HST/NICMOS Observations of M82

The irregular galaxy M82 is known as the archetypal starburst galaxy. Its proximity (3.5 Mpc) makes this galaxy an ideal laboratory for studying the properties of its starburst. The detailed morphology of the [FeII] 1.644 μm and emission Pa_α (at 1.87 μm) is revealed by the NICMOS images. The peak of the 2.2 μm continuum brightness(evolved population) lies very close to the dynamical centre. Most of the Pa_α emission (which traces the young population) is distributed in a ring of star formation (with a `hole' lacking line emission at the centre of the galaxy). These observations support the scenario in which the starburst in M82 is propagating outwards. It has long been suggested that the [FeII] emission in starburst galaxies can be used as a measure of supernova (SN) activity. M82 shows a large number of radio supernova remnants (SNRs), approximately 50, lying in the plane of the galaxy. The comparison of the positions of the bright compact [FeII] emitting regions with the location of the radio SNRs shows that there is no one-to-one spatial correspondence between the two emissions, suggesting that the radio and [FeII] emissions trace two populations of SNRs with different ages. Young (a few hundred years) SNRs are best traced by their radio emission, whereas the [FeII] stage lasts for at least a few 10⁴ yr. The compact [FeII] sources contribute only some 20 % of the total [FeII] emission observed in M82. However, much of the remaining unresolved [FeII] emission in the plane of the galaxy may arise from SNRs that expanded and merged into a general interstellar medium within a few 10⁴ yr. Presumably, as much as 70% of the total extinction-corrected [FeII]1.644 μm in M82 is associated with SNRs. The extended and diffuse [FeII] component in M82 seems to be related with the superwind above and below the disc of the galaxy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Usefulness of geological,mineralogical, chemical and chemometric analytical techniques in exploitation and profitability studies of iron mines and their associated elements

Due to the high number of variables involved in mine profitability studies, it is often very difficult to establish connections among them in order to provide a blend of market saleable quality products. In this sense, analytical chemistry together with chemometry are essential and indispensable disciplines to tackle these studies. The aim of this work was to demonstrate the utility of these disciplines to carry out optimization studies of iron mines. For this purpose, one of the most important iron mines of the Iberian Peninsula was chosen, sited in the mountain range of Sierra Menera, near the location of Ojos Negros (Teruel, Spain). Geological, mineralogical and chemical composition of 148 samples was analyzed, corresponding to different depths of three drill holes (named TE1, TE2 and TE3). In particular, aspects concerning to chemical composition are very important, since the mean contents of certain elements, such as phosphorus, sodium and potassium, should be restricted to the established limits to prevent that companies can drive back the raw material if they do not fulfil the necessary requirements. On the other hand, the large number of analysed samples drove us to use a statistical processing of the data. Among other aspects, it provides a way to find possible connections among a high number of variables and classify samples into compositional groups sharing similar composition, in order to limit the mineralised area and to obtain enough information about the amount of those chemical elements associated to iron ores. Data obtained from all these analytical techniques were in good agreement and provide a methodology that can be of wide interest applied to different geological studies.     

Mid-infrared, spatially resolved spectroscopy of the nucleus of the Circinus galaxy

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   A_V ∼ 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..     

The Origin of the Diffuse Hα in Spirals

Using high-quality H_α images of five spiral galaxies, we have studied the luminosity and distribution of the emission from diffuse ionized gas (DIG). The estimated DIG luminosities account for 25–60%of the total H_α emission in each galaxy and analysis of the distribution has shown that the DIG is highly correlated geometrically with the most luminous HII regions of the galaxies. The power required to ionize the DIG is very high. The mean ionization rates per unit surface area of a galaxy disc are of the order of 10⁷ cm^-2 s^-1. Lyman continuum photons (Lyc) from OB asociations are the most probable sources of this ionization. Here we propose a specific model for these sources: we show that the Lyman photon flux that leaks out of the density-bounded HII regions of the galaxies is more than enough to ionize the measured DIG in the five galaxies analysed. This revised version was published online in July 2006 with corrections to the Cover Date.     

LEGRI instrument health. A historical review

LEGRI has been operating successfully on MINISAT-01 since its switch-on the 22nd of May 1997. HouseKeeping (HK) data have been continuously receivedfor nearly two years by LEGRI SOC in Valencia, and subsequently checked on adaily basis and then stored for long term monitoring analysis.LEGRI HouseKeeping data include three critical operating parameters:temperature, power and polarisation voltages. Six temperature sensors arespread over the different LEGRI units: Detector Unit, Data Processing Unit,High Voltage Unit and Star Sensor. Voltages are measured at eight differentpoints. Detector Unit temperature and polarisation voltage are thecritical parameters for LEGRI operation. Solid state detectors aresensitive to changes not only in polarisation but also in temperature.Around one and a half million of measurements for each of the HK fourteen parameters have been recorded and analysed. The data show a very remarkablestability, within the expected margins, and the averages are very close to theoptimal design values. Special attention has been paid to the detectorpolarisation voltages analysis with a mean value of 286 ± 2 V when the detectors are operating. Thermal control over all the LEGRI units shows a remarkable stability in their temperatures.On the detector plane a mean value of T _det = 13 ± 2 ^°C has been found.We can therefore conclude that LEGRI as a system has been operating withinits optimal design conditions. We also want to point out the excellentperformance of the MINISAT-01 thermal control system.     

Adaptive optics near-infrared imaging of NGC 2992 – unveiling core structures related to radio figure-of-8 loops

We present near-infrared adaptive optics, Very Large Array (VLA) radio and Hubble Space Telescope ( HST ) optical imaging of the nearby Seyfert galaxy NGC 2992. Spiral structure and an extension to the west are traced down to the core region at the limiting resolution of our near-infrared images. A faint, diffuse loop of near-infrared and radio emission is also observed to the north, embedded within the prominent 2-arcsec radio loop previously observed to the north-west. Near-infrared colour maps and CO narrow-band imaging are then used to identify which regions may not be purely reddened stellar populations. Our new data provide evidence that the VLA radio-loop morphology in the shape of a figure of 8 represents two components superimposed: (1) outflow bubbles out of the plane of the disc, coincident with the extended emission-line region (EELR); (2) star formation along the spiral arm within the galaxy disc and through the dust lane. The near-infrared continuum emission associated with the outflowing radio bubbles suggests that the radio loops are driven by the active nucleus.     

Extended X-ray emission in the radio-loud galaxy 3C 382

ROSAT /HRI observations of the powerful radio-loud galaxy 3C 382 reveal extended X-ray emission associated with the source. On the basis of this new spatial component, a previous ROSAT /PSPC spectral analysis of the source is revised. Allowing for the presence of an additional thermal component in the PSPC spectrum, the non-thermal component is found to be compatible with the extrapolation of the well-defined 3C 382, 2–10 keV, power-law spectrum into the soft X-ray region. The thermal – extended – component would then account for the soft excess emission previously reported for this source. The origin of this thermal component is not clear. Its luminosity compares with that of rich Abell clusters; yet, the galaxy environment in 3C 382 appears of moderate optical richness. An alternative is that it is the result of a massive extended gaseous atmosphere sustained by the deep gravitational potential well of 3C 382.     

Challenging sub terra nullius: a critical underground urbanism project

ABSTRACT

Underground urban development is rapidly expanding. Like all forms of ‘development’, utilising the underneath of cities can present a range of possibilities and problems. Much underground urban development, however, has been conceptualised through a technical rather than a broader social lens. This is problematic, not least as these developments are usually financed with public money, while their governance is often realised through complicated and opaque public–private partnerships. In this context, the urban underground is often present as sub terra nullius: an epistemologically blank slate waiting to be exploited with the necessary technology and funding. In this paper, the author presents four analytical strata to help us to rethink how urban undergrounds are conceptualised and developed. Drawing on examples from Australia, she presents how we need to appreciate the more-than-human geographies of the underground (stratum 1); critically understand the dynamics of volumetric dispossession (stratum 2); question who owns the underground and how (stratum 3); and rethink how the underground is accessed (stratum 4). By engaging with these themes, we can explore ways to move subterranean urban development away from a technoscientific tunnelling decision-making process to one that engages with the social, political and economic implications of urban infrastructural projects.     

New active galactic nuclei science cases with interferometry

Infrared (IR) interferometry has made widely recognised contributions to the way we look at the dusty environment of supermassive black holes on parsec scales. It finally provided direct evidence for orientation-dependent unification of active galaxies, however it also showed that the classical “torus” picture is oversimplified. New scientific opportunities for AGN have been suggested, and will soon be carried out, focusing on the dynamical aspects of spectrally and spatially resolved interferometry, as well as the potential to employ interferometry for cosmology. This will open interferometry to new scientific communities.