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dc.contributor.authorBica, Eduardo Luiz Damianipt_BR
dc.contributor.authorAlloin, Danielle Mariept_BR
dc.contributor.authorSchmidt, Alex Andrept_BR
dc.date.accessioned2014-07-18T02:04:08Zpt_BR
dc.date.issued1990pt_BR
dc.identifier.issn0004-6361pt_BR
dc.identifier.urihttp://hdl.handle.net/10183/98029pt_BR
dc.description.abstractWe present a comparative discussion about the stellar population and chemical enrichment in the nuclear regions of M 31 and of its dwarf companions M 32 and NGC 205, from a new set of long slit CCD spectra in the range 3500-10 000 Å. We have performed the population syntheses using a grid of star cluster spectral features as a function of age and metallicity. The algorithm is a multiple minimization procedure, including a statistical treatment of the acceptable solutions and for which we discuss as well the question of the uniqueness of the solution. It provides a more significant result with respect to classical minimization methods relying on a single optimal solution. We find that the semistellar nucleus (SSN) and the bulge of M 31 are dominated by old metal-rich populations. The overall enrichment in heavy elements is however larger in the SSN ([Z/Zʘ ] ~ 0.6 at least) than in the inner bulge ([Z/Zʘ ] = 0.3). In the visible, flux fractions of 10 to 20% arise from an intermediate age component. The old age components span the entire metallicity range, with a predominant contribution from the highly metallic ones. The young age component remains inconspicuous in the visible range. In the nucleus of M 32, the metal enrichment comes out to be around solar and the light is dominated by old components in the range -0.5 < [Z/Zʘ ] <O. As much as 30% ofthe flux at 5870 Å arises from an intermediate age component corresponding to a 15% mass fraction. Both the old metal-poor and the young components in M 32 contribute very little to the visible flux. Finally, our synthesis shows that the dominant population in the nucleus of NGC 205 is young, in the range 10⁸ to 510⁸ yr. The old component with metallicity -1 < [Z/Zʘ ] < -0.5 and the intermediate age components provide each around 20% of the visible light. The maximum metallicity attained in this object is [Z/Zʘ ] = -0.5.en
dc.format.mimetypeapplication/pdf
dc.language.isoengpt_BR
dc.relation.ispartofAstronomy and Astrophysics. Berlin. Vol. 228, no. 1 (Feb. 1990), p. 23-26pt_BR
dc.rightsOpen Accessen
dc.subjectGalaxies: stellar content ofen
dc.subjectEstruturas galaticaspt_BR
dc.subjectEvolucao galaticapt_BR
dc.subjectGalaxies: nuclei ofen
dc.subjectGalaxies: evolution ofen
dc.subjectGaláxiaspt_BR
dc.subjectNucleo galaticopt_BR
dc.subjectGalaxies: M 31, M 32 and NGC 205en
dc.subjectAstrofisicapt_BR
dc.titleStar formation history and chemical enrichment in the nuclear regions of m31 and its dwarf companions m32 and ngc 205pt_BR
dc.typeArtigo de periódicopt_BR
dc.identifier.nrb000015280pt_BR
dc.type.originEstrangeiropt_BR


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