GS100-02-41: a new large HI shell in the outer part of the Galaxy
  Massive stars have a profound effect on the surrounding interstellar medium.
They ionize and heat the neutral gas, and due to their strong winds, they swept
the gas up forming large HI shells. In this way, they generate a dense shell
where the physical conditions for the formation of new stars are given. The aim
of this study is to analyze the origin and evolution of the large HI shell
GS100-02-41 and its role in triggering star forming processes.To characterize
the shell and its environs, we carry out a multi-wavelength study. We analyze
he HI 21 cm line, the radio continuum, and infrared emission distributions. The
analysis of the HI data shows an expanding shell structure centred at (l, b) =
(100.6 deg, -2.04 deg) in the velocity range from -29 to -51.7 km/s.
  We infer for GS100-02-41, a kinematical distance of 2.8 +/- 0.6 kpc. Several
massive stars belonging to Cep OB1 are located in projection within the large
HI, shell boundaries. The analysis of the radio continuum and infrared data
reveal that there is no continuum counterpart of the HI shell. On the other
hand, three slightly extended radio continuum sources are observed in
projection onto the dense HI shell. From their flux density determinations we
infer that they are thermal in nature. An analysis of the HI emission
distribution in the environs of these sources shows, for each of them, a region
of low emissivity having a good morphological correlation with the ionized gas
in a velocity range similar to the one where GS100-02-41 is detected. The
origin of GS100-02-41 could have been mainly due to the action of the Cep OB1
massive stars located inside the HI shell. The obtained age difference between
the HI shell and the HII regions, together with their relative location, led us
to conclude that the ionizing stars could have been created as a consequence of
the shell evolution.
