L. J. Smith
A5051840211- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Breastfeeding Practices and Influences
- History and Developments in Astronomy
- Child Nutrition and Feeding Issues
- CCD and CMOS Imaging Sensors
- Solar and Space Plasma Dynamics
- Astrophysics and Cosmic Phenomena
- Calibration and Measurement Techniques
- Spectroscopy and Laser Applications
- Pulsars and Gravitational Waves Research
- Infant Nutrition and Health
- Photocathodes and Microchannel Plates
- Atmospheric Ozone and Climate
- Particle physics theoretical and experimental studies
- Atomic and Molecular Physics
- Satellite Image Processing and Photogrammetry
- Pediatric health and respiratory diseases
Space Telescope Science Institute
2015-2024
United Kingdom Atomic Energy Authority
1975-2024
Culham Science Centre
2024
NHS Lothian
2024
Royal Society for the Protection of Birds
2023
University of Cambridge
2023
APC Microbiome Institute
2023
University College Cork
2023
University College London
2002-2022
Université Laval
2022
We are performing a uniform and unbiased, ~7x7 degrees imaging survey of the Large Magellanic Cloud (LMC), using IRAC MIPS instruments on board Spitzer Space Telescope in order to agents galaxy's evolution (SAGE), interstellar medium (ISM) stars LMC. The detection diffuse ISM with column densities >1.2x10^21 H cm^-2 permits detailed studies dust processes ISM. SAGE's point source sensitivity enables complete census newly formed masses >3 solar that will determine current star formation rate...
This article examines the relative perceived importance of 19 instructor actions in online courses according to both instructors and students. The were culled from guidelines learning literature base then reviewed rated by 14 experts. Thirty‐two 170 students their classes at a large public university private asked review rate these guidelines. Findings show that believe learner performance is more likely tied are focused on course content provide proactive (models, expectations) reactive...
Abstract What are the faintest distant galaxies we can see with Hubble Space Telescope ( HST ) now, before launch of James Webb ? This is challenge taken up by Frontier Fields, a Director’s discretionary time campaign and Spitzer to deeper into universe than ever before. The Fields combines power natural gravitational telescopes massive high-magnification clusters produce deepest observations their lensed obtained. Six clusters—Abell 2744, MACSJ0416.1-2403, MACSJ0717.5+3745,...
The Legacy ExtraGalactic UV Survey (LEGUS) is a Cycle 21 Treasury program on the Hubble Space Telescope aimed at investigation of star formation and its relation with galactic environment in nearby galaxies, from scales individual stars to those ∼kiloparsec-size clustered structures. Five-band imaging near-ultraviolet I band Wide-Field Camera 3 (WFC3), plus parallel optical Advanced for Surveys (ACS), being collected selected pointings 50 galaxies within local 12 Mpc. filters used...
We present a new grid of ionizing fluxes for O and Wolf-Rayet stars use with evolutionary synthesis codes single star H II region analyses. A total 230 expanding, non-LTE, line-blanketed model atmospheres have been calculated five metallicities (0.05, 0.2, 0.4, 1 2 solar) using the WM-basic code Pauldrach et al. (2001) CMFGEN Hillier & Miller (1998). The stellar wind parameters are scaled metallicity both W-R stars. incorporate models into Starburst99 (Leitherer 1999) compare outputs...
view Abstract Citations (388) References (103) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Metal Enrichment, Dust, and Star Formation in Galaxies at High Redshifts. III. Zn CR Abundances for 17 Damped Lyman-Alpha Systems Pettini, Max ; Smith, Linda J. Hunstead, Richard W. King, David L. We present measurements of the abundances zinc chromium a moderately large sample damped Lyman-α systems redshifts between z_abs_ = 1.78 3.03; includes approximately...
We present the results of a detailed UV and optical spectral analysis properties 6 dwarf O-type stars in SMC H II region NGC 346. Stellar parameters, chemical abundances, wind parameters have been determined using NLTE line blanketed models calculated with photospheric code, Tlusty, CMFGEN. The results, particular iron obtained two codes compare very favorably, demonstrating that basic O dwarfs can be reliably static model atmospheres. require microturbulent velocity to match observed...
We report new observations of ZnII and CrII absorption lines in 10 damped \lya systems (DLAs), mostly at redshift $z_{abs} \simgt 2.5$ . By combining these results with those from our earlier survey (Pettini et al. 1994) other recent data, we construct a sample 34 measurements (or upper limits) the Zn abundance relative to hydrogen [Zn/H]; includes more than one third total number DLAs known. The plot as function reinforces two main findings previous study. (1) Damped are metal-poor, all...
SPIRE, the Spectral and Photometric Imaging REceiver, is <i>Herschel<i/> Space Observatory's submillimetre camera spectrometer. It contains a three-band imaging photometer operating at 250, 350 500 <i>μ<i/>m, an Fourier-transform spectrometer (FTS) covering 194–671 <i>μ<i/>m (447-1550 GHz). In this paper we describe initial approach taken to absolute calibration of SPIRE instrument using combination emission from telescope itself modelled continuum solar system objects other astronomical...
We present ∼1000 new candidate Young Stellar Objects (YSOs) in the Large Magellanic Cloud selected from Spitzer Space Telescope data, as part of Surveying Agents a Galaxy's Evolution (SAGE) Legacy program. The YSOs, detected by their excess infrared (IR) emission, represent early stages evolution, still surrounded disks and/or infalling envelopes. Previously, fewer than 20 such YSOs were known. SAGE Point Source Catalog regions color–magnitude space least confused with other IR-bright...
This paper defines the UKIRT Infrared Deep Sky Survey (UKIDSS) Early Data Release (EDR). UKIDSS is a set of five large near-infrared surveys being undertaken with United Kingdom Telescope Wide Field Camera (WFCAM). The programme began in 2005 May and has an expected duration 7 yr. Each survey uses some or all broad-band filter complement ZY JHK. EDR first public release data to European Southern Observatory (ESO) community. All worldwide releases occur after delay 18 months from ESO release....
We present a catalog of 1750 massive stars in the Large Magellanic Cloud (LMC), with accurate spectral types compiled from literature, and photometric for subset 1268 these stars, goal exploring their infrared properties. The consists counterparts Spitzer SAGE survey database, which we uniform photometry 0.3 to 24 μm UBVIJHKs+IRAC+MIPS24 bands. resulting color–magnitude diagrams illustrate that supergiant B[e], red supergiant, luminous blue variable (LBV) are among brightest point sources...
Color-magnitude diagrams (CMDs) are presented for the Spitzer SAGE (Surveying Agents of a Galaxy's Evolution) survey Large Magellanic Cloud (LMC). IRAC and MIPS 24 μm epoch 1 data presented. These represent deepest, widest mid-infrared CMDs their kind ever produced in LMC. Combined with Two Micron All Sky Survey, used to delineate evolved stellar populations LMC, as well Galactic foreground extragalactic background populations. Some 32,000 stars brighter than tip red giant branch identified....
The goal of this paper is to present the results a preliminary analysis extended infrared (IR) emission by dust in interstellar medium (ISM) Large Magellanic Cloud (LMC). We combine Spitzer Surveying Agents Galaxy Evolution (SAGE) and Infrared Astronomical Satellite (IRAS) data correlate with gas tracers H i, CO, Hα. global as well detailed modeling spectral energy distribution (SED) few selected regions. Extended associated neutral, molecular, diffuse ionized phases ISM detected at all IR...
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....
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 study the stellar cluster population in two adjacent fields nearby, face-on spiral galaxy, M83, using WFC3/HST imaging. The clusters are selected through visual inspection to be centrally concentrated, symmetric, and resolved on images, which allows us differentiate between likely unbound associations. compare our sample with previous studies show that differences catalogues largely due inclusion of large numbers diffuse associations within catalogues. luminosity function is well...
We report the large effort which is producing comprehensive high-level young star cluster (YSC) catalogues for a significant fraction of galaxies observed with Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury program. present methodology developed to extract positions, verify their genuine nature, produce multiband photometry (from NUV NIR), and derive physical properties via spectral energy distribution fitting analyses. use nearby spiral galaxy NGC628 as test case demonstrating...
We present and describe the astro-photometric catalog of more than 800,000 sources found in Hubble Tarantula Treasury Project (HTTP). HTTP is a Space Telescope (HST) program designed to image entire 30 Doradus region down sub-solar (~0.5 solar masses) mass regime using Wide Field Camera 3 (WFC3) Advanced for Surveys (ACS). observed near ultraviolet (F275W, F336W), optical (F555W, F658N, F775W), infrared (F110W, F160W) wavelengths. The stellar photometry was measured point-spread function...
We present a detailed study of AV 83, an O7 Iaf+ supergiant, and 69 [OC7.5 III((f))] in the SMC. The stars have similar effective temperatures luminosities but show very different wind signatures. For our we used non-LTE line-blanketed atmosphere code developed by Hillier Miller, which explicitly allows for line blanketing C, N, O, S, Ar, Ne, Fe, other elements. Our finds that 83 has temperature approximately 33,000 K log g ≈ 3.25. It extended photosphere as result "low" surface gravity much...
Measurements of Zn and Cr abundances in 18 damped Lyα systems (DLAs) at absorption redshifts zabs = 0.692-3.390 (but mostly between ≃ 2 3) show that metals dust are much less abundant high-redshift galaxies than the Milky Way today. Typically, [Zn/H] -1.2; as tracks Fe closely Galactic stars all metallicities is only lightly depleted onto interstellar grains, we conclude overall degree metal enrichment ≈ 13.5 Gyr ago (H0 50 km s-1 Mpc-1, q0 0.05) was ~1/15 solar.
We present high dispersion echelle spectroscopy of the very luminous, young super star cluster (SSC) `F' in M82, obtained with 4.2-m William Herschel Telescope (WHT), for purpose deriving its dynamical mass and assessing whether it will survive to become an old globular cluster. measure a stellar velocity 13.4 +/- 0.7 km/s, projected half-light radius 2.8 0.3 pc from archival HST/WFPC2 images, derive 1.2 0.1 x 10^6 solar masses, demonstrating that M82-F is massive, compact determine current...