  High-energy emissions are good indicators of peculiar behaviours in stars. We
have therefore obtained an XMM-Newton observation of HD155806 and
1RXSJ171502.4-333344, and derived their spectral properties for the first time.
The X-ray spectrum of HD155806 appears soft, even slightly softer than usual
for O-type stars (as shown by a comparison with the O9 star HD155889 in the
same XMM field). It is well-fitted with a two-component thermal model with low
temperatures (0.2 and 0.6 keV), and it shows no overluminosity
(log[LX/Lbol]=-6.75). The high-resolution spectrum, though noisy, reveals a few
broad, symmetric X-ray lines (FWHM ~ 2500 km/s). The X-ray emission is
compatible with the wind-shock model and therefore appears unaffected by the
putative dense equatorial regions at the origin of the Oe classification.
1RXSJ171502.4-333344 is a nearby flaring source of moderate X-ray luminosity
(log[LX/Lbol]=-3), with a soft thermal spectrum composed of narrow lines and
presenting a larger abundance of elements (e.g. Ne) with a high first
ionization potential (FIP) compared to lower-FIP elements. All the evidence
indicates a coronal origin for the X-ray emission, in agreement with the dMe
classification of this source.
