Infall - crucial, yet underrated
Michael Küffmeier
C. P. Dullemond, F. Goicovic, S. Reißl, T. Haugbølle, Å. Nordlund
Stars are born and embedded in large assemblies of gas
Star-disk systems form and are located in different environments provided by Giant Molecular Clouds (Size: 10 - 100 pc)
Serpens SMM1 (Le Gouellec et al. 2019)
Zoom-in method
Küffmeier et al. 2017
- adaptive mesh refinement
- ideal magnetohydrodynamics
- turbulence driven by supernovae
- stars modelled as sink particles
Zoom-in on embedded protostellar multiple
Küffmeier, Reißl, Wolf et al. 2020
bridge structure similar to IRAS 16293--2422 (e.g. Sadavoy+ 2018, van der Wiel+ 2019, Maureira+ 2020)
Küffmeier et al.
2018/2019
Küffmeier et al.
2017
Heterogeneous accretion implies late infall
Observational indication: luminosity bursts (Padoan et al. 2014)
Zoom-in method
Küffmeier et al. 2017
- adaptive mesh refinement
- ideal magnetohydrodynamics
- turbulence driven by supernovae
- stars modelled as sink particles
Zoom-in on embedded protostars
Küffmeier et al.
2019
bridge structure similar to IRAS 16293--2422 (e.g. Sadavoy+ 2018, van der Wiel+ 2019, Maureira+ 2020)
Küffmeier, Reißl et al. 2020
~1500 AU
Küffmeier et al. 2018
Heterogeneous star formation
Küffmeier et al.
2018
Heterogeneous accretion implies late infall
Küffmeier et al.
2017
Observational indication: luminosity bursts
Late infall
AB Aurigae
HD 100546
Credit: Grady+ 1999, Fukagawa+ 2004
Can (late) infall cause misalignment of inner and outer disk?
Credit: Ardila+ 2007
200 au
HD 142527
Credit: Avenhaus+ 2014
Extended arc-like structures can be induced by late infall
(Dullemond, Küffmeier, Goicovic+ 2019, Küffmeier, Goicovic & Dullemond 2020)
Possibility of "second-generation" disk
Shadows due to misaligned inner and outer disk
Credit: Marino+ 2015
Simulate cloudlet infall onto disk
AREPO, pure hydrodynamical
R_{\rm i,d}=50\, \rm au
\Sigma(r) = 170 \left(\frac{\rm g}{\rm cm}\right)^{2} \left( \frac{r}{1 \rm au} \right)^{-3/2}
M_{\rm cloudlet}(R_{\rm cloudlet}) = 0.01 {\rm M}_{\odot} \left( \frac{R_{\rm cloudlet}}{5000 \rm au}\right)^{2.3}
R_{\rm cloudlet} = 887\, \rm au
isothermal gas
vary infalling angle
\alpha = 0^{\circ} (35^{\circ}, 60^{\circ}, 90^{\circ})
b = 1774\, \rm au
vary rotation (prograde, retrograde)
Küffmeier, Dullemond, Reißl, Goicovic + subm
M_{*}=2.5\, \mathrm{M}_{\odot}
Prograde vs. retrograde infall
Retrograde infall causes:
- counter-rotating inner and outer disk
- shrinking of inner disk
- enhanced accretion
- larger and deeper gap between disks
see also Vorobyov+ 2016
Effect of infall angle on disk
Formation of misaligned configuration
Observable as shadows in outer disk
Disk evolution: eccentricity
prograde, 0°
Light to dark: retrograde infall with increasing inclination
- mild eccentricity in inner disk (up to ~0.1)
inner
outer
- larger eccentricities in outer disk (0.2 to 0.4)
Infall triggers:
=> probably measurable with CO channel maps:
a test of infall scenario
Disclaimer:
We are not saying that all shadows are due to misaligned infall!
In some cases shadows have already been well explained by external companions and/or inner planets (e.g.: HD 100453 Gonzalez+ '20/Nealon+ '20 or work by Zhu '19 on planet-induced misalignment)
Infall mechanism in perspective
But we need to think out of the disk:
significant fraction of final mass might accrete later through inflow
(Pelkonen et al. 2020)
Per-emb-8 (Pineda+ '20); see also [BHB2007] 1 (Alves+ '20), IRS 63 (Segura-Cox+ in prep), FU Ori, Z CMa, V1735 Cyg, V1057 Cyg (Liu+ '16), Ágnes Kóspál's talk(?)
Küffmeier et al. 2019
Take-away points
In infall-induced misaligned systems, the outer disk is expected to have higher eccentricity than the inner disk.
Retrograde infall can cause counter-rotating disks, shrinking of inner disk, formation of gaps (>10 AU) and enhanced accretion.
Star formation is a heterogenous process with the possibility of late infall.
WIP: study synthetic observations of infall-induced shadows
RGB image of misaligned system forming from infall with 60°
blue (1.66 micron), green (53 micron), red (870 micron); Credit: S. Reißl
Accretion workshop
By kuffmeier
