Star formation history and chemical enrichment in the nuclear regions of m31 and its dwarf companions m32 and ngc 205
dc.contributor.author | Bica, Eduardo Luiz Damiani | pt_BR |
dc.contributor.author | Alloin, Danielle Marie | pt_BR |
dc.contributor.author | Schmidt, Alex Andre | pt_BR |
dc.date.accessioned | 2014-07-18T02:04:08Z | pt_BR |
dc.date.issued | 1990 | pt_BR |
dc.identifier.issn | 0004-6361 | pt_BR |
dc.identifier.uri | http://hdl.handle.net/10183/98029 | pt_BR |
dc.description.abstract | We 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.mimetype | application/pdf | pt_BR |
dc.language.iso | eng | pt_BR |
dc.relation.ispartof | Astronomy and Astrophysics. Berlin. Vol. 228, no. 1 (Feb. 1990), p. 23-26 | pt_BR |
dc.rights | Open Access | en |
dc.subject | Estruturas galaticas | pt_BR |
dc.subject | Galaxies: stellar content of | en |
dc.subject | Galaxies: nuclei of | en |
dc.subject | Evolucao galatica | pt_BR |
dc.subject | Galáxias | pt_BR |
dc.subject | Galaxies: evolution of | en |
dc.subject | Galaxies: M 31, M 32 and NGC 205 | en |
dc.subject | Nucleo galatico | pt_BR |
dc.subject | Astrofísica | pt_BR |
dc.title | Star formation history and chemical enrichment in the nuclear regions of m31 and its dwarf companions m32 and ngc 205 | pt_BR |
dc.type | Artigo de periódico | pt_BR |
dc.identifier.nrb | 000015280 | pt_BR |
dc.type.origin | Estrangeiro | pt_BR |
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