Simón-Díaz, S.; García-Rojas, J.; Esteban, C.; Stasińska, G.; López-Sánchez, A. R.; Morisset, C.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 530, id.A57
Fecha de publicación:
6
2011
Revista
Número de citas
22
Número de citas referidas
21
Descripción
Aims: We have selected the Galactic H ii region M 43, a close-by
apparently spherical nebula ionized by a single star (HD 37061, B0.5 V)
to investigate several topics of recent interest in the field of H ii
regions and massive stars. In a series of two papers, we perform a
combined, comprehensive study of the nebula and its ionizing star by
using as many observational constraints as possible. Methods: We
collected for this study a set of high-quality observations, including
the optical spectrum of HD 37061, along with nebular optical imaging and
long-slit spatially resolved spectroscopy. The first part of our study
comprises a quantitative spectroscopic analysis of the ionizing star,
and the empirical analysis of the nebular images and spectroscopy. All
the information obtained here will be used to construct a customised
photoionization model of the nebula in Paper II. Results: We
determine the stellar parameters of HD 37061 and the total number of
ionizing photons emitted by the star. We find observational evidence of
scattered light from the Huygens region (the brightest part of the Orion
nebula) in the M 43 region. We show the importance of an adequate
correction of this scattered light in both the imagery and spectroscopic
observations of M 43 in accurately determining the total nebular
Hα luminosity, the nebular physical conditions. and chemical
abundances. We perform a detailed nebular empirical analysis of nine
apertures extracted from a long-slit located to the west of HD 37061
(east-west direction), obtaining the spatial distribution of the
physical conditions and ionic abundances. For three of the analyzed
elements (O, S, and N), we determine total abundances directly from
observable ions (no ionization correction factors are needed). The
comparison of these abundances with those derived from the spectrum of
the Orion nebula indicates the importance of the atomic data and,
specially in the case of M 42, the considered ionization correction
factors.
The INT and WHT telescopes are operated on the island of La Palma by the
RGO in the Spanish Roque de los Muchachos Observatory of the Instituto
de Astrofísica de Canarias.
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