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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…
Jupiter's hydrocarbons observed with ISO-SWS: vertical profiles of C_2H_6 and C_2H_2, detection of CH_3C_2H
Lellouch, E.; Encrenaz, T.; Feuchtgruber, H. +3 more
We have analysed the ISO-SWS spectrum of Jupiter in the 12-16 mum range, where several hydrocarbons exhibit rovibrational bands. Using temperature information from the methane and hydrogen emissions, we derive the mixing ratios (q) of acetylene and ethane at two independent pressure levels. For acetylene, we find q=(8.9+1.1-0.6
Adaptive optics images at 3.5 and 4.8 µ m of the core arcsec of NGC 1068: more evidence for a dusty/molecular torus
Alloin, D.; Marco, O.
Adaptive optics observations of NGC 1068 have allowed us to reach with a 4 m class telescope, diffraction-limited images at 3.5 µm (FWHM=0.24'') and 4.8 µm (FWHM=0.33'') of the central arcsec region. These observations reveal the presence of an unresolved core (radius less than 8 pc at Half Maximum) and an 80 pc sized ``disc-like'' str…
Observation of the origin of CMEs in the low corona
Delaboudinière, J. -P.; Lamy, P.; Delannée, C.
The aim of the main observing program with EIT on board SOHO, is to monitor the whole Sun surface in the Fe xii emission line at 195 Ä, every 17 minutes. The very beginning of some CMEs can be observed. We interpret Fe xii images in conjunction with He ii, Hα and coronagraph observations over a period of 6 days. We find that 7 prominences produced…