The observed orbits show that the common envelope was either very rapidly expelled or somehow avoided. During a poorly understood phase of strong interaction, the system did not suffer the dramatic spiral-in phase that is predicted for a common envelope evolution. The global picture that emerges from the observed orbital elements is that a star evolved in a system which is too short to accommodate a full-grown red giant branch (RGB) or AGB star 1. Their typical orbital periods are between a hundred and a few thousand days with, at times, surprisingly high eccentricities (up to e ~ 0.6). Subsequent systematic radial velocity monitoring campaigns focusing on stars surrounded by a disk showed that these systems were indeed mainly binaries ( Oomen et al. The observational characteristics of these objects were recently reviewed by Van Winckel (2018). By now, it has been well established that these SED characteristics point to the presence of a stable circumbinary disk of gas and dust in Keplerian rotation.
Historically, binaries located among post-asymptotic giant branch stars (post-AGB) have been serendipitously detected, however, they have also turned out to have a certain property in common, namely: a characteristic spectral energy distribution (SED) with a near- and mid-infrared excess pointing to the presence of hot dust in the system and a long-wavelength tail exhibiting a Rayleigh-Jeans slope.
#4peaks star meaning license#
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We argue that these disks are ideal for studying planet formation scenarios in an unprecedented parameter space. The question of whether such planets are first- or second-generation bodies also remains to be considered. If the planetary scenario is confirmed, disks around post-AGB binaries could be a unique laboratory for testing planet-disk interactions and their influence on the late evolution of binary stars. We advocate that giant planets can successfully explain the correlation between the transition disks and the depletion of refractory materials observed in post-AGB binaries. We propose two disk evolutionary scenarios, depending on the actual presence of such a giant planet in the disk.Ĭonclusions. We propose that such a mechanism is likely to be due to a giant planet carving a hole in the disk, effectively trapping the dust in the outer disk parts. We interpret this correlation as evidence of the presence of a mechanism that stimulates the dust and gas separation within the disk and that also produces the transition disk structure. We find a strong link between these transition disks and the depletion of refractory elements seen on the surface of the post-AGB star. Between 8 and 12% of our targets are surrounded by transition disks, that is, disks having no or low near-infrared excess. We categorized the different disk types and searched for correlations with other observational characteristics of these systems. We built a color-color diagram to differentiate between the different disk morphologies traced by the characteristics of the infrared excess. We compiled spectral energy distributions of 85 Galactic post-AGB binary systems. We explore the correlations between the different observables with the aim of learning more about potential disk-binary interactions. We assembled a catalog of all known Galactic post-AGB binaries featuring disks. Post-asymptotic giant branch (post-AGB) binaries are surrounded by massive disks of gas and dust that are similar to the protoplanetary disks that are known to surround young stars.Īims. SRON Netherlands Institute for Space Research,Ĭontext. Observatorio Astronómico Nacional (OAN-IGN),
Institute of Astronomy, KU Leuven, Celestijnenlaan 200D,Į-mail: of Physics and Astronomy, Macquarie University,Īstronomy, Astrophysics and Astrophotonics Research Centre, Macquarie University,
Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes
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