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dc.contributor.authorCalzetti, Danielapt_BR
dc.contributor.authorMeurer, Gerhardt R.pt_BR
dc.contributor.authorBohlin, Ralph C.pt_BR
dc.contributor.authorGarnett, Donald R.pt_BR
dc.contributor.authorKinney, Anne Louisept_BR
dc.contributor.authorLeitherer, Clauspt_BR
dc.contributor.authorStorchi-Bergmann, Thaisapt_BR
dc.date.accessioned2014-12-04T02:13:45Zpt_BR
dc.date.issued1997pt_BR
dc.identifier.issn0004-6256pt_BR
dc.identifier.urihttp://hdl.handle.net/10183/107734pt_BR
dc.description.abstractUltraviolet and optical narrow and broad band images of NGC 5253 obtained with the Hubble Space Te/escape Wide Field and Planetary Camera 2 are used to derive the properties of the dust distribution and the recent star formation history of this metal-poor dwarf galax.y. Corrections for the effects of dust are important in the center of NGC 5253: dust reddening is markedly inhomogeneous across the galaxy's central 20" region. One of the most obscured regions coincides with the region of highest star formation activity in the galax.y; clouds of more than 9 mag of optical depth at V enshroud a 2.5 Myr old stellar cluster in this area. The ages of the bright clusters in the center of the galax.y are anticorrelated with the amount of dust obscuration the cluster suffers. This result agrees with the expectation that young stellar associations are Iocated in heavily obscured regions, but after only 2-3 Myr they remove/emerge from the parental dust cloud and become almost extinction-free. On average, the continuum emission of the diffuse stellar population is about a factor of 2 less reddened than the ionized gas emission, a behavior typical of starburst galax.ies (Calzetti et al. 1994, ApJ, 429, 582). In the case of NGC 5253, this difference originares from the larger scale length of the star distribution relative to the ionized gas: the half light radius of the UV-bright stars is about twice as large as the half light radius of the ionized gas emission. Star formation has been active at least over the past 100 Myr in the central 20" of the galax.y, as indicated by the age distribution of both the blue diffuse stellar population and the bright stellar clusters. The star formation episodes may have been discrete in time, or almost continuous but variable in intensity and spatial extension. The current peak of the star formation is located in a 6" region, more spatially concentrated than the star formation averaged over the past 100 Myr. Its average star formation intensity is 10-5 -10-4 M8/yr/pc² for a 0.1-100 M8 Salpeter IMF, a factor of 10 to 100 times larger than in the galaxy's central 20". This starburst region contains a stellar population 5 Myr old and the two youngest (2.5 Myr and 3-4 Myr, respectively) of the bright stellar clusters in the galax.y's center. The two clusters contribute between 20% and 65% of the ionizing photons in the starburst, a contribution between 1.3 and 4.3 times larger than the average over the central 20". This is expected if cluster formation is an important mode of star formation in the early phase of a starburst event. The mass of the 2.5 Myr old cluster may be as large as 10 6 M8 , making this one a Super-Star-Cluster candidate. © 1997 American Astronomical Society. [S0004-6256(97)01411-8]en
dc.format.mimetypeapplication/pdf
dc.language.isoengpt_BR
dc.relation.ispartofThe Astronomical Journal. New York. Vol. 114, no. 5 (Nov. 1997), p. 1834-1849pt_BR
dc.rightsOpen Accessen
dc.subjectAstronomiapt_BR
dc.subjectSistemas solarespt_BR
dc.subjectAstrofisicapt_BR
dc.titleDust and recent star formation in the core of ngc 5253pt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb000152385pt_BR
dc.type.originEstrangeiropt_BR


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