Lucio M. Buson

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Context. Systems of shells and polar rings in early-type galaxies are considered ”bona fide” tracers of mass accretion and/or mergers. Their high frequency in low density environments suggests that such episodes could drive the evolution of at least a fraction of the early-type galaxy population. Aims. We aim to cast light on the star formation histories of(More)
We have obtained high resolution UV images with the HST+WFPC2 of the central region of the dwarf elliptical galaxy NGC 205. Our images reveal that many of the hot UV stars previously detected and studied from the ground are actually multiple systems, open clusters and star associations. We have performed photometry of two such clusters and we find our data(More)
The mid infrared emission of early type galaxies traces the presence of intermediate age stellar populations as well as even tiny amounts of ongoing star formation. Here we discuss high S/N Spitzer IRS spectra of a sample of Virgo early type galaxies, with particular reference to NGC 4435. We show that, by combining mid infrared spectroscopic observations(More)
We use 16 μm, Spitzer-IRS, blue peakup photometry of 50 early-type galaxies in the Coma cluster to define the mid-infrared colour-magnitude relation. We compare with recent simple stellar population models that include the mid-infrared emission from the extended, dusty envelopes of evolved stars. The Ks-[16] colour in these models is very sensitive to the(More)
As part of the European Supernova Collaboration we obtained extensive photometry and spectroscopy of the type Ia SN 2002dj covering epochs from 11 days before to nearly two years after maximum. Detailed optical and near-infrared observations show that this object belongs to the class of the high-velocity gradient events as indicated by Si, S and Ca lines.(More)
NGC 5018, a relatively near, giant E3 galaxy, deserved quite a large attention in the past. Evidence of past interaction with other systems comes mainly from the extended pattern of dust lanes/patches clearly recognizable from ground-based observations. What is more, this object captures immediately the attention of the observer for (i) its anomalous(More)
We are performing a systematic study of the properties of earlytype galaxies in the mid infrared spectral region with the Spitzer Space Telescope. We present here high S/N Spitzer IRS spectra of 17 Virgo early-type galaxies. Thirteen objects of the sample (76%) show a pronounced broad feature (above 10μm) which is spatially extended and likely of stellar(More)
The average flux decrement shortward the Lyα emission, due to the well-known “forest” of absorptions, has been measured in the spectra of 8 quasars. Quasi-simultaneous optical and IUE observations of the two low redshift quasars PKS 0637–75 (z=0.654) and MC 1104+16 (z=0.632) have been carried out, obtaining relatively high S/N, spectrophotometrically(More)
We discuss the observational evidences of the morphological transformation of Spirals into S0 galaxies in the cluster environment exploiting two big databases of galaxy clusters: WINGS (0.04 < z < 0.07) and EDisCS (0.4 < z < 0.8). The most important results are: (1) the average number of S0 galaxies in clusters is almost a factor of ∼ 3− 4 larger today than(More)
The nucleus of the bulge-dominated, multiply-barred S0/a galaxy NGC 2681 is studied in detail, using high resolution Hubble Space Telescope FOC and NICMOS imaging and FOS spectroscopy. The ionised gas central velocity dispersion is found to increase by a factor ≈ 2 when narrowing the aperture from R ≈ 1. 5 (ground) to R ≈ 0. 1 (FOS). Dynamical modeling of(More)