Volume 510, February 2010
|Number of page(s)||8|
|Published online||10 February 2010|
GAPHE, Département AGO, Université de Liège, Allée du 6 Août 17, Bât. B5C, 4000-Liège, Belgium e-mail: email@example.com
2 Department of Physics, Morrisville State College, Morrisville, NY 13408, USA
Accepted: 16 November 2009
High-energy emissions are good indicators of peculiar behaviours in stars. We have therefore obtained an XMM-Newton observation of HD 155806 and 1RXS J171502.4-333344, and derived their spectral properties for the first time. The X-ray spectrum of HD 155806 appears soft, even slightly softer than usual for O-type stars (as shown by a comparison with the O9 star HD 155889 in the same XMM-Newton 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 ( = -6.75). The high-resolution spectrum, though noisy, reveals a few broad, symmetric X-ray lines ( km s-1). 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. 1RXS J171502.4-333344 is a nearby flaring source of moderate X-ray luminosity ( = -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.
Key words: X-rays: stars / stars: early-type / stars: individual: 1RXS J171502.4-333344 / stars: individual: HD 155806 / stars: emission-line, Be / X-rays: individuals: HD 155889
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.