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Abstract We report on the detection and analysis of extended X-ray emission by the Chandra X-ray Observatory stemming from the 2006 eruption of the recurrent nova RS Oph. The extended emission was detected 1254 and 1927 days after the start of the 2006 eruption and is consistent with a bipolar flow oriented in the East–West direction of the sky with opening angles of approximately 70°. The length of both lobes appeared to expand from 1.″3 in 2009 to 2.″0 in 2011, suggesting a projected expansion rate of 1.1 ± 0.1 mas day −1 and an expansion velocity of 4600 km s −1 ( D /2.4 kpc) in the plane of the sky. This expansion rate is consistent with previous estimates from optical and radio observations of material in a similar orientation. The X-ray emission does not show any evidence of cooling between 2009 and 2011, consistent with free expansion of the material. This discovery suggests that some mechanism collimates ejecta away from the equatorial plane, and that after that material passes through the red giant wind, it expands freely into the cavity left by the 1985 eruption. We expect similar structures to arise from the latest eruption and to expand into the cavity shaped by the 2006 eruption. 

RV Tau variables are a subclass of post-Asymptotic Giant Branch stars in binary systems surrounded by a circumbinary disk. Their signature light curves display alternating deep and shallow minima due to pulsations. The RVb-type subset exhibits an additional longer brightness modulation due to disk occultation. It has been established that binarity plays a key role in the dynamics and evolution of this short-lived post-AGB phase however the interconnection of the different physical components in these systems is still not well understood. We present multiwavelength observations of the prototypical RVb variable U Mon (mean Vmag ~6.4; D ~1 kpc)from XMM-Newton, SMA, DASCH, and AAVSO. U Mon has a pulsation period of 91.48 days and a longer brightness modulation period of 2451 days, consistent with the radial-velocity binary orbital period. We estimated the mass of the binary and the orbital semi-major axis which is consistent with the interaction of the binary with the inner edge of the circumbinary disk. U Mon hosts a 10 G magnetic field at its stellar surface which may be linked to X-rays detected by XMM-Newton. The X-ray emission is characteristic of a hot plasma (10 MK) with L/L~10. Based on our SMA observations, U Mon has a highly-inclined extended disk. From U Mon's combined DASCH and AAVSO data, there is evidence that U Mon has an even longer trend possibly due to inner-disk precession. We predict that the next deepest long-term minimum will be within the next decade.