Search Publications
The puzzling theoretical predictions for the luminosity of clumping He burning stars
Weiss, A.; Prada Moroni, P. G.; Degl'Innocenti, S. +3 more
This paper deals with theoretical predictions for He burning models in a range of masses covering the so-called Red Giant Branch phase transition. Taking as a guideline the observational constraints given by Hipparcos parallaxes to the predicted luminosity of models originated from Red Giant progenitors with He core undergoing electron degeneracy,…
X-rays and regions of star formation: a combined ROSAT-HRI/near-to-mid IR study of the rho Oph dark cloud
Grosso, N.; Bontemps, S.; André, P. +2 more
We have obtained two deep exposures of the rho Oph cloud core region with the ROSAT High Resolution Imager. The improved position accuracy (1arcsec -6arcsec ) with respect to previous recent X-ray observations (ROSAT PSPC, and ASCA ) allows us to remove positional ambiguities for the detected sources. We also cross-correlate the X-ray positions wi…
Wind properties of Wolf-Rayet stars at low metallicity: Sk 41 (SMC)
Crowther, P. A.
The stellar properties of Sk 41 (AB4, WN5h), the only known single Wolf-Rayet star in the SMC, are derived from ultraviolet (IUE), optical (AAT) and near-IR (NTT) spectroscopy. Contrary to expectations for low metal environments, the stellar properties of Sk 41 are typical of equivalent WN stars in the Galaxy and LMC, with T* ~ 42kK, lo…
Dwarf spheroidal galaxies in the M81 group imaged with WFPC2
Sarajedini, A.; Dolphin, A. E.; Grebel, E. K. +7 more
We obtained HST/WFPC2 images of the dwarf spheroidal (dSph) galaxies K61, K63, K64, DDO78, BK6N, and kk77 in the M81 group. Our color-magnitude diagrams show red giant branches with tips (TRGB) falling within the range of I = [23.8 -24.0] mag. The derived true distance moduli (DM) of the 6 dSphs ranging from 27.71 to 27.93 mag are consistent with …
ISO observations of a sample of Compact Steep Spectrum and GHz Peaked Spectrum radio galaxies
Pozzi, F.; Bremer, M.; Dallacasa, D. +13 more
We present results from observations obtained with ISOPHOT, on board the ISO satellite, of a representative sample of seventeen CSS/GPS radio galaxies and of a control sample of sixteen extended radio galaxies spanning similar ranges in redshift (0.2 <= z <= 0.8) and radio luminosity (P_{2.7 GHz} >= 1026 W/Hz). The observations…
ISO observations of the reflection nebula Ced 201: evolution of carbonaceous dust
Lequeux, J.; Cesarsky, D.; Gérin, M. +1 more
We present spectrophotometric imaging mid-IR observations of the reflection nebula Ced 201. Ced 201 is a part of a molecular cloud illuminated by a B9.5V star moving through it at more than 12 km s-1. The spectra of Ced 201 give evidence for transformation of very small carbonaceous grains into the carriers of the Aromatic Infrared Band…
Analysis of asymmetric p-mode profiles in GOLF data
García, R. A.; Turck-Chièze, S.; Ulrich, R. K. +8 more
We show here evidence for the necessity of an asymmetric form in modelling the profile of an acoustic mode in the power spectral density. The analysis was performed on a 805-day series of GOLF data (l=0 to 3). The assumptions used for the fits are discussed and their consequences quantified, in particular for the optimum choice of the fitting spec…
Theoretical models for classical Cepheids. VII. Metallicity effects on the Cepheid distance scale
Marconi, M.; Musella, I.; Caputo, F. +1 more
We use theoretical Period-Luminosity and Period-Luminosity-Color relations in the VI passbands, as based on nonlinear, nonlocal and time-dependent convective pulsating models, to predict the reddening and true distance modulus of distant Cepheids observed with the Hubble Space Telescope. By relying on the pulsating models with metal content Z=0.00…
Elementary heating events - Magnetic interactions between two flux sources
Parnell, C. E.; Galsgaard, K.; Blaizot, J.
Observations taken by the SoHO MDI instrument have revealed that the quiet photospheric magnetic flux is, on average, recycled within a few days. As new flux emerges from the convection zone into the photosphere it is moved around by horizontal motions resulting from overshoots of convection cells. These motions cause the magnetic fields extending…
Detection of mid-infrared aromatic hydrocarbon emission features from the Small Magellanic Cloud
Boulanger, F.; Reach, W. T.; Contursi, A. +1 more
The mid-infrared (5-16 mu m) spectral energy distribution for an individual quiescent molecular cloud in the Small Magellanic Cloud (SMC) was observed using ISOCAM. The spectrum is dominated by broad emission bands at 6.2, 7.7, and 11.3 mu m, with weaker bands at 8.6 and 12.7 mu m. As these are the same bands, with similar shape and relative stren…