The results of FIR spectroscopic mapping observations of the Carina and Sharpless 171 regions with ISO/LWS and SWS are presented. Quite strong [SiII]35 μm emission has been detected in both regions. It is well correlated with [NII]122 μm emission, indicating that it originates mostly from low-density ionized gas. The ratio of the lines shows that S+ gas must be more than 35% of the solar abundance in the ionized medium, suggesting clear observational evidence for the dust destruction in the interstellar medium. We have also found a small line ratio of [OI]63 μm to 145 μm lines (<10) in both regions. The observed large ratio as well as their spatial distribution cannot be accounted for by standard PDR models, even if taking account of the pumping by ultraviolet radiation. We propose that [OI]63 μm line is absorbed in the cold gas between the line emitting region and us.

The balloon borne experiment PRONAOS has measured the sub-millimetre emission from the diffuse interstellar medium to a quiescent filament in the Taurus molecular cloud. We model the output emission of this filament using a radiative transfer code and an independent tracer of the total column density (near infrared extinction). We show that inside the filament the transiently heated particles responsible of the 60 μm emission are removed and the dust sub-millimetre emissivity is increased by a significant factor, 3.4+0.3-0.7 (for typically nH > 3 ± 1 × 103 cm-3, AV > 2.1 ± 0.5). This induces a deficit in the IRAS I60 μm/I100 μm flux ratio in comparison with the diffuse interstellar medium and a decrease of the grain equilibrium temperature in excess to that predicted by extinction.

We have begun a survey of lesser-known star formation regions using the Kitt Peak 12-meter telescope, currently operated by Steward Observatory. Our goal is to compile a database of molecular outflows in these under-studied regions, many of which lie at distances greater than 500 pc. We present our 12CO (J = 1 → 0) On-the-Fly maps, along with HIRES-processed IRAS data, of selected molecular clouds. Our IRAS HIRES maps reveal the more luminous members of the embedded young stellar population, while the CO observations (55" beam, 0.26 km s-1 velocity resolution) allow us to identify a number of previously unknown molecular outflows.

Pre-stellar cores are defined to be the stage of star formation that preceeds the formation of a hydro-static protostar. We have observed a number of cores believed to be pre-stellar in nature in the submillimetre continuum with SCUBA on the JCMT. 37 cores were detected at 850 μm - 13 of them with high signal-to-noise. Radial density profiles of these 13 show flattened inner regions and sharp boundaries consistent with some models of the pre-collapse phase of protostar formation. Simple models are fitted to the core radial density profiles to assess their stability against collapse.

The ISO galactic survey provides images of the inner disk of the Galaxy in two broad filters (around 7 and 15 μm) over some 15 square degrees, away from the brightest star forming regions. A catalogue of infrared dark clouds has been derived through a multiresolution analysis of these images. Most of them are condensed cores of large molecular clouds, several kpc away from the Sun, seen in absorption in front of the diffuse galactic emission. These cores are internally structured. The 7 to 15 μm contrast ratio is 0.75 ± 0.15 for the clouds located away from the Galactic Centre (|l| > 1°) and 1.05 ± 0.15 for the clouds closest to the Galactic Centre (|l| < 1°, |b| < 0.2°). Using a simple absorption model, we derive a 7 to 15 μm opacity ratio equal to 0.7 ± 0.1 and estimate the opacity of a few objects at 15 μm in the range 1 to 4.

Large scale (~0.6 sq deg) mapping of the giant Galactic star forming complex W 51 has been carried out simultaneously in two trans-IRAS far infrared (FIR) bands centered at ~200 and 130 μm using the TIFR 100 cm balloon borne FIR telescope. The choice of the bands is motivated by the aim of studying the emission from the cold dust (T< 30 K) component. These maps with ~1' spatial resolution, show extended emission with structures. Nearly identical beams in the two bands have enabled us to reliably determine the distribution of dust temperature T(130/200), and optical depth τ200, in the central region of the W 51 complex. A total of 25 discrete sources have been extracted from the 200 μm map, of which 8 have been associated with IRAS PSC sources and 16 with sources in HIRES processed IRAS maps at 100, 60, 25 & 12 μm bands. The values of the emissivity power law index β in FIR, show wide variation among these sources.

We have studied variations of physical parameters in the circumstellar envelope of carbon-rich Mira variable, T Dra, at different pulsation phases. After comparing the ISO/SWS spectra of T Dra with spectral energy distributions (SEDs) calculated in models, we could find the best fitted parameters for the physical state of the dust envelope at each phase. The variations of parameters, effective temperature, fraction of SiC grains, mass loss rates and inner radius of shell are found to have nearly the same trend as that of light curve. The other parameters, grain size, optical depth, radius of central star and dust temperature at the inner boundary of envelope, are inversely varing to the light curve. We have found that most physical parameters vary within factor 2, while mass loss rate varies more than factor 3 during pulsation period.

ISOGAL, one of the most important programs observed by ISO, is a 7-15 μm ISOCAM survey, with 6" pixels and sensitivity around 15 mJy, of ≈18 deg2 in the Galactic Plane mostly interior to |l| = 30°. In combination with near-infrared DENIS data, ISOGAL data allow detailed studies of cold stellar populations and Galactic structure in regions highly obscured throughout the inner Galaxy. Version 1 of the ISOGAL Point Source Catalogue is submitted for publication and will be available through CDS. It contains about 105 stars, with associated KJI DENIS data for most of them. Most of these sources are AGB stars and red giants, with a number of dusty young stars.

The Inner Region of the Galaxy has been enigmatic. Some interesting results are becoming available now from the highly promising near and mid infrared surveys such as DENIS, 2MASS, ISOGAL, of this region. The DENIS and ISOGAL surveys have already produced several interesting results over the past couple of years. We have made complementary observations towards the M 16 starforming region to provide additional data at an intermediate wavelength (H band) compared to the DENIS survey. The data will be used in combination with the other 5 bands from the ISOGAL/DENIS survey to characterise the stellar populations in this region.

The FIRBACK survey is a deep imaging survey carried out with ISOPHOT on board ISO, at 170 μm. The survey covers ≈4 sq deg in three high galactic latitude fields (FIRBACK South Marano, FIRBACK North 1 and FIRBACK/ELAIS North 2). In these fields, fluctuations due to unresolved extra-galactic sources were isolated for the first time [1]. We are using a P(D) (probability distribution of fluctuations) analysis to gain information about the N(≥S) curve of the unresolved sources which make up the background. Many planned surveys (e.g. SIRTF, FIRST, PLANCK...) will pose the same analysis challenges and we hope that the outcome of this study will be useful in that context. As a preparation to the analysis of the FIRBACK maps we analyze simulated sky maps. We create histograms of number of pixels per flux bin. The histograms are binned such that there are enough pixels per bin to allow us to apply Gaussian estimates for the errors. We then calculate the expected number of pixels within the relevant flux ranges and evaluate the χ2 statistic. We will use a maximum likelihood algorithm to find the parameters of N(≥S).

We investigate the origin of the variance in dust-to-gas ratio, D, among blue compact dwarf galaxies (BCDs), finding that the observed variance can be reproduced by two effects: (i) variation of gas mass contained in star-forming region; (ii) the contribution of type Ia SNe to total SN rate. The two effects are found to affect largely D when the metallicity reaches the typical value for BCDs. The two effects can be caused by intermittent star formation activity in BCDs.

We formulate the relation between the beam pattern and the source confusion limit. In the formula for the general number counts, the upper cutoff of the integration is set to obtain a numerically reasonable result. The upper cutoff corresponds to the beam area, so we input the beam pattern as the two-dimensional array of the Point Spread Function (PSF). Based on the representative number counts, we evaluate the source confusion typical of various infrared spacecrafts (e.g. ASTRO-F[1]).

We show empirical and theoretical models of infrared galaxy evolution to explain observed number counts and cosmic background, and comment on the discrepancy between their interpretations. Then we discuss some serious observational problems caused by confusion. We introduce an analytic formulation for the bias caused by confusion.

We are modeling the spectra of dwarf galaxies from infrared to submillimeter wavelengths to understand the nature of the various dust components in low-metallicity environments, which may be comparable to the ISM of galaxies in their early evolutionary state. The overall nature of the dust in these environments appears to differ from those of higher metallicity starbursting systems. Here, we present a study of one of our sample of dwarf galaxies, NGC 1569, which is a nearby, well-studied starbursting dwarf. Using ISOCAM, IRAS, ISOPHOT and SCUBA data with the Désert et al. (1990) [1] model, we find consistency with little contribution from PAHs and Very Small Grains and a relative abundance of bigger colder grains, which dominate the FIR and submillimeter wavelengths. We are compelled to use 4 dust components, adding a very cold dust component, to reproduce the submillimetre excess of our observations.

The observability of hydrogen molecules in absorption was investigated for infrared lines against bright infrared sources. The absorption efficiency of the hydrogen molecules becomes comparable with or larger than that of the dust grains in the metal-poor condition expected in the early Universe. If we can use bright infrared continuum sources behind the molecular gas clouds, the absorption measurement of the hydrogen molecules will be an important technique to explore the primordial gas clouds that are contracting into first-generation objects.

The molecular gas mass in nearby galaxies is generally estimated using 12CO(1-0) line intensities and assuming the X conversion factor between I(CO) and N(H2) measured in the solar neighborhood. It is however known that this X conversion factor is not universal since it changes with metallicity, cosmic ray density and UV radiation field. Far-IR data in the spectral range 100-1000 μm can be used to estimate the molecular gas content of late-type galaxies in an independent way of CO line measurements once a metallicity-dependent dust to gas ratio is assumed, allowing a direct estimate of X. This exercise is presented here for a large sample of galaxies with available multifrequency data using ISOPHOT and IRAS far-IR data. X spans from ~1020 mol cm-2 (K km s-1)-1 in giant spirals to ~1021 mol cm-2 (K km s-1)-1 in dwarf irregulars. The relationships between X and the UV radiation field (as traced by the Hα[NII]E.W.), the metallicity and the H band luminosity are analysed.

This paper reviews recent continuum surveys done at (sub)millimeter wavelengths towards z>3.7 quasars and observations of the CO line emission in high z sources.

The FIRBE (Far-Infrared Balloon-Borne Experiment) pro ject is focused on mapping of the far-infrared emission from the Galaxy and external galaxies with the same spatial resolution as that of the IRAS. Two dimensional array on a low emissivity telescope is a powerful facility for wide-area survey.

As the datasets and catalogues produced by space missions and surveys grow larger and more complex, the need in innovating solutions for providing a wide and efficient access to the final observational product becomes more obvious. CDS is one of the leading data centers working at devising these solutions, as part of a world-wide network of data and archive centers, data managers, publishers.

We present the results from our first observing runs with the South Pole Imaging Fabry-Perot Inteferometer (SPIFI). SPIFI is a direct detection imaging spectrometer for use in the submillimeter - the first of its kind. SPIFI employs a 5 × 5 element array of bolometers as its focal plane, and uses two Fabry-Perot in series as its resolution achieving devices. To date, SPIFI has had 5 observing runs on the 15 meter James Clerk Maxwell Telescope (JCMT), three of which were entirely weathered out. During the two good runs, we obtained fully sampled maps in the 370 μm [CI] fine structure line and 372 μm CO(7→6) rotational line of the Galactic Center and the nuclei of several infrared bright galaxies. We present the results, and preliminary analysis of the data obtained for several of these sources below. To date, we have only used SPIFI in the 350 μm telluric window, but SPIFI can also access the 450 and 600 μm windows available to the JCMT, and the far-IR 200 μm window available to the NSF's 1.7 m AST/RO telescope at the South Pole. SPIFI is fully described in [1,2,9].