ISO-LWS study of pre-main sequence sources

We present the results obtained with the ISO Long Wavelength Spectrometer on a sample of Pre-MS sources, where several molecular lines of CO, H2O and OH have been detected. The analysis of the CO lines indicates that gas temperatures as low as 200 K are consistent with the data. This would be in agreement with the relatively low abundance of water in the gas phase measured in most of the objects

Molecular line emissions from pre main sequence objects

We present some preliminary results obtained with the LWS G.T. programme on the study of young objects driving molecular outflows. In particular, we discuss the importance of molecular emission in these sources and address the role of the H20 cooling

Far infrared spectroscopy of the B335 region

We present far infrared spectra, obtained with the Long Wavelength Spectrometer (LWS) onboard the ISO satellite, on the B335 dark cloud region. In particular, deep integration spectra were acquired on the far infrared outflow exciting source, located in the B335 core, and on the three associated Herbig Haro (HH) objects HH119 A, B and C. In addition, we mapped a region of about 12' in RA and 5' in DEC covering the whole molecular outflow. A [CII] 157μm emission uniformely distributed in all the region is observed, with the intensity expected for a photodissociation region excited by the average interstellar field. The [OI]63μm emission is detected only from the HH objects and from the B335 FIR source; the observed line intensity is in agreement with the existing shock models. CO line emission from the rotation level J=15 to J=18 are detected in B335 FIR only: we model this emission as due to a compact (7x10-3 pc), warm (T=150 K) and dense (nH2 = 4x106 cm-3) region. We think that such a warm gas connot be excited in the collapsing envelope as modelled for this source. Finally, we find that the thermal emission of the FIR source could be fitted by a model assuming a free-fall density distribution law ρ α r-1.5, although a flatter density profile (r-0.5 produces a much better fit with the LWS spectrum shortward of 60μm

Herschel imaging of the dust in the Helix Nebula (NGC 7293)

In our series of papers presenting the Herschel imaging of evolved planetary nebulae, we present images of the dust distribution in the Helix nebula (NGC 7293). Images at 70, 160, 250, 350, and 500 micron were obtained with the PACS and SPIRE instruments on board the Herschel satellite. The broadband maps show the dust distribution over the main Helix nebula to be clumpy and predominantly present in the barrel wall. We determined the spectral energy distribution of the main nebula in a consistent way using Herschel, IRAS, and Planck flux values. The emissivity index of 0.99 +/- 0.09, in combination with the carbon rich molecular chemistry of the nebula, indicates that the dust consists mainly of amorphous carbon. The dust excess emission from the central star disk is detected at 70 micron and the flux measurement agree with previous measurement. We present the temperature and dust column density maps. The total dust mass across the Helix nebula (without its halo) is determined to be 0.0035 solar mass at a distance of 216 pc. The temperature map shows dust temperatures between 22 and 42 K, which is similar to the kinetic temperature of the molecular gas, strengthening the fact that the dust and gas co-exist in high density clumps. Archived images are used to compare the location of the dust emission in the far infrared (Herschel) with the ionized (GALEX, Hbeta) and molecular hydrogen component. The different emission components are consistent with the Helix consisting of a thick walled barrel-like structure inclined to the line of sight. The radiation field decreases rapidly through the barrel wall.Comment: 8 pages, 9 figures, revised version A&A in pres

An investigation of the B335 region through far infrared spectroscopy with ISO

We present far infrared spectra of the B335 dark cloud region, obtained with the Long Wavelength Spectrometer (LWS) on-board the ISO satellite. Deep spectra were obtained towards the far infrared outflow exciting source, located in the B335 core, and on the three associated Herbig Haro (HH) objects HH119 A, B and C. In addition, a region of about 9' in RA and 4' in Dec. was mapped which covers the whole molecular outflow. [CII]158 μm emission was found to be uniformly distributed across the observed region, with the intensity expected for a photodissociation region excited by the average interstellar field. The [OI]63 μm emission was detected only towards two out of the three HH objects and from the B335 FIR source; excitation from the high-velocity shocks responsible for the HH119 knots can account for the observed line intensity. CO line emission from the rotational levels J=15 to J=18 was detected only towards B335 FIR and can be modelled as arising in warm gas whose excitation temperature is in the range 150-800 K, located in a compact ( ~ 10-3 pc) and dense (nH2 ~ 106 cm-3 ) region. If we assume that the CO J = 6→5 line observed from the ground is also emitted from the same gas component, we derive for this component a temperature of 350 K and a density of 5•105 cm-3. Current collapse models for the B335 core fail to predict the presence of such warm gas in the infalling source envelope, at the spatial scales implied by our model fit. It is likely that the molecular emission is excited in a low-velocity (v ~ 10 km s-1 ) non-dissociative shock, originating at the base of the flow

ISO-LWS two colour diagram of young stellar objects

We present a [60--100] vs. [100--170] $\mu$m two colour diagram for a sample of 61 young stellar objects (YSOs) observed with the Long Wavelength Spectrometer (LWS) on-board the Infrared Space Observatory (ISO). The sample consists of 17 Class 0 sources, 15 Class I, 9 Bright Class I ($L_{\rm bol}>10^4 L_\odot$), 20 Class II (14 Herbig Ae/Be stars and 6 T Tauri stars). We find that each class occupies a well defined region in our diagram with colour temperatures increasing from Class 0 to Class II. Therefore the [60--100] vs. [100--170] two colours diagram is a powerful and simple tool to derive from future (e.g. with the Herschel Space Observatory) photometric surveys the evolutionary status of YSOs. The advantage over other tools already developed is that photometry at other wavelengths is not required: three flux measurements are enough to derive the evolutionary status of a source. As an example we use the colours of the YSO IRAS 18148$-$0440 to classify it as Class I. The main limitation of this work is the low spatial resolution of the LWS which, for some objects, causes a high uncertainty in the measured fluxes due to the background emission or to the source confusion inside the LWS beam.Comment: 7 pages, 2 figures, requires mn2e document class. Accepted by MNRA

IRIS Guidelines: Early Intervention in Psychosis IRIS Guidelines Update September 2012

Revision of the original 1998 IRIS Guidelines

Far-infrared cooling lines in pre-MS sources

We review the results of the observations in the 45-190 μm wavelength range with the ISO Long Wavelength Spectrometer of a sample of Class 0, Class I, Class II pre-Main Sequence objects. We briefly discuss the role of [OI] and of molecular lines in the cooling of these sources