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arXiv · 0709.4366

X-Ray Eclipse Time Delays in 4U2129+47

E. Bozzo·M. Falanga·A. Papitto·L. Stella·R. Perna·D. Lazzati·G. Israel·S. Campana·V. Mangano·T. Di Salvo·L. Burderi
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Abstract

4U 2129+47 was discovered in the early 80's and classified as an accretion disk corona source due to its broad and partial X-ray eclipses. The 5.24 hr binary orbital period was inferred from the X-ray and optical light curve modulation, implying a late K or M spectral type companion star. The source entered a low state in 1983, during which the optical modulation disappeared and an F8 IV star was revealed, suggesting that 4U 2129+47 might be part of a triple system. The nature of 4U 2129+47 has since been investigated, but no definitive conclusion has been reached. Here, we present timing and spectral analyses of two XMM-Newton observations of this source, carried out in May and June, 2005. We find evidence for a delay between two mid-eclipse epochs measured ~22 days apart, and we show that this delay can be naturally explained as being due to the orbital motion of the binary 4U 2129+47 around the center of mass of a triple system. This result thus provides further support in favor of the triple nature of 4U 2129+47.

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E. Bozzo, M. Falanga, A. Papitto, L. Stella, R. Perna, D. Lazzati, G. Israel, S. Campana, V. Mangano, T. Di Salvo, L. Burderi. 2007-09-27. X-Ray Eclipse Time Delays in 4U2129+47. https://doi.org/10.1051/0004-6361:20078444

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