The striking case of RX J1856.5-3754
n500 ks
DDT Chandra exposure
(i) RX J1856.5-3754 has a featureless X-ray continuum
(ii) better fit with a simple bb than with more sophisticated atmospheric models (Burwitz et al 2001, Drake et al 2002, Burwitz et al, 2002)
XMM-Newton and Chandra
spectra of RXJ1856
together with the best single
blackbody fit to each instrument (see table).