Planetary nebulae are the glowing shells of gas and dust surrounding newly emerged white dwarf
stars. As described in a Nature Astronomy Review by researchers from the Instituto de
Astrofísica de Canarias (IAC) and the European Southern Observatory (ESO), the formation of
their highly aspherical structures can currently only be understood in the context of a binary
star scenario, where the influence of a companion star helps shape the mass lost by the nebula
progenitor.
Abell 63 was the first planetary nebula to be shown to host a binary central star, and has
since been shown to be an archetype system. This image taken with the WFC shows the nebula
to comprise a central barrel-shaped structure along with two caps of emission ejected along the
major axis of the central nebula. These caps have since been shown to be older than the
central regions by around 1000 years, probably forming via an episode of mass transfer between
the two stars at the nebular centre before the central barrel was itself ejected. Further
evidence for this mass transfer was discovered by combining observations from the Jacobus
Kapteyn Telescope and the William Herschel Telescope to show that the companion star in this
system has been inflated to nearly twice its normal size. This inflation is almost certainly a
result of the rapid mass transfer from the primary star knocking the companion out of thermal
equilibrium.
In recent years, it has become clear that the aforementioned properties of Abell 63 and its
central stars are shared by a great many other planetary nebulae with binary, and may hold the
key to understanding the exact role that binary interactions play in forming the plethora of
shapes observed among planetary nebulae.
More information:
D. Jones and H.M.J. Boffin, 2017, "Binary stars as the key to understanding planetary nebulae", Nature Astronomy, 1, 0117 [ Nature ]
S.A. Bell, D.L. Pollacco and R.W. Hilditch, 1994, "Direct optical observations of the secondary component of UU Sagittae", MNRAS, 270, 449-456 [ ADS ].
Contact:
Javier Méndez
(Public Relations Officer)
Source: Isaac Newton Group of Telescopes
