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Clump formation through colliding stellar winds in the Galactic Center Caldern et al. (2016) Diego Caldern 1 , J. Cuadra 1 , A. Ballone 2,3 , M. Schartmann 3 , A. Burkert 2,3 & S. Gillessen 2 1 Instituto de Astrofsica, Pontificia

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SLIDE 1

Clump formation through colliding stellar winds in the Galactic Center

Calderón et al. (2016)

Diego Calderón1, J. Cuadra1, A. Ballone2,3, M. Schartmann3, A. Burkert2,3 & S. Gillessen2

1Instituto de Astrofísica, Pontificia Universidad Católica de Chile 2Max-Planck-Institute for Extraterrestrial Physics, Germany 3Universitätssternwarte der Ludwig-Maximilians-Universität, Germany 4 Center for Astrophysics and Supercomputing, Swinburne University of Technology

  • “Dynamics and Accretion at the Galactic Center”

Aspen winter conference, February 9th 2016

Numerical Hydrodynamics Group IAUC

Image of η Carinae by HST

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SLIDE 2

Gas clumps in the Galactic Center

Animation from Cuadra et al. (2008) Numerical Hydrodynamics Group IAUC

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SLIDE 3

Gas clumps in the Galactic Center

Animation from Cuadra et al. (2008) Numerical Hydrodynamics Group IAUC

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SLIDE 4

Gas clumps in the Galactic Center

Animation from Cuadra et al. (2008) Numerical Hydrodynamics Group IAUC

Are they physical or numerical?

( H

  • b

b s e t a l . 2 1 3 ) 


  • Could G2 be one of them?

( S c h a r t m a n n e t a l . 2 1 2 , B u r k e r t e t a l . 2 1 2 )

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SLIDE 5

Non-linear Thin Shell Instability (NTSI)

Vishniac (1994) Figure from McLeod & Whitworth (2013) Numerical Hydrodynamics Group IAUC

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SLIDE 6

Non-linear Thin Shell Instability (NTSI)

Vishniac (1994) Figure from McLeod & Whitworth (2013) Numerical Hydrodynamics Group IAUC

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SLIDE 7

Non-linear Thin Shell Instability (NTSI)

Vishniac (1994) Figure from McLeod & Whitworth (2013) Numerical Hydrodynamics Group IAUC

Isothermal case

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SLIDE 8

From Stevens et al. (1992),

Colliding Winds

Figure from Stevens et al. (1992)

χ ≥ 1 ⇒ adiabatic wind χ < 1 ⇒ radiative wind

Numerical Hydrodynamics Group IAUC

χ = tcool tdyn ≈ 1 2 v5.4

8 d12

˙ M−7

Schematic representation of a colliding winds system

The NTSI can take place only if winds are radiative, i.e., form a thin shell.

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SLIDE 9

Model for a symmetric wind collision

Numerical Hydrodynamics Group IAUC

Describing the thermal evolution of the slab, we can estimate the unstable wavelength range, and the mass of possible clumps (assuming λ ~ clump size).

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SLIDE 10

Model for a symmetric wind collision

Numerical Hydrodynamics Group IAUC

Describing the thermal evolution of the slab, we can estimate the unstable wavelength range, and the mass of possible clumps (assuming λ ~ clump size).

Clumps can be created in a wide range of masses, some of them can even reach ~100 Earth masses.

10−1 100 101 Stellar Separation d (mpc) 200 300 400 500 600 700 800 900 Stellar Wind Velocity V (km s−1) A B C D E F

Minimum Clump Mass

10−1 100 101 Stellar Separation d (mpc) A B C D E F

Maximum Clump Mass χ = 1 χ = 0.5

−14 −12 −10 −8 −6 −4 −2 2 log (M/MEarth) ˙ M = 10−5 MSun yr−1

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SLIDE 11

Model for a symmetric wind collision

Numerical Hydrodynamics Group IAUC

Describing the thermal evolution of the slab, we can estimate the unstable wavelength range, and the mass of possible clumps (assuming λ ~ clump size).

Clumps can be created in a wide range of masses, some of them can even reach ~100 Earth masses.

10−1 100 101 Stellar Separation d (mpc) 200 300 400 500 600 700 800 900 Stellar Wind Velocity V (km s−1) A B C D E F

Minimum Clump Mass

10−1 100 101 Stellar Separation d (mpc) A B C D E F

Maximum Clump Mass χ = 1 χ = 0.5

−14 −12 −10 −8 −6 −4 −2 2 log (M/MEarth) ˙ M = 10−5 MSun yr−1

But…Can this happen in the Galactic Centre?

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SLIDE 12

Stellar properties from Martins et al. (2007)

Clump formation in the Galactic Centre

Numerical Hydrodynamics Group IAUC

y-axis shows maximum stellar separations for identical winds to be radiative, i.e., form thin shells. Separations of miliparsec (~200AU) scales are not very common.

0.00 0.05 0.10 0.15 0.20 0.25 Momentum Flux (MSun yr−1 km s−1) 10−3 10−2 10−1 100 101 102 2dcool

∗

(mpc) 16SE2 33E 13E4 9W AFNWNW 100 101 102 103 104 2dcool

∗

(AU)

Animation Pittard (2009)

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SLIDE 13

Stellar properties from Martins et al. (2007)

Clump formation in the Galactic Centre

Numerical Hydrodynamics Group IAUC

y-axis shows maximum stellar separations for identical winds to be radiative, i.e., form thin shells. Separations of miliparsec (~200AU) scales are not very common. What about binaries? 3 systems so far ~ 3 0 % e x p e c t e d (Pfuhl+2014)

0.00 0.05 0.10 0.15 0.20 0.25 Momentum Flux (MSun yr−1 km s−1) 10−3 10−2 10−1 100 101 102 2dcool

∗

(mpc) 16SE2 33E 13E4 9W AFNWNW 100 101 102 103 104 2dcool

∗

(AU)

Animation Pittard (2009)

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SLIDE 14

Stellar properties from Martins et al. (2007)

Clump formation in the Galactic Centre

Numerical Hydrodynamics Group IAUC

y-axis shows maximum stellar separations for identical winds to be radiative, i.e., form thin shells. Separations of miliparsec (~200AU) scales are not very common. What about binaries? 3 systems so far ~ 3 0 % e x p e c t e d (Pfuhl+2014)

0.00 0.05 0.10 0.15 0.20 0.25 Momentum Flux (MSun yr−1 km s−1) 10−3 10−2 10−1 100 101 102 2dcool

∗

(mpc) 16SE2 33E 13E4 9W AFNWNW 100 101 102 103 104 2dcool

∗

(AU)

  • I

R S 1 6 S W

  • >

b i n a r y s y s t e m

  • d

~ 1 µ p c , P ~ 1 9 . 5 d & w i n d s p e e d ~ 5 k m / s 


  • L
  • c

a t e d i n t h e c l

  • c

k w i s e d i s c 


  • G

2

  • r

i g i n i n t h e d i s c ( S c h a r t m a n n e t a l . 2 1 5 )

Animation Pittard (2009)

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SLIDE 15

Stellar properties from Martins et al. (2007)

Clump formation in the Galactic Centre

Numerical Hydrodynamics Group IAUC

y-axis shows maximum stellar separations for identical winds to be radiative, i.e., form thin shells. Separations of miliparsec (~200AU) scales are not very common. What about binaries? 3 systems so far ~ 3 0 % e x p e c t e d (Pfuhl+2014)

0.00 0.05 0.10 0.15 0.20 0.25 Momentum Flux (MSun yr−1 km s−1) 10−3 10−2 10−1 100 101 102 2dcool

∗

(mpc) 16SE2 33E 13E4 9W AFNWNW 100 101 102 103 104 2dcool

∗

(AU)

  • I

R S 1 6 S W

  • >

b i n a r y s y s t e m

  • d

~ 1 µ p c , P ~ 1 9 . 5 d & w i n d s p e e d ~ 5 k m / s 


  • L
  • c

a t e d i n t h e c l

  • c

k w i s e d i s c 


  • G

2

  • r

i g i n i n t h e d i s c ( S c h a r t m a n n e t a l . 2 1 5 )

Animation Pittard (2009)

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SLIDE 16

Another option: Mass-losing star encounters

Stellar encounters could be clumps sources too!

Numerical Hydrodynamics Group IAUC

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SLIDE 17

Another option: Mass-losing star encounters

Stellar encounters could be clumps sources too!

Numerical Hydrodynamics Group IAUC

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SLIDE 18

Another option: Mass-losing star encounters

We ran Newtonian test particles gravity simulation of the O/WR stars (using orbital data from Paumard et al. 2006) for 10,000 yrs and register close encounters (<2,000AU~10mpc). Stellar encounters could be clumps sources too!

Numerical Hydrodynamics Group IAUC

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SLIDE 19

Another option: Mass-losing star encounters

We ran Newtonian test particles gravity simulation of the O/WR stars (using orbital data from Paumard et al. 2006) for 10,000 yrs and register close encounters (<2,000AU~10mpc). Stellar encounters could be clumps sources too!

W e f

  • u

n d t h e s e e n c

  • u

n t e r s a r e n

  • t

v e r y c

  • m

m

  • n

, a b

  • u

t 1 i n 1 , y r .

Numerical Hydrodynamics Group IAUC

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SLIDE 20

Conclusions

  • We developed a straight-forward diagnostic for clump formation

through NTSI with (Mdot, Vwind, d) as input.

  • For stellar separations <2,000AU, clumps can be created in a

very wide range of masses reaching 100 Earth masses.

  • Symmetric colliding wind encounters are an unlikely source of

clumps in the Galactic Centre.

  • Close encounters (<2,000AU) of the known O/WR are not

very common events, however some of them might be clump sources.

  • IRS 16SW is the most promising clump source and deserves

future study (currently working on it).

Numerical Hydrodynamics Group IAUC

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SLIDE 21

Work in progress

Calculate a clump mass function for different systems, rate of ejecta to the ISM and the impact of orbital motion. Currently, we are running and analysing hydro AMR simulations.

Numerical Hydrodynamics Group IAUC

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SLIDE 22

Work in progress

Calculate a clump mass function for different systems, rate of ejecta to the ISM and the impact of orbital motion. Currently, we are running and analysing hydro AMR simulations.

Numerical Hydrodynamics Group IAUC

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SLIDE 23

Work in progress

Calculate a clump mass function for different systems, rate of ejecta to the ISM and the impact of orbital motion. Currently, we are running and analysing hydro AMR simulations.

Numerical Hydrodynamics Group IAUC

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SLIDE 24

Thanks for your attention!

Numerical Hydrodynamics Group IAUC Numerical Hydrodynamics Group IAUC