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The transient X-ray source SAX J2239.3+6116 and its optical counterpart

J. J. M. in 't Zand·J. Halpern·M. Eracleous·M. McCollough·T. Augusteijn·R. A. Remillard·J. Heise
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Abstract

We have discovered with the Wide Field Cameras on board BeppoSAX the weak transient X-ray source SAXJ2239.3+6116 whose position coincides with that of 4U2238+60/3A2237+608 and is close to that of the fast transient AT2238+60 and the unidentified EGRET source 3EG2227+6122. The data suggest that the source exhibits outbursts that last for a few weeks and peak to a flux of 4E-10 erg/s/cm2 (2-10 keV) at maximum. During the peak the X-ray spectrum is hard with a photon index of -1.1+/-0.1. Follow-up observations with the Narrow-Field Instruments on the same platform revealed a quiescent emission level that is 1E+3 times less. Searches through the data archive of the All-Sky Monitor on RXTE result in the recognition of five outbursts in total from this source during 1996-1999, with a regular interval time of 262 days. Optical observations with the KPNO 2.1 m telescope provide a likely optical counterpart. It is a B0 V to B2 III star with broadened emission lines at an approximate distance of 4.4 kpc. The distance implies a 2-10 keV luminosity in the range from 1E+33 to 1E+36 erg/s. The evidence suggests that SAXJ2239.3+6116 is a Be X-ray binary with an orbital period of 262 days.

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J. J. M. in 't Zand, J. Halpern, M. Eracleous, M. McCollough, T. Augusteijn, R. A. Remillard, J. Heise. 2000-06-23. The transient X-ray source SAX J2239.3+6116 and its optical counterpart. https://arxiv.org/abs/astro-ph/0006335

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