P. Pedotti

Università degli Studi di Milano-Bicocca, Milano, Lombardy, Italy

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Publications (7)15.18 Total impact

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    ABSTRACT: We present the H$\alpha$ imaging observations of 273 late-type galaxies in the nearby rich galaxy clusters Virgo, A 1367, Coma, Cancer, Hercules and in the Great Wall, carried out primarily with the 2.1 m telescope of the San Pedro Martir Observatory (SPM) and with the ESO/3.6 m telescope. We derived the H$\alpha$+[NII] fluxes and equivalent widths. The H$\alpha$ survey reached completion for an optically selected sample of nearby galaxies in and outside rich clusters. Taking advantage of the completeness of the data set, the dependence of H$\alpha$ properties on the Hubble type was determined for late-type galaxies in the Virgo cluster. Differences in the gaseous content partly account for the large scatter of the H$\alpha$ EW within each Hubble-type class. We studied the radial distributions of the H$\alpha$ EW around Coma+A 1367 and the Virgo clusters in two luminosity bins. Luminous galaxies show a decrease in their average H$\alpha$ EW in the inner ~1 virial radius, while low-luminosity galaxies do not show this trend.
    Astronomy and Astrophysics 02/2006; DOI:10.1051/0004-6361:20053843 · 4.48 Impact Factor
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    ABSTRACT: We present the Halpha imaging observations of 273 late-type galaxies in the nearby rich galaxy clusters Virgo, A 1367, Coma, Cancer, Hercules and in the Great Wall, carried out primarily with the 2.1m telescope of the San Pedro Martir Observatory (SPM) and with the ESO/3.6m telescope. We derived the Halpha+[NII] fluxes and equivalent widths. The Halpha survey reached completion for an optically selected sample of nearby galaxies in and outside rich clusters. Taking advantage of the completeness of the data set, the dependence of Halpha properties on the Hubble type was determined for late-type galaxies in the Virgo cluster. Differences in the gaseous content partly account for the large scatter of the Halpha EW within each Hubble-type class. We studied the radial distributions of the Halpha EW around Coma+A 1367 and the Virgo clusters in two luminosity bins. Luminous galaxies show a decrease in their average Halpha EW in the inner ~1 virial radius, while low-luminosity galaxies do not show this trend. Description: (3 data files).
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    ABSTRACT: Halpha+[NII] imaging observations of 369 late-type (spiral) galaxies in the Virgo cluster and in the Coma/A1367 supercluster are analyzed, covering 3 rich nearby clusters (A1367, Coma and Virgo) and nearly isolated galaxies in the Great-Wall. They constitute an optically selected sample (mp
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    ABSTRACT: Halpha+[NII] imaging observations of 369 late-type galaxies in the Virgo cluster and in the Coma/A1367 supercluster are analyzed. They constitute an optically selected sample (m_p<16.0) observed with 60% c.a. completeness.These observations provide us with the current (T<10^7 yrs) star formation properties of galaxies. The expected decrease of the star formation rate (SFR),as traced by the Halpha E.W., with decreasing clustercentric projected distance is found only when galaxies brighter than M_p=-19.5 are considered. We also include in our analysis Near Infrared data, providing us with informations on the old (T>10^9yrs) stars. Put together, the young and the old stellar indicators give the ratio of currently formed stars over the stars formed in the past, or "birthrate" parameter b. We also determine the "global gas content" combining HI with CO observations. We define the "gas deficiency" parameter as the logarithmic difference between the gas content of isolated galaxies of a given Hubble type and the measured gas content.For the isolated objects we find that b decreases with increasing NIR luminosity. The gas-deficient objects, primarily members to the Virgo cluster, have their birthrate significantly lower than the isolated objects with normal gas content and of similar NIR luminosity. This indicates that the current star formation is regulated by the gaseous content of spirals.Whatever mechanism (most plausibly ram-pressure stripping) is responsible for the pattern of gas deficiency observed in spiral galaxies members to rich clusters, it also produces the observed quenching of the current star formation. Comment: 22 pages,14 figures,3 figures available in jpeg format.To be published in A&A
    Astronomy and Astrophysics 09/2002; 396(2). DOI:10.1051/0004-6361:20021403 · 4.48 Impact Factor
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    ABSTRACT: Halpha imaging observations of 125 galaxies obtained with the 2.1 m telescope of the San Pedro Martir Observatory (SPM) (Baja California, Mexico) are presented. The observed galaxies are mostly Virgo cluster members (77), with 36 objects in the Coma/A1367 supercluster and 12 in the clusters A2197 and A2199 taken as fillers. Halpha +[NII] fluxes and equivalent widths, as well as images of the detected targets are presented. The observatory of San Pedro Martir (Mexico) belongs to the Observatorio Astronómico Nacional, UNAM. Figure 4 is only available in electronic form at http://www.edpsciences.org
    Astronomy and Astrophysics 04/2002; 386(1):114-123. DOI:10.1051/0004-6361:20020214 · 4.48 Impact Factor
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    ABSTRACT: Optical spectroscopy of 76 galaxies, 48 of which are projected in the direction of the Virgo cluster and 28 onto the Coma-A1367 supercluster, is reported. Adding these new measurements to those found in the literature, the redshift completeness in the Virgo region becomes 92% at B_T<=16.0 and 68% at B_T<=18.0. The one of CGCG galaxies in the direction of the Coma-A1367 supercluster becomes 98%. The Virgo cluster membership estimates obtained on morphological grounds by Binggeli et al. (1985) are confirmed in all cases. However, several "possible members" classified as BCD (if in the cluster) are found instead to be giant emission-line galaxies in the background of the Virgo cluster
    Astronomy and Astrophysics Supplement Series 08/2000; DOI:10.1051/aas:2000270 · 1.75 Impact Factor

Publication Stats

61 Citations
15.18 Total Impact Points

Institutions

  • 2000–2006
    • Università degli Studi di Milano-Bicocca
      Milano, Lombardy, Italy
  • 2002
    • Universidad Nacional Autónoma de México
      Ciudad de México, Mexico City, Mexico