Abstract
Accretion disks can be eccentric: they support m = 1 modes that are global and slowly precessing. But whether the modes remain trapped in the disk - and hence are long-lived - depends on conditions at the outer edge of the disk. Here we show that in disks with realistic boundaries, in which the surface density drops rapidly beyond a given radius, eccentric modes are trapped and hence can live for as long as the viscous time. We focus on pressure-only disks around a central mass, and show how this result can be understood with the help of a simple second-order WKB theory. We show that the longest-lived mode is the zero-node mode in which all of the disk's elliptical streamlines are aligned, and that this mode decays coherently on the viscous timescale of the disk. Hence, such a mode, once excited, could live as long as the lifetime of the disk. It may be responsible for asymmetries seen in recent images of protoplanetary disks.
| Original language | English (US) |
|---|---|
| Article number | L11 |
| Journal | Astrophysical Journal Letters |
| Volume | 882 |
| Issue number | 1 |
| DOIs | |
| State | Published - Sep 1 2019 |
Fingerprint
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
}
Long-lived Eccentricities in Accretion Disks. / Lee, Wing Kit; Dempsey, Adam M.; Lithwick, Yoram.
In: Astrophysical Journal Letters, Vol. 882, No. 1, L11, 01.09.2019.Research output: Contribution to journal › Article
TY - JOUR
T1 - Long-lived Eccentricities in Accretion Disks
AU - Lee, Wing Kit
AU - Dempsey, Adam M.
AU - Lithwick, Yoram
PY - 2019/9/1
Y1 - 2019/9/1
N2 - Accretion disks can be eccentric: they support m = 1 modes that are global and slowly precessing. But whether the modes remain trapped in the disk - and hence are long-lived - depends on conditions at the outer edge of the disk. Here we show that in disks with realistic boundaries, in which the surface density drops rapidly beyond a given radius, eccentric modes are trapped and hence can live for as long as the viscous time. We focus on pressure-only disks around a central mass, and show how this result can be understood with the help of a simple second-order WKB theory. We show that the longest-lived mode is the zero-node mode in which all of the disk's elliptical streamlines are aligned, and that this mode decays coherently on the viscous timescale of the disk. Hence, such a mode, once excited, could live as long as the lifetime of the disk. It may be responsible for asymmetries seen in recent images of protoplanetary disks.
AB - Accretion disks can be eccentric: they support m = 1 modes that are global and slowly precessing. But whether the modes remain trapped in the disk - and hence are long-lived - depends on conditions at the outer edge of the disk. Here we show that in disks with realistic boundaries, in which the surface density drops rapidly beyond a given radius, eccentric modes are trapped and hence can live for as long as the viscous time. We focus on pressure-only disks around a central mass, and show how this result can be understood with the help of a simple second-order WKB theory. We show that the longest-lived mode is the zero-node mode in which all of the disk's elliptical streamlines are aligned, and that this mode decays coherently on the viscous timescale of the disk. Hence, such a mode, once excited, could live as long as the lifetime of the disk. It may be responsible for asymmetries seen in recent images of protoplanetary disks.
UR - http://www.scopus.com/inward/record.url?scp=85072614678&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85072614678&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ab3a4a
DO - 10.3847/2041-8213/ab3a4a
M3 - Article
AN - SCOPUS:85072614678
VL - 882
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - L11
ER -