A5075282379- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- High-pressure geophysics and materials
- Planetary Science and Exploration
- Astronomy and Astrophysical Research
- Atmospheric Ozone and Climate
- Geochemistry and Geologic Mapping
- Gamma-ray bursts and supernovae
- Geological and Geochemical Analysis
- Glass properties and applications
- Molecular Spectroscopy and Structure
- Geology and Paleoclimatology Research
- SAS software applications and methods
- Spectroscopy and Laser Applications
- Astrophysics and Cosmic Phenomena
- Optical and Acousto-Optic Technologies
- Distributed and Parallel Computing Systems
- Gas Dynamics and Kinetic Theory
- Chemical Thermodynamics and Molecular Structure
- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Geotechnical and Geomechanical Engineering
- Aerodynamics and Fluid Dynamics Research
- Astronomical Observations and Instrumentation
Cardiff University
2004-2023
University College London
2001-2011
Space Telescope Science Institute
2006
Louisiana State University
2006
University of Manchester
2006
Geological Society of London
2004
Linnean Society of London
2004
American Astronomical Society
2004
English Heritage
2004
Queen Mary University of London
1999-2003
Infrared spectral properties of silicate grains in interplanetary dust particles (IDPs) were compared with those astronomical silicates. The ∼10-micrometer silicon-oxygen stretch bands IDPs containing enstatite (MgSiO 3 ), forsterite (Mg 2 SiO 4 and glass embedded metal sulfides (GEMS) exhibit fine structure bandwidths similar to solar system comets some pre–main sequence Herbig Ae/Be stars. Some GEMS a broad, featureless band observed interstellar molecular clouds young stellar objects....
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...
This paper describes a James Clerk Maxwell Telescope (JCMT) legacy survey that has been awarded roughly 500 hr of observing time to be carried out from 2007 2009. In this survey, we will map with SCUBA‐2 (Submillimetre Common‐User Bolometer Array 2) almost all the well‐known low‐mass and intermediate‐mass star‐forming regions within 0.5 kpc are accessible JCMT. Most these locations associated Gould Belt. From observations, produce flux‐limited snapshot star formation near Sun, providing...
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...
Absorption coefficients associated with atomic motions of species expected in astronomical environments are determined from infrared measurements various hydrosilicates, hydrated magnesium oxide, and the Al-bearing chain silicate, sapphirine. Band types measured include O—H stretching modes near 3 μm, Si—O 10 Si—O—Si bends 14 O—Si—O 20 translations cations such as Mg Ca 50-200 μm. We obtain data films varying thickness use a ratioing method. First, bandstrengths fundamentals were spectra...
High signal-to-noise ratio spectra are presented of the 10-μm silicate absorption feature in lines sight towards Elias 16 and 18 Taurus dark cloud, heavily reddened supergiant Cyg OB2 no. 12. The observations fitted with laboratory astronomical to produce intrinsic profiles. These features, which represent molecular-cloud diffuse ISM dust respectively, better emissivity Trapezium μ Cephei than they those laboratory, terrestrial, or other circumstellar silicates. difference width between band...
Far-infrared spectra of laboratory silicates are normally obtained at room temperature even though the grains responsible for astronomical silicate emission bands seen wavelengths >20 μm likely to be temperatures below ∼150 K. In order investigate effect on spectra, we have absorption powdered forsterite and olivine, along with two orthoenstatites diopside clinopyroxene, 3.5±0.5 K (295±2 K). To determine changes in resolution must increased from ∼1 0.25 cm−1 both temperatures, because a...
The 10- and 18-µm spectroscopy of a variety galactic environments reveals smooth bands which have been associated with (respectively) Si–O stretching bending modes in amorphous silicates, since the spectra crystalline silicates are narrow highly structured. standard approach to interpretation astronomical is assume that then add components (usually single olivine followed by pyroxene) match fine structures data. Conversely, this analysis we gross properties profiles – full width at...
A band of pure crystalline forsterite (100 per cent Mg2SiO4) occurs at 69.67 μm room temperature (295 K); for olivines with ≳10 Fe the corresponding feature is ≳73 μm. The Mg-rich observed in a variety ISO LWS spectra, but Fe-rich olivine not. For 10 astronomical sources our sample, peaks 68.9–69.3 range and narrows decreasing peak wavelength. This consistent shortwards shifting when laboratory samples are cooled to 77 K (69.07 μm) 3.5 (68.84 μm). shifted produced by lattice contraction...
Dust emission from the Type II supernova SN 2002hh in NGC 6946 has been detected at mid-infrared wavelengths by Spitzer Space Telescope 590 to 758 days after outburst and confirmed higher angular resolution Gemini North mid-IR observations. The day 600 5.8-24 μm can be fit a 290 K blackbody having luminosity of 1.6 × 107 L☉. minimum emitting radius 1.1 1017 cm is too large for dust have formed ejecta. Using radiative transfer models realistic grain parameters, fits observed flux distribution...
IRAS 16279-4757 belongs to a group of post-AGB stars showing both PAH bands and crystalline silicates. We present mid-infrared images, that resolve the object for first time. The morphology is similar `Red Rectangle' (HD 44179), prototype with PAHs A two-component model images suggest dense oxygen-rich torus, an inner, low-density carbon-rich region bipolar outflow. are enhanced at outflow, while continuum emission concentrated towards center. Our findings support suggestion mixed chemistry...
Stars form in the densest, coldest, most quiescent regions of molecular clouds. Molecules provide only probes that can reveal dynamics, physics, chemistry, and evolution these regions, but our understanding inventory sources how this is related to their physical state rudimentary incomplete. The Spectral Legacy Survey (SLS) one seven surveys recently approved by James Clerk Maxwell Telescope (JCMT) Board Directors. Beginning 2007, SLS will produce a spectral imaging survey content...
The distinct patterns, relatively low intensities and peak positions of overtone-combination bands silicates oxides suggest that the 5–8 μm spectral region can provide clues for dust composition when near optically thick conditions exist 10-μm silicate feature. We present 1000–2500 cm−1 room-temperature laboratory spectra obtained from powders silicate, aluminate nitride minerals glasses. exhibit overtone absorption with mass coefficients ∼100 times weaker than fundamentals. These data are...
Pyroxene crystals are common in meteorites but few compositions have been recognized astronomical environments. We present quantitative room-temperature spectra of 17 Mg-- Fe-- and Ca--bearing ortho- clinopyroxenes, a Ca-pyroxenoid order to discern trends indicative crystal structure wide range composition. Data produced using Diamond Anvil Cell: our band strengths up 6 times higher than those measured KBr or polyethylene dispersions, which include variations path length (from grain size)...
Abstract— Infrared spectra of mineral grains from primitive meteorites could be useful for comparison with astronomical infrared since some their might similar to those formed in the planet-forming disks around young stars or envelopes surrounding late-type stars. To assess usefulness meteorite spectra, olivine separated have been analyzed using FTIR microscope techniques 2–16 μm wavelength range. The sub-micron sizes made a complex preparation process necessary. Five characteristic bands...
We present mid-infrared spectra from individual enstatite silicate grains separated primitive type 3 chondritic meteorites. The 2–16 μm transmission were taken with microspectroscopic Fourier-transform infrared (FT-IR) techniques as part of a project to produce data base minerals meteorites for comparison astronomical spectra. In general, the wavelength bands increases proportion Fe. However, wavelengths strong En100 at 10.67 and 11.67 decrease increasing Fe content. 11.67-μm band exhibits...
We present low resolution 10-μm spectra of the newly identified diffuse interstellar medium (ISM) sightlines towards StRS 217 and 371 a new spectrum Cyg OB2 no. 12 obtained at UK Infrared Telescope (UKIRT) with Michelle imager/spectrometer. As previously, μ Cephei emissivity better represents profile silicates than does broader Trapezium which is characteristic dust in molecular clouds. These together seven published by Roche & Aitken comprise majority data set for ISM. The observed sample...
Disc and sphere dust models are used to fit 8–13 μm flux spectra of 19 low-mass young stellar objects (YSOs) five Herbig AeBe stars. The 13 non-photospheric YSOs in quiescent environments the stars have mean disc temperature indices 0.4, indicating that emission arises from optically thin layers above a flared thick disc; 10 out 14 YSO four features contain an silicate component. radius peak 10-μm for nine is 10–130 au, three 10–30 au size. In contrast, disrupted molecular clouds been shaped...
In this era of spatially resolved observations planet forming disks with ALMA and large ground-based telescopes such as the VLT, Keck Subaru, we still lack statistically relevant information on quantity composition material that is building planets, total disk gas mass, ice content dust, state water in planetesimals. SPICA an infrared space mission concept developed jointly by JAXA ESA to address these questions. The key unique capabilities enable research are (1) wide spectral coverage...
We present new room-temperature 1100 - 1800 cm^{-1} spectra of melilite silicates and 600 2000 three randomly orientated fine-grained carbonates to determine the possible carrier(s) a 6.9~micron absorption feature observed in variety dense astronomical environments including young stellar objects molecular clouds. focus on low-mass post-AGB star Sakurai's Object which has been forming substantial quantities carbonaceous dust since an eruptive event 1990s. Large grains cannot be responsible...
ABSTRACT A pair of 6.0 and 6.9 μm absorption features are frequently observed in Milky Way (MW) molecular-clouds YSOs; they also occur the z = 0.886 rest-frame a molecule-rich spiral galaxy obscuring blazar PKS 1830–211. I calibrate χ2-fitting methods, which match observations with two or three laboratory spectra. The 6.0-μm component is dominated by H2O ice, as expected. Included MW sources were selected using opacity criteria limit range explored H2O-ice column densities to 1.6–2.4 × 1018...
Dust emission in the non-photospheric 10-μm continua of HL Tau and Taurus-Elias 7 (Haro6-10, GV Tau) is distinguished from foreground silicate absorption using a simple disc model with radial power-law temperature mass–density distributions based on IR–submm T Tauri stars by Adams, Lada & Shu extinction. The resulting profiles are remarkably similar to those field star 16 obtained Bowey, Adamson Whittet. fitted indices 0.44 (HL 0.33 (Elias 7) agreement Boss's theoretical models 200–300 K...
ABSTRACT 6–14 μm Spitzer spectra obtained at 6 epochs between 2005 April and 2008 October are used to determine temporal changes in dust features associated with Sakurai’s Object (V4334 Sgr), a low mass post-AGB star that has been forming an eruptive event since 1996. The obscured carbon-rich photosphere is surrounded by 40-milliarcsec torus 32 arcsec PN. An initially rapid mid-infrared flux decrease stalled after 21. Optically thin emission due nanometre-sized SiC grains reached minimum...