Two circumstellar nebulae discovered with the Wide-field Infrared Survey
  Explorer and their massive central stars
  We report the discovery of two mid-infrared nebulae in the northern
hemisphere with the Wide-field Infrared Survey Explorer and the results of
optical spectroscopy of their central stars, BD+60 2668 (composed of two
components, separated from each other by \approx 3 arcsec) and ALS 19653, with
the Calar Alto 3.5-m telescope and the Southern African Large Telescope (SALT),
respectively. We classify the components of BD+60 2668 as stars of spectral
types B0.5 II and B1.5 III. ALS 19653 is indicated in the SIMBAD data base as a
planetary nebula, while our observations show that it is a massive B0.5 Ib
star, possibly in a binary system. Using the stellar atmosphere code FASTWIND,
we derived fundamental parameters of the three stars as well as their surface
element abundances, implying that all of them are either on the main sequence
or only recently left it. This provides further evidence that massive stars can
produce circumstellar nebulae while they are still relatively unevolved. We
also report the detection of optical counterparts to the mid-infrared nebulae
and a second, more extended optical nebula around ALS 19653, and present the
results of SALT spectroscopy of both nebulae associated with this star. The
possible origin of the nebulae is discussed.
