Navegação Ciências Exatas e da Terra por Assunto "Abundancia"
Resultados 1-11 de 11
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Ages and metallicities of m31 star clusters
(1992) [Artigo de periódico]We present spectrophotometric data for 7 globular clusters and 2 open clusters in M31. The wide wavelength range available allows one to derive with confidence reddening, metallicity and age. It appears that the foreground ... -
CCD imaging of NGC 4861 : ionized gas properties and stellar formation
(1994) [Artigo de periódico]This work undertakes the study of the galaxy NGC 4861, using imaging centered at the strong lines Hα, Hβ, [O III] λ5007 and nearby continua. Integrated, absolute fluxes of 28 H II regions, and the region known as the bright ... -
Chemical abundance calibrations for the narrow-line region of active galaxies
(1998) [Artigo de periódico]We investigate two chemical abundance calibrations for the narrow-line region (NLR) of active galaxies in terms of three easily observable optical emission-line ratios, namely, [O III] λλ4959, 5007/Hβ; [N II] λλ6548, ... -
High-resolution abundance analysis of two individual stars of the bulge globular cluster NCG 6553
(1999) [Artigo de periódico]A detailed abundance analysis of 2 giants of the metal-rich bulge globular cluster NGC6553 was carried out using high resolution échelle spectra obtained at the ESO 3.6m telescope. The temperature calibration of metal-rich ... -
Mass loss from red giant stars in M67 : is there any evidence for a metallicity dependence?
(1996) [Artigo de periódico]Recent claims in the literature, that the rate of mass loss from red giant branch (RGB) stars in old, open clusters like M 67 and NGC 6791, increases with the metallicity above the value holding for Globular Clusters and ... -
Metallicity distribution of bulge globular clusters in M31
(1998) [Artigo de periódico]This paper presents 3600—5400 Å integrated spectra of 19 globular clusters (or candidates) projected on the central regions of M31, r ≤ 5.3' ( ≈ 1.2 kpc). We check the cluster nature of these objects, and derive their ages, ... -
A new hot DA white dwarf in a region of exceptionally low HI density
(1994) [Artigo de periódico]We report the discovery of the hot DA white dwarf RE 0457- 281 which has the lowest line-of-sight neutral hydrogen column density yet measured. The star was found independently by the ROSAT EUV, Montreal-Cambridge-Tololo ... -
NGC 6522 : an intermediate metallicity globular cluster projected on the baade window
(1994) [Artigo de periódico]We studied NGC 6522 colour magnitude diagrams using CCD photometry with BV filters. We have carefully estimated the reddening, which is criticai for Baade Window studies, obtaining E(B-V) = 0.55. We derive for this ... -
Spectrophotometry of globular clusters in NGC 5128 (centaurus a) : determination of their metallicities
(1996) [Artigo de periódico]We have carried out spectrophotometry in the range 3600–9700Å of five globular clusters in NGC 5128 for which previous photometric studies suggested a high metal content. We compare the equivalent widths of a set of metallic ... -
Super metal-rich clusters g158 and g177 in m31 : clues on the inner bulge/disc transition
(1992) [Artigo de periódico]The star clusters G 158 and G 177, located at projected distances smaller than 1.5 kpc from the semi-stellar nucleus of M 31, show spectra extreme in absorption-line strengths, comparable to those from the nuclei of giant ... -
VLT-UVES abundance analysis of four giants in NGC 6553
(2006) [Artigo de periódico]Context. Metal-rich globular clusters trace the formation of bulges. Abundance ratios in the metal-rich globular clusters such as NGC 6553 can constrain the formation timescale of the Galactic bulge. Aims. The purpose of ...