Bibcode
Rodríguez, M.
Referencia bibliográfica
Astronomy and Astrophysics, v.351, p.1075-1086 (1999)
Advertised on:
11
1999
Revista
Número de citas
30
Número de citas referidas
25
Descripción
An analysis of CCD spectra in the range lambda lambda4200 -8775,
obtained at several positions of seven bright Galactic H Ii regions,
with galactocentric distances in the range 6-10 kpc, is presented.
Temperatures, densities and ionic abundances are calculated for all the
positions, and the relative trends followed by these parameters are
established. It is shown that all these H Ii regions share the same
abundances of element{O}, element{S}, element{Cl}, element{N},
element{Ar} and element{He}, within their expected uncertainties, a
result which is consistent with a flat or small abundance gradient in
the Galactic disc within +/-2 kpc from the Sun, as suggested by some
studies of the abundances in H Ii regions and B-type stars. The same set
of homogeneously derived ionic abundances is also used to test the
accuracy of the fractional ionization predicted by available grids of
models for photoionized nebulae. Based on observations made with the
Isaac Newton Telescope, operated on the island of La Palma by the Isaac
Newton Group in the Spanish Observatorio del Roque de los Muchachos of
the Instituto de Astrofísica de Canarias.