Bibcode
DOI
Barth, Clarissa S.; Cepa, Jordi; Vilchez, Jose M.; Dottori, Horacio A.
Referencia bibliográfica
Astronomical Journal (ISSN 0004-6256), vol. 108, no. 6, p. 2069-2077
Fecha de publicación:
12
1994
Número de citas
16
Número de citas referidas
15
Descripción
This work undertakes the study of the galaxy NGC 4861, using imaging
centered at the strong lines H-alpha, H-beta, (O III) lambda 5007 and
nearby continua. Integrated, absolute fluxes of 28 H II regions, and the
region known as the bright knot, have been measured showing correlations
between the equivalent width of H-beta and the excitation index log ((O
III)/H-beta). An excitation gradient has been detected along the chain
of H II regions extending northwards from the bright knot, which is
unusual for irregular galaxies like NGC 4861. We suggest that this
gradient is due to different stages of evolution, or ages, of the H II
regions. The continuum fluxes of eight emissionless associations and the
continuum colors of the companion galaxy IC 3961 have also been
measured, and the presence of ionized gas cannot be detected. The age
and mass of the stellar population and ionizing stars of the bright knot
were subsequently estimated. It was also verified that this region is
the most important burst of star formation in NGC 4861.