Loading...
THE NUCLEUS OF THE PLANETARY NEBULA EGB 6 AS A POST-MIRA BINARY
Bond, Howard Robin, Ciardullo Esplin, Taran L. Hawley, Steven A. Liebert, James Munari, Ulisse
Bond, Howard
Robin, Ciardullo
Esplin, Taran L.
Hawley, Steven A.
Liebert, James
Munari, Ulisse
Citations
Altmetric:
Abstract
EGB 6 is a faint, large, ancient planetary nebula (PN). Its central star, a hot DAOZ white dwarf (WD), is a prototype of a rare class of PN nuclei associated with dense, compact emission-line knots. The central star also shows excess fluxes in both the near-infrared (NIR) and mid-infrared (MIR). In a 2013 paper, we used Hubble Space Telescope (HST) images to show that the compact nebula is a point-like source, located 0 16 (∼118 AU) from the WD. We attributed the NIR excess to an M dwarf companion star, which appeared to coincide with the dense emission knot. We now present new ground-based NIR spectroscopy, showing that the companion is actually a much cooler source with a continuous spectrum, apparently a dust-enshrouded low-luminosity star. New HST images confirm common proper motion of the emission knot and red source with the WD. The I-band, NIR, and MIR fluxes are variable, possibly on timescales as short as days. We can fit the spectral energy distribution (SED) with four blackbodies (the WD, a ∼1850 K NIR component, and MIR dust at 385 and 175 K). Alternatively, we show that the NIR/MIR SED is very similar to that of Class 0/I young stellar objects. We suggest a scenario in which the EGB 6 nucleus is descended from a wide binary similar to the Mira system, in which a portion of the wind from an AGB star was captured into an accretion disk around a companion star; a remnant of this disk has survived to the present time and is surrounded by gas photoionized by UV radiation from the WD.
Description
Date
2016-07-27
Journal Title
Journal ISSN
Volume Title
Publisher
American Astronomical Society
Collections
Files
Loading...
Bond_ApJ_2016.pdf
Adobe PDF, 6.14 MB
Research Projects
Organizational Units
Journal Issue
Keywords
Binaries, Visual-planetary nebulae, General-White dwarfs
Citation
Bond, H. E., Ciardullo, R., Esplin, T. L., Hawley, S. A., Liebert, J., & Munari, U. (2016). The Nucleus Of The Planetary Nebula Egb 6 As A Post-Mira Binary. The Astrophysical Journal, 826(2), 139. doi:10.3847/0004-637x/826/2/139