A&A 430, 541-548 (2005)
DOI: 10.1051/0004-6361:20041788
The ionizing star of the North America and Pelican nebulae
F. Comerón1 and A. Pasquali21 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
e-mail: fcomeron@eso.org
2 Institute of Astronomy, ETH Hoenggerberg, HPF, 8093 Zurich, Switzerland
e-mail: pasquali@phys.ethz.ch
(Received 4 August 2004 / Accepted 9 September 2004)
Abstract
We present the results of a search for the ionizing star
of the North America (NGC 7000) and the Pelican (IC 5070) nebulae
complex. The application of adequate selection criteria to the
2MASS
broad-band photometry allows us to narrow the search
down to 19 preliminary candidates in a circle of
radius containing most of the L935 dark cloud
that separates both nebulae. Follow-up
near-infrared spectroscopy shows that most of these objects are
carbon stars and mid-to-late-type giants, including some AGB
stars. Two of the three remaining objects turn out to be later
than spectral type B and thus cannot account for the ionization of
the nebula, but a third object, 2MASS J205551.25+435224.6, has
infrared properties consistent with it being a mid O-type star at
the distance of the nebulae complex and reddened by
. We confirm its O5V spectral type by means of visible
spectroscopy in the blue. This star has the spectral type required
by the ionization conditions of the nebulae and photometric
properties consistent with the most recent estimates of their
distance. Moreover, it lies close to the geometric center of the
complex that other studies have proposed as the most likely
location for the ionizing star, and is also very close to the
position inferred from the morphology of cloud rims detected in
radio continuum. Given the fulfillment of all the conditions and
the existence of only one star in the whole search area that
satisfies them, we thus propose 2MASS J205551.25+435224.6 as the
ionizing star of the North America/Pelican complex.
Key words: ISM: HII regions -- ISM: individual objects: NGC 7000 -- ISM: individual objects: IC 5070 -- ISM: individual objects: W80
SIMBAD Objects
© ESO 2005