Hubble Space Telescope Imaging of the Expanding Nebular Remnant of the 2006 Outburst of the Recurrent Nova RS Ophiuchi

• Published in: The Astrophysical journal Vol. 665; no. 1; pp. L63 - L66
• Main Authors: Bode, M. F, Harman, D. J, O’Brien, T. J, Bond, Howard E, Starrfield, S, Darnley, M. J, Evans, A, Eyres, S. P. S
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 10.08.2007; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; White dwarf stars; white dwarfs; Supernovae; planetary nebulae: general; Cataclysmic variable stars; Planetary nebulae; stars: individual (RS Ophiuchi); supernovae: general; Recurrent novae; binaries: symbiotic; novae, cataclysmic variables
• ISSN: 1538-4357; 0004-637X; 1538-4357
• DOI: 10.1086/520929

We report Hubble Space Telescope imaging obtained 155 days after the 2006 outburst of RS Ophiuchi. We detect extended emission in both [O III] A5007 and [Ne v] A3426 lines. In both lines, the remnant has a double ring structure. The east-west orientation and total extent of these structures (580 plus or minus 50 All at d = 1.6 kpc) is consistent with that expected due to expansion of emitting regions imaged earlier in the outburst at radio wavelengths. Expansion at high velocity appears to have been roughly constant in the east-west direction ( [unk] = 3200 plus or minus 300 km s-1 in the plane of the sky), with tentative evidence of deceleration north-south. We present a bipolar model of the remnant whose Inclination is consistent with that of the central binary. The true expansion velocities of the polar components are then v = 5600 plus or minus 1100) km s-1. We suggest that the bipolar morphology of the remnant results from interaction of the outburst ejecta with a circumstellar medium that is significantly denser in the equatorial regions of the binary than at the poles. This is also consistent with observations of shock evolution in the X-ray and the possible presence of dust in the Infrared. Furthermore, it is in line with models of the shaping of planetary nebulae with close binary central systems, and also with recent observations relating to the progenitors of Type Ia supernovae, for which recurrent novae are a proposed candidate. Our observations also reveal more extended structures to the south and east of the remnant whose possible origin is briefly discussed.