The evolution of photo-evaporating viscous discs in binaries
G. Rosotti, and C. Clarke. (2017)cite arxiv:1710.08920Comment: 12 pages, 9 figures; accepted on MNRAS.
Abstract
A large fraction of stars are in binary systems, yet the evolution of
proto-planetary discs in binaries has been little explored from the theoretical
side. In this paper we investigate the evolution of the discs surrounding the
primary and secondary components of binary systems on the assumption that this
is driven by photoevaporation induced by X-rays from the respective star. We
show how for close enough separations (20-30 AU for average X-ray luminosities)
the tidal torque of the companion changes the qualitative behaviour of disc
dispersal from inside out to outside in. Fewer transition discs created by
photoevaporation are thus expected in binaries. We also demonstrate that in
close binaries the reduction in viscous time leads to accelerated disc clearing
around both components, consistent with $unresolved$ observations.
When looking at the $differential$ disc evolution around the two
components, in close binaries discs around the secondary clear first due to the
shorter viscous timescale associated with the smaller outer radius. In wide
binaries instead the difference in photo-evaporation rate makes the secondaries
longer lived, though this is somewhat dependent on the assumed scaling of
viscosity with stellar mass. We find that our models are broadly compatible
with the growing sample of $resolved$ observations of discs in
binaries. We also predict that binaries have higher accretion rates than single
stars for the same disc mass. Thus binaries probably contribute to the observed
scatter in the relationship between disc mass and accretion rate in young
stars.
Description
The evolution of photo-evaporating viscous discs in binaries
%0 Generic
%1 rosotti2017evolution
%A Rosotti, Giovanni P.
%A Clarke, Cathie J.
%D 2017
%K disks multiplicity
%T The evolution of photo-evaporating viscous discs in binaries
%U http://arxiv.org/abs/1710.08920
%X A large fraction of stars are in binary systems, yet the evolution of
proto-planetary discs in binaries has been little explored from the theoretical
side. In this paper we investigate the evolution of the discs surrounding the
primary and secondary components of binary systems on the assumption that this
is driven by photoevaporation induced by X-rays from the respective star. We
show how for close enough separations (20-30 AU for average X-ray luminosities)
the tidal torque of the companion changes the qualitative behaviour of disc
dispersal from inside out to outside in. Fewer transition discs created by
photoevaporation are thus expected in binaries. We also demonstrate that in
close binaries the reduction in viscous time leads to accelerated disc clearing
around both components, consistent with $unresolved$ observations.
When looking at the $differential$ disc evolution around the two
components, in close binaries discs around the secondary clear first due to the
shorter viscous timescale associated with the smaller outer radius. In wide
binaries instead the difference in photo-evaporation rate makes the secondaries
longer lived, though this is somewhat dependent on the assumed scaling of
viscosity with stellar mass. We find that our models are broadly compatible
with the growing sample of $resolved$ observations of discs in
binaries. We also predict that binaries have higher accretion rates than single
stars for the same disc mass. Thus binaries probably contribute to the observed
scatter in the relationship between disc mass and accretion rate in young
stars.
@misc{rosotti2017evolution,
abstract = {A large fraction of stars are in binary systems, yet the evolution of
proto-planetary discs in binaries has been little explored from the theoretical
side. In this paper we investigate the evolution of the discs surrounding the
primary and secondary components of binary systems on the assumption that this
is driven by photoevaporation induced by X-rays from the respective star. We
show how for close enough separations (20-30 AU for average X-ray luminosities)
the tidal torque of the companion changes the qualitative behaviour of disc
dispersal from inside out to outside in. Fewer transition discs created by
photoevaporation are thus expected in binaries. We also demonstrate that in
close binaries the reduction in viscous time leads to accelerated disc clearing
around both components, consistent with $\textit{unresolved}$ observations.
When looking at the $\textit{differential}$ disc evolution around the two
components, in close binaries discs around the secondary clear first due to the
shorter viscous timescale associated with the smaller outer radius. In wide
binaries instead the difference in photo-evaporation rate makes the secondaries
longer lived, though this is somewhat dependent on the assumed scaling of
viscosity with stellar mass. We find that our models are broadly compatible
with the growing sample of $\textit{resolved}$ observations of discs in
binaries. We also predict that binaries have higher accretion rates than single
stars for the same disc mass. Thus binaries probably contribute to the observed
scatter in the relationship between disc mass and accretion rate in young
stars.},
added-at = {2017-10-26T23:16:58.000+0200},
author = {Rosotti, Giovanni P. and Clarke, Cathie J.},
biburl = {https://www.bibsonomy.org/bibtex/2f8613e53e9f3b0112ac6b43e9ffb2974/superjenwinters},
description = {The evolution of photo-evaporating viscous discs in binaries},
interhash = {33653b10111217761b4a3021e83160b7},
intrahash = {f8613e53e9f3b0112ac6b43e9ffb2974},
keywords = {disks multiplicity},
note = {cite arxiv:1710.08920Comment: 12 pages, 9 figures; accepted on MNRAS},
timestamp = {2017-10-26T23:16:58.000+0200},
title = {The evolution of photo-evaporating viscous discs in binaries},
url = {http://arxiv.org/abs/1710.08920},
year = 2017
}