High spatial resolution spectroscopy at 8–13 μm with T-ReCS on Gemini-S has revealed striking variations in the mid-infrared emission and absorption in the nucleus of the Circinus galaxy (hereafter ...Circinus) on subarcsecond scales. The core of Circinus is compact and obscured by a substantial column of cool silicate dust. Weak extended emission to the east and west coincides with the coronal line region and arises from featureless dust grains which are probably heated by line emission in the coronal emission zone. The extended emission on the east side of the nucleus displays a much deeper silicate absorption than that on the west, indicating significant columns of cool material along the line of sight and corresponding to an additional extinction of AV∼ 25 mag. Emission bands from aromatic hydrocarbons are not subject to this additional extinction, are relatively weak in the core and in the coronal line region, and are much more spatially extended than the continuum dust emission; they presumably arise in the circumnuclear star-forming regions. These data are interpreted in terms of an inclined disc-like structure around the nucleus extending over tens of parsecs and possibly related to the inner disc found from observations of water masers by Greenhill et al..
We present diffraction-limited (FWHM 6 0."3) Gemini/T-ReCS mid-infrared (MIR; N-band or narrowband at 8.7 km) imaging of four luminous infrared galaxies (LIRGs) drawn from a representative local ...sample. The MIR emission in the central few kiloparsecs is strikingly similar to that traced by Paa and generally consists of bright nuclear emission and several compact circumnuclear and/or extranuclear H II regions. The central MIR emission is dominated by these powerful H II regions, consistent with the majority of active galactic nuclei in this local sample of LIRGs contributing a minor part of the MIR emission. The luminous circumnuclear H II regions detected in LIRGs follow the extrapolation of the 8 km versus Paa relation found for M51 H II knots. The integrated central 3-7 kpc of galaxies, however, present elevated 8 km/Paa ratios with respect to individual H II regions, similar to the integrated values for star-forming galaxies. Our results show that the diffuse 8 km emission, not directly related to the ionizing stellar population, can be as luminous as that from the resolved H II regions. Therefore, calibrations of the star formation rate for distant galaxies should be based on the integrated 8 km emission of nearby galaxies, not that of the H II regions alone.
Using the Thermal Region Camera and Spectrograph (T-ReCS) attached to the Gemini South 8 m telescope, we have detected and resolved 10 mu m emission at the position of the inner equatorial ring (ER) ...of supernova SN 1987A at day 6067. "Hot spots" similar to those found in the optical and near-IR are clearly present. The morphology of the 10 mu m emission is globally similar to the morphology at other wavelengths from X-rays to radio. The observed mid-IR flux in the region of SN 1987A is probably dominated by emission from dust in the ER. We have also detected the ER at 20 mu m at a 4 capital sigma level. Assuming that thermal dust radiation is the origin of the mid-IR emission, we derive a dust temperature of 180image K and a dust mass of image x 10 super(-5) M sub(o) for the ER. Our observations also show a weak detection of the central ejecta at 10 mu m. We show that previous bolometric flux estimates (through day 2100) were not significantly contaminated by this newly discovered emission from the ER. If we assume that the energy input comes from radioactive decays only, our measurements, together with the current theoretical models, set a temperature of 90 K < T < 100 K and a mass range of 10 super(-4) to 2 x 10 super(-3) M sub(o) for the dust in the ejecta. With such dust temperatures the estimated thermal emission is image x 10 super(35) ergs s super(-1) from the inner ring and image x 10 super(36) ergs s super(-1) from the ejecta. Finally, using SN 1987A as a template, we discuss the possible role of supernovae as major sources of dust in the universe.
Millions of chemical protective gloves are used every day in Europe. Unfortunately, many are not achieving the level of performance needed to protect the health of the worker, although neither ...employer nor user are aware of this. The way in which such gloves perform is complex and affected by a whole range of factors. A method of integrating these into a simple method for selection and use has proved to be extremely difficult. This presentation will review the many factors that affect glove performance under actual working conditions and show how a system for the selection and use of gloves for chemical protection might be developed. A novel method for testing gloves under actual working conditions so as to correctly identify performance will be proposed.
This work explores in detail the relation between the 8 mum and the Paa emissions for 122 H ii regions identified in a sample of 10 low-z LIRGs with nearly constant metallicity image . We use Gemini ...T-ReCS high spatial resolution (image0.4(image )image120 pc for the average distance of 60 Mpc of our sample) mid-infrared imaging (at 8.7 or 10.3 mum), together with HST NICMOS continuum and Paa images. The LIRG H ii regions extend the image vs. image relation found for H ii knots in the high-metallicity SINGS galaxies by about 2 orders of magnitude to higher luminosities. Since the metallicity of the LIRG sample is nearly constant, we can rule out this effect as a cause for the scatter seen in the relationship. In turn, it is attributed to two effects: age and PAH features. The image ratio, which varies by a factor of 10 for the LIRG H ii regions, is reproduced by a model with instantaneous star formation and ages ranging from image4 to 7.5 Myr. The remaining dispersion around the model predictions for a given age is probably due to differential contributions of the PAH features (the 8.6 mum, in our case) to the 8 mum emission from galaxy to galaxy.
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![Understanding the 8 [mu]m v...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X/small "Understanding the 8 [mu]m versus Paa Relationship on Subarcsecond Scales in Luminous Infrared Galaxies")