2000/05/30 by A. N. Parmar, T. Belloni, Parmar, A. N. +9
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0005565
4 pages. To appear in A&AL
arxiv created 2000/05/30 · openalex publication_date 2000/05/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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 of 4.0 (+1.9 -0.9) and absorption, NH, of (1.1 +4.9 -1.1) X 1021 atom/cm2. In the second observation, the source brightened by a factor ~15 in the 1-10 keV energy range, became significantly harder with a photon index of 1.86 (+0.27 -0.32) and was strongly absorbed with NH = (4.0 +/- 0.8) X 1023 atom/cm2. 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 continuing to exhibit periodic activity.