How old are you? 

Michael Küffmeier (Marie Skłodowska-Curie global fellow)

Rejuvenation of disks by (late) infall

Sigurd Jensen, Jaime Pineda, Teresa Valdivia (all MPE), Troels Haugbølle (NBI)

Let's go back in time to the year 2014

Wow!

Credit: ALMA (ESO/NAOJ/NRAO)

Credit:

DSHARP team

10 au

50 au

Credit: NASA/ESA Hubble space telescope &

ALMA (ESO/NAOJ/NRAO)

The big challenge:

link planet to star formation

50 au

The classical picture

Greene 2001

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}

Disk size distribution

Tobin+ 2019

Are disks already born small in some regions?

 What is the effect of local ionization rates?

 Cosmic-ray ionization rate (or even Al-26)?

Is this the full picture?

Streamers!

What about magnetic fields?

Help! Where is the disk?!

Ohmic, Ambipolar, Hall 

Turbulence

Santos-Lima et al. 2012

Hydro

ideal MHD

non-ideal MHD

turbulence + MHD

Other effect: dust

dust growth weakens magnetic braking => larger disks

Zhao et al. 2018, Marchand et al. 2020

dust-rich disks from collapse

"ash-fall" scenario

Tsukamoto et al. 2021

 Lebreuilly et al. 2020

dust accumulates

Credit: ALMA (ESO/NAOJ/NRAO)

Ginski et al. 2021

Yen et al. 2019

Garufi et al. 2021

Pineda et al. 2020

50 au

see also:

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), ...

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, Calcutt & Kristensen 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

Formation of embedded protostellar multiple

Küffmeier, Reißl et al. 2020

Magnetic field in bridge

Synthetic observation with POLARIS

Field strength in bridge: 

about 1 to 2 mG

Polarization fraction in bridge:

a few %

Synthetic dust polarization maps at 1.3 mm

Küffmeier, Reißl et al. 2020

Emitted radiation

Polarization fraction in bridge:

a few %

Polarization fraction in bridge:

up to 20 %

IRAS 16293--2422

Sadavoy et al. 2018

=> IRAS 16293-2422 is strongly magnetized

Wavelength dependence: 1.3 mm vs 53 micron

Emitted radiation

1.3 mm: good tracer of magnetic field

53 micron: poor tracer of magnetic field

Küffmeier, Reißl et al. 2020

Two reasons for wavelength dependence

Küffmeier, Reißl et al. 2020

Self-scattering

Dichroic extinction

Take-away for scales beyond >100 au

< 200 micron: dichroic extinction and self-scattering; no trace of B

> 200 micron: thermal emission; linear polarization traces B

The connection to the larger scales

Küffmeier, Haugbølle & Nordlund 2017

Accretion is heterogeneous

Küffmeier, Haugbølle & Nordlund 2017

Observational indication: luminosity bursts

The connection to the larger scales

Küffmeier et al. 2017 / 2022 in prep.

Gas from beyond the prestellar core can fall onto the star-disk system

Late infall happens more often than assumed

For solar mass stars ~50 % of final mass from beyond prestellar core! (Pelkonen et al. 2021)

Can disks be rejuvenated?

Küffmeier et al. 2022 in prep

Possibility of replenishing and refreshing the mass and chemical budget

Streamers (and shadows?) as signs of infall

Formation of misaligned configuration

Observable as shadows in outer disk

Ginski et al. 2021

Küffmeier, Dullemond et al. 2021

see also Bate 2018

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 et al. 2021

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

Outer disk forms around inner disk

Küffmeier et al. 2021

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 et al. 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 et al. 2021

Revised picture

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

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Segura-Cox et al. in prep.

Star and planet formation are two sides of the same medal

The disk is not a static entity, but rather a buffer zone

*we haven't even touched (proto-)stellar multiplicity

Revised picture

Session start

My talk

Coffee break!