magnitude from literature, allowed us to construct variety period–luminosity period–Wesenheit relationships, valid Fundamental, First Second Overtone pulsators....
Context: The commonly used extinction laws of Cardelli et al. (1989) have limitations that, among other issues, hamper the determination effective temperatures O and early B stars from optical+NIR photometry. Aims: We aim to develop a new family for 30 Doradus, check their general applicability within that region elsewhere, apply them test feasibility using photometry determine temperature OB stars. Methods: use spectroscopy NIR VLT-FLAMES Tarantula Survey optical HST/WFC3 Doradus we analyze...
We present high angular resolution (~80 mas) ALMA continuum images of the SN 1987A system, together with CO $J$=2 $\!\rightarrow\!$ 1, $J$=6 5, and SiO $J$=5 4 to $J$=7 6 images, which clearly resolve ejecta (dust molecules) ring (synchrotron continuum) components. Dust in is asymmetric clumpy, overall dust fills spatial void seen H$\alpha$ filling that region material from heavier elements. The clumps generally fill space where 5 fainter, tentatively indicating these are locationally...
We recover the spatially resolved star formation history across entire main body and Wing of Small Magellanic Cloud (SMC), using fourteen deep tile images from VISTA survey Clouds (VMC), in YJKs filters. The analysis is performed on 168 subregions size 0.143 deg2, covering a total contiguous area 23.57 deg2. apply colour-magnitude diagram (CMD) reconstruction method that returns best-fitting rate SFR(t), age--metallicity relation, distance mean reddening, together with their confidence...