The role of infall in (re-)orienting star-disk systems

Michael Küffmeier

C. P. Dullemond, S. Reißl, A. Krieger, T. Haugbølle, P. Caselli, J. Pineda, D. Segura-Cox

Carlsberg Reintegration fellow

SU Aurigae

synthetic image

 Krieger, Küffmeier et al. almost submitted

Ginski et al. 2021

Outline

Brief overview and new constraints on star & planet formation from observations

I

Recent and current progress in modelling

II

Future plans and ideas

III

Summary

IV

Let's go back in time to the year 2014

Wow!

Credit: ALMA (ESO/NAOJ/NRAO)

Credit:

DSHARP team

10 au

50 au

The classical picture

credit: M. Persson

star formation

planet formation

History of modeling disk formation

spherical core collapse:

rotation

magnetization (mass-to-flux ratio)

non-ideal MHD effects

dust evolution

turbulence

useful for parameter studies

\rho(r) = \frac{\rho_{\rm c} R_{\rm c}^2}{R_{\rm c}^2 + r^2}

Bonnor-Ebert sphere

or uniform density

\rho(r) = \rho_{0}

Bate, Tricco & Price (2013)

Is this the full picture?

Credit: ALMA (ESO/NAOJ/NRAO)

Ginski et al. 2021

Yen et al. 2019

Garufi et al. 2021

Pineda et al. 2020

50 au

BHB1 (Alves et al. 2020), GM Aur (Huang et al. 2021), IRS 63 (Segura-Cox in prep.), AB Aur (Grady et al. 1999 / Fukagawa et al. 2004), M512 Grant et al. 2021, Cacciapuoti+ subm.), S Cra (Gupta et al. subm.)...

Per-emb-50

Valdivia-Mena et al. 2022

Streamers:  

Late infall 

AB Aurigae

HD 100546

Credit: Grady+ 1999, Fukagawa+ 2004

Late infall can 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 hydro

R_{\rm i,d}=50\, \rm au
\Sigma(r) = 170 \left(\frac{\rm g}{\rm cm^{2}}\right) \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 2021

M_{*}=2.5\, \mathrm{M}_{\odot}

Outer disk forms around inner disk

Küffmeier+ 2021

consistent with star formation simulations by Bate '18

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

Küffmeier+ 2021

Streamers (and shadows) as signs of infall

Formation of misaligned configuration

Observable as shadows in outer disk

Küffmeier, Dullemond, Reissl & Goicovic 2021

SU Aur (Ginski et al. 2021)

300 au

Krieger, Küffmeier, ...  et al. subm.

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:

=> test infall scenario in CO channel maps

Küffmeier, Dullemond, Reissl & Goicovic 2021

Inner disk orientation

M_{\rm i, disk}=4 \ M_{\rm cloudlet}
M_{\rm cloudlet} = 1.87 \times 10^{-4} \ \mathrm{M}_{\odot}
M_{\rm i,disk} = 24 M_{\rm cloudlet}
M_{\rm i,disk}=4 \ M_{\rm cloudlet}
M_{\rm i,disk} = 0.4 \ M_{\rm cloudlet}

Küffmeier+ 2021

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 outside the disk:

significant fraction of final mass might accrete late through inflow (Küffmeier+ 2023, Pelkonen+ 2020)

Pineda et al. 2020; see also [BHB2007] 1 (Alves et al. 2020)

Küffmeier et al. 2019

binaries/fly-bys (see review by Cuello+ 2023 and references therein)

environmental effects (Cathie's talk): photoevaporation (e.g., Haworth+2020), cosmic-rays (e.g., Küffmeier+ 2020), ...

Model star formation in a Molecular Cloud

isothermal magnetohydrodynamical (MHD) with driven turbulence

adaptive mesh refinement (AMR) simulations with RAMSES

maximum resolution: ≈25 au (level of refinement: 15), root grid about ≈1600 au (level 9)

Total mass: 3000 solar masses

periodic boundary conditions

altogether 321 sink particles at last snapshot (2 Myr after the formation of the first star)

simulation setup including detailed description of sink recipe presented in Haugbølle+2018

Küffmeier, Jensen & Haugbølle '23

Origin of accreting gas

The accretion reservoir can extend beyond the core

(see also Smith+ 2011, Kuznetsova et al. 2020, Pelkonen+ 2021)

Two phase process:

Initial collapse followed by varying amount of post-collapse infall

Results:

Possibility of replenishing and refreshing the mass and chemical budget

Küffmeier, Jensen & Haugbølle '23

Late infall is common for stars*

 *unless they remain tiny

On average, stars with final masses of more than 1 solar mass accrete more than 50 % of their mass after 500 kyr

Note that some protostars still accrete after 1.2 Myr

Küffmeier, Jensen & Haugbølle '23

On average, stars with increasing final mass undergo prolonged infall

Orientation of star-disk systems can change substantially

Küffmeier, Haugbølle, Pineda & Segura-Cox

Open question:

Does late infall change the orientation of star and disk?

DISCLAIMER! The resolution is 25 au at best. Infall is caught, but disk is not resolved (yet).

\mathrm{FA} = \sqrt{ \frac{1}{2}} \frac{\sqrt{(\lambda_1 - \lambda_2)^2 + (\lambda_2 - \lambda_3)^2 + (\lambda_3 - \lambda_1)^2}}{\sqrt{\lambda_1^2 + \lambda_2^2 + \lambda_3^2}}

Fractional anisotropy based on tracer particles

Fractional anisotropy (FA) serves as a good measure for the (an-)isotropy of accretion.

FA=0: perfectly isotropic accretion, FA=1: maximally anisotropic

FA can also be a useful measure to compare (an)isotropy of stellar spins in clusters 

Late infall is more anisotropic than early collapse

\mathrm{FA} = \sqrt{ \frac{1}{2}} \frac{\sqrt{(\lambda_1 - \lambda_2)^2 + (\lambda_2 - \lambda_3)^2 + (\lambda_3 - \lambda_1)^2}}{\sqrt{\lambda_1^2 + \lambda_2^2 + \lambda_3^2}}

Fractional anisotropy (FA) serves as a good measure for the (an-)isotropy of accretion.

FA=0: perfectly isotropic accretion, FA=1: maximally anisotropic

\frac{\Delta t_{\rm single}}{\Delta t_{\rm single}+\Delta t_{\rm mult}}
1
0

FA can also be a useful measure to compare (an)isotropy of stellar spins in clusters 

Accretion as single star or as part of multiple

Possible trend that lower mass stars are more likely to be part of binary or systems of higher order during accretion

 Sequence of star, disk & planet formation

Pineda ... Küffmeier et al. 'Protostars and Planets VII'

.

 

 

 

.

Star & disk can be replenished by infall of initially unbound material

credit: Lützen & Küffmeier

DSTREAM: Disk Systems That are Replenished and Evolve through Accretion of Material

Outlook: How do late infall events ("streamers") affect the disk?

Christian Granzow Holm

  • is the disk solely replenished with fresh material while keeping its overall configuration?
  • does the infalling material have an excess in angular momentum that frequently leads to the formation of a new misaligned outer disk (and if yes, for how long)?
  • is (late) infall catastrophic in nature and destroys the disk to form a completely new one?

Take-away points

Late infall changes the orientation of star-disk systems substantially.

Post-collapse infall is common. Probability increases with increasing stellar mass.

Late infall via streamers is more anisotropic than early collapse.

On average, stars with final masses of more than 1 solar mass accrete >50 % of their mass after 500 kyr

Küffmeier, Jensen & Haugbølle '23

Heterogeneous accretion implies late infall

Observational indication: luminosity bursts

(PPVII review by Fischer et al. 2023)

Zoom-in on embedded stars

Küffmeier et al.

2019

Küffmeier et al. 2018

Küffmeier, Reißl et al. 2020

bridge structure similar to IRAS 16293--2422 (e.g. Sadavoy+ 2018, van der Wiel+ 2019, Maureira+ 2020)

~1500 AU

realistic initial conditions!