Search Publications
Multiple shells in IRC+10216: shell properties
Mauron, N.; Huggins, P. J.
We report on the properties of the multiple shells in the circumstellar envelope of IRC+10216, using deep optical imaging, including data from the Hubble Space Telescope. The intensity profiles confirm the presence of thin ( ~ 0farcs5 -3'' ec), limb-brightened shells in the envelope, seen in stellar and ambient Galactic light scattered by dust. Th…
ISO-SWS observations of OMC-1: H_2 and fine structure lines
Bertoldi, F.; Drapatz, S.; Rosenthal, D.
Using the Short-Wavelength-Spectrometer on the Infrared Space Observatory (ISO), we obtained near- and mid-infrared spectra toward the brightest H_2 emission peak of the Orion OMC-1 outflow. A wealth of emission and absorption features were detected, dominated by 56 H_2 ro-vibrational and pure rotational lines reaching from H_2 0-0 S(1) to 0-0 S(2…
The anomalous Galactic globular cluster NGC 2808. Mosaic wide-field multi-band photometry
Zoccali, M.; Stetson, P. B.; Bedin, L. R. +4 more
We present Johnson UBV, and Kron-Cousins I photometry for about 60,000 stars in a region of 44x33 arcmin2 centered on the Galactic globular cluster (GGC) NGC 2808. The central r<100 arcsec region has been mapped also in the F218W, F439W, and F555W bands with the HST WFPC2 camera. Overall, we cover a field which extends from the cente…
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…
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…
Hα emitting galaxies and the cosmic star formation rate at z =~ 2.2
Oliva, E.; van der Werf, P. P.; Moorwood, A. F. M. +1 more
An infrared imaging survey in narrow band filters around 2.1 mu m has yielded ~ 10 candidate Hα emitting galaxies at z =~ 2.2 of which 6 have been subsequently confirmed spectroscopically with ISAAC at the ESO VLT. The survey reached a limiting line flux of ~ 5x10-17 erg cm-2 s-1 and covered 100 arcmin2 …
The HST view of the FR I / FR II dichotomy
Capetti, A.; Chiaberge, M.; Celotti, A.
In order to explore how the FR I / FR II dichotomy is related to the nuclear properties of radio galaxies, we studied a complete sample of 26 nearby FR II radio galaxies using Hubble Space Telescope (HST) images and compared them with a sample of FR I previously analyzed. FR I nuclei lie in the radio-optical luminosity plane along a tight linear c…
The cometary blue compact dwarf galaxies Mkn 59 and Mkn 71. A clue to dwarf galaxy evolution?
Thuan, T. X.; Izotov, Y. I.; Papaderos, P. +3 more
``Cometary'' Blue Compact Dwarf Galaxies (iI,C BCDs) are characterized by an off-center starburst close to the end of their elongated stellar bodies. This rare phenomenon may carry some clues on how collective star formation ignites and propagates in gas-rich low-mass stellar systems. This off-center burst may be a fortuitous enhancement of the ot…
The evolution of the color gradients of early-type cluster galaxies
Greggio, L.; Saglia, R. P.; Bender, R. +2 more
We investigate the origin of color gradients in cluster early-type galaxies to probe whether pure age or pure metallicity gradients can explain the observed data in local and distant (z ≈ 0.4) samples. We measure the surface brightness profiles of the 20 brightest early-type galaxies of CL0949+44 (hereafter CL0949) at redshift z=0.35-0.38 from HST…
The elusive active nucleus of NGC 4945
Maiolino, R.; Marconi, A.; Macchetto, F. +4 more
We present new HST NICMOS observations of NGC 4945, a starburst galaxy hosting a highly obscured active nucleus that is one of the brightest extragalactic sources at 100 keV. The HST data are complemented with ground based Fe II line and mid-IR observations. A 100pc-scale starburst ring is detected in Paα, while H2 traces the walls of a…