The occurrence of supergiants at high galactic latitudes has
  long been an enigma: how can massive stars reach such large
  distances from the galactic plane?
  The IRAS mission has detected IR excesses in many of these
  stars.  A new interpretation is then that they are not genuine
  massive stars, but rather low-mass stars in an advanced stage
  of evolution, presumably post-AGB.  Stars in this short phase
  of evolution had virtually not been found before IRAS.
  Still, for some high-latitude supergiants, no IR excess has
  been found so far.  PHOT observations will answer if this is
  just a matter of IRAS detection limit.  Failure of detecting
  IR excesses in these stars may reopen the question of massive
  star occurrence far from the galactic plane.
  The objects for which an IR excess is found, show a perplexing
  diversity in their appearances.  Mass loss histories appear to
  change from star to star, photospheric abundances often are not
  conform to expectation, peculiar emission features are observed
  in several stars.  Many turn out to be binaries: the suspicion
  arises that some of these stars actually are 'blue AGB stars',
  that underwent blueward evolution after mass transfer.
  SWS AOT01 observations will reveal in unprecedented detail the
  IR energy distribution and emission features of these stars.
  Modelling the energy distribution enables to enravel the mass
  loss history.  We focus on stars that are also bright in the
  optical and the UV: IR features can then be linked to
  photospheric abundances and possibly to circumstellar absorption
  features.
  This proposal is linked with the SWS central program proposal
  by Rens Waters.