Search Publications
The PAH emission spectra of Large Magellanic Cloud H II regions
Tielens, A. G. G. M.; Peeters, E.; van der Hulst, J. M. +1 more
A set of ISOPHOT spectra from a sample of H Ii regions in the Large Magellanic Cloud (LMC) is presented. In all the spectra, emission bands arising from Polycyclic Aromatic Hydrocarbons (PAHs) are clearly present. These features are observed to vary considerably in relative strength to each other from source to source and even within 30 Doradus. T…
[CII] at 158 mu m as a star formation tracer in late-type galaxies
Boselli, A.; Gavazzi, G.; Lequeux, J. +1 more
We present a calibration of the massive star formation rate vs. [CII] luminosity relation based on a sample of nearby, late-type galaxies observed with ISO-LWS and imaged in the Hα +[NII] line. The relation holds for far-IR luminosities 108 <= LFIR <=1010.5 Lsun. The derived star formation rates ha…
Spectroscopy of large PAHs. Laboratory studies and comparison to the Diffuse Interstellar Bands
Schmidt, W.; Ehrenfreund, P.; Allamandola, L. J. +4 more
Polycyclic Aromatic Hydrocarbons (PAHs) are thought to be the carriers of the ubiquitous infrared emission bands (UIBs). Data from the Infrared Space Observatory (ISO) have provided new insights into the size distribution and the structure of interstellar PAH molecules pointing to a trend towards larger-size PAHs. The mid-infrared spectra of galac…
Water emission in NGC 1333-IRAS 4. The physical structure of the envelope
Maret, S.; Ceccarelli, C.; Caux, E. +2 more
We report ISO-LWS far infrared observations of CO, water and oxygen lines towards the protobinary system IRAS 4 in the NGC 1333 cloud. We detected several water, OH, CO rotational lines, and two [OI] and [CII] fine structure lines. Given the relatively poor spectral and spatial resolution of these observations, assessing the origin of the observed…
Coronal density diagnostics with Helium-like triplets: CHANDRA-LETGS observations of Algol, Capella, Procyon, epsilon Eri, alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099
Schmitt, J. H. M. M.; Burwitz, V.; Raassen, A. J. J. +5 more
We present an analysis of ten cool stars (Algol, Capella, Procyon, epsilon Eri, alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099) observed with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. This sample contains all cools stars observed with the LETGS presently available to us with integratio…
Asteroids as calibration standards in the thermal infrared for space observatories
Müller, T. G.; Lagerros, J. S. V.
Asteroids have been used extensively as calibration sources for the Infrared Space Observatory (ISO) and are planned to be used by future groundbased, airborne and space-based projects in the thermal infrared (IR) and in the sub-millimetre. We summarize the general IR observational parameters with a focus on space observatories and discuss brightn…
The ages of the globular clusters M 71 and 47 Tuc from Strömgren uvby photometry. Evidence for high ages
Grundahl, F.; Stetson, P. B.; Andersen, M. I.
New uvby CCD photometry for the fairly metal-rich globular clusters M 71 (NGC 6838) and 47 Tuc (NGC 104) is presented. We derive the cluster distances using a sample of field subdwarfs with metallicities determined from uvby photometry and accurate parallaxes from the Hipparcos mission. The biases associated with the main-sequence fitting techniqu…
Fast-rotating nearby solar-type stars, Li abundances and X-ray luminosities. I. Spectral classification, v sin i, Li abundances and X-ray luminosities
Tagliaferri, G.; Pasquini, L.; de Medeiros, J. R. +3 more
We present the results of high-resolution spectroscopic and high-precision photometric observations on a sample of 129 late-F and G-type nearby stars selected on the basis of their large rotational velocity. Using also data from the Hipparcos satellite, CORAVEL and from the ROSAT satellite database, we infer spectral types, compute radial velociti…
Doppler Imaging of stellar magnetic fields. III. Abundance distribution and magnetic field geometry of alpha 2 CVn
Ilyin, I.; Piskunov, N.; Kochukhov, O. +2 more
We used the new magnetic Doppler Imaging code to reconstruct the magnetic field geometry and surface abundance distributions for the classical magnetic CP star alpha 2 CVn. High-resolution spectropolarimetric observations in the Stokes I and V parameters were collected with the SOFIN échelle spectrograph at the Nordic Optical Telescope.…
The relation of PAH strength with cold dust in galaxies
Bianchi, S.; Klaas, U.; Haas, M.
Mid-infrared spectra and submillimetre maps are investigated for five galaxies covering a range of star forming activity. We find a good spatial coincidence between the 850 mu m continuum emission and the strength of the PAH 7.7 mu m line. The PAH 7.7 mu m peak to 850 mu m flux ratio lies in the range around 2 with a moderate dispersion across the…