Search Publications
Age and metallicity gradients in the Galactic Bulge. A differential study using HST/WFPC2
Gilmore, G.; Feltzing, S.
The Galactic Bulge has long been assumed to be a largely old stellar population. However, some recent studies based on observations with the HST WF/PC-1 and WFPC2 of stars in the Galactic Bulge have concluded that the old population may not make up more then 30% of the total. Other studies using HST/WFPC2 differential studies of `Bulge' globular c…
A high-resolution study of episodic mass loss from the carbon star TT Cygni
Eriksson, K.; Gustafsson, B.; Olofsson, H. +3 more
CO radio line observations with the IRAM Plateau de Bure interferometer show that the carbon star TT Cyg is surrounded by a large (radius ~ 35arcsec or 2.7x1017 cm), geometrically thin (average width ~ 2farcs 5 or 1.9x1016 cm) shell of gas, which has a remarkable overall spherical symmetry (e.g., its radius varies by less tha…
The composition of the circumstellar dust around the Herbig Ae stars AB Aur and HD 163296
Waters, L. B. F. M.; de Koter, A.; van den Ancker, M. E. +1 more
We have analysed the 2-200 µm ISO spectra of two bright Herbig Ae stars, AB Aur and HD 163296, in order to derive the composition and mass over temperature distribution of the circumstellar dust. We find that the two stars have a similar composition of the dust, however also with some important differences. We address the onset of the strong…
Local galactic kinematics from Hipparcos proper motions
Mignard, F.
The stellar velocity field within two kiloparsecs of the solar system is investigated from the Hipparcos proper motions and parallaxes of about 20 000 single stars farther than 100 pc. The motion of the sun relative to the Local Standard of Rest and the relative systematic velocity field due to the galactic rotation are studied simultaneously for …
LMC and SMC Cepheids: combining bt OGLE with bt DENIS and bt 2MASS infrared data
Groenewegen, M. A. T.
I cross-correlate the ogle database of Cepheids in the Large and Small Magellanic Clouds (MCs) with the second incremental release of the 2mass JHKs survey, and the denis IJKs point source catalog towards the MCs. Of the 3384 Cepheids in ogle in both Clouds, 1745 have a counterpart in the 2mass survey within an 1'' radius and…
The HST snapshot survey of the B2 sample of low luminosity radio-galaxies: a picture gallery
Capetti, A.; Morganti, R.; de Ruiter, H. R. +3 more
A Hubble Space Telescope snapshot survey of the B2 sample of low luminosity radio galaxies has, at present, produced V and I images of 41 objects. Together with 16 images of B2 sources taken from the HST archive, there are now high resolution optical data for ~ 57% of the sample. All host galaxies are luminous ellipticals, except one which is a sp…
Detection of the extra-Galactic background fluctuations at 170 mu m
Lagache, G.; Puget, J. L.
We have used the Marano1 field observations with ISOPHOT at 170 mu m to search for the Cosmic Far-InfraRed Background fluctuations. This field is part of the FIRBACK project (Puget et al. 1999). For the first time, fluctuations due to unresolved extra-Galactic sources are isolated. The emission of such sources clearly dominates, at arcminute scale…
The ortho:para-H_2 ratio in C- and J-type shocks
Pineau des Forêts, G.; Cabrit, S.; Flower, D. R. +1 more
We have computed extensive grids of models of both C- and J-type planar shock waves, propagating in dark, cold molecular clouds, in order to study systematically the behaviour of the ortho:para-H_2 ratio. Careful attention was paid to both macroscopic (dynamical) and microscopic (chemical reactions and collisional population transfer in H_2) aspec…
Mid-infrared ISO spectroscopy of NGC 4945
Lutz, D.; Tielens, A. G. G. M.; Moorwood, A. F. M. +2 more
We have observed the central region of the nearby starburst galaxy NGC 4945 with the mid-infrared spectrometers SWS and PHT-S aboard ISO. We do not find any evidence for the existence of the powerful AGN, inferred from hard X-ray observations. The upper limits on our AGN tracers [ion {Ne}{v}] 14.32 mu m&24.3 mu m and [ion {Ne}{vi}] 7.65 mu m i…
Infrared imaging and spectroscopy of the Luminous Blue Variables Wra 751 and AG Car
Waters, L. B. F. M.; Morris, P. W.; Barlow, M. J. +6 more
We present ground-based infrared imaging and ISO spectroscopy of the luminous blue variables Wra 751 and AG Car. The images show in both cases a detached shell with a roughly circular distribution of emission. The infrared images of AG Car coincide very well with the optical images. The optical (Hα ) image of Wra 751 is different from the infrared…