Unusual quiescent X-ray activity from XTE J0421+560 (original) (raw)

We report on BeppoSAX observations of the X-ray transient XTE J0421+560 in quiescence 156, 541, and ~690 days after the maximum of the 1998 April outburst. In the first observation the source was soft with a power-law photon index, alpha, of 4.0 ± 1.90.9 and absorption, NH, of (1.1 ± 4.91.1) × 1021 atom cm-2. In the second observation, the source brightened by a factor ~15 in the 1-10 keV energy range, became significantly harder with alpha = 1.86 ± 0.270.32 and was strongly absorbed with NH = (4.0 ± 0.8) × 1023 atom cm-2. There is evidence for a narrow emission line in both spectra at ~7 keV. In the third observation, the source had faded by a factor ⪆8 from the previous observation to below the BeppoSAX detection level. It is possible that these variations result from orbital motion of a compact object around the B[e] star companion with the intense, absorbed, spectrum arising during passage through dense circumstellar material. If this is the case, the system may be continuin...