Post on 15-Aug-2021
Thanks to:James Owen, C. Clarke (IoA); A. Glassgold (Berkeley);
S. Mohanty (Imperial); N. Turner (JPL); J. Drake, J. Raymond (CfA)
X-ray irradiated protoplanetary discs
Barbara Ercolano University of Exeter
Tuesday, 27 July 2010
Tuesday, 27 July 2010
Tuesday, 27 July 2010
X-ray Feedback on Low Mass Star & Planet Formation
Taurus – Spitzer Space Telescope
Tuesday, 27 July 2010
X-ray Feedback on Low Mass Star & Planet Formation
Taurus – Spitzer Space Telescope
Gued
el e
t al.,
200
7
Tuesday, 27 July 2010
What drives the dispersal of disks? On what timescales?
What environments are favourable to the formation of terrestrial and giant planets?
What is the effect of irradiation on planetary atmospheres?
X-ray Feedback on Low Mass Star & Planet Formation
Taurus – Spitzer Space Telescope
Tuesday, 27 July 2010
Tuesday, 27 July 2010
Credit: NASA/LMSAL
Tuesday, 27 July 2010
X-Rays
Tuesday, 27 July 2010
X-RaysMRI
Tuesday, 27 July 2010
X-Rays
Dead Zone
Proto-Earth
MRI
Tuesday, 27 July 2010
X-Rays
Dead Zone
Proto-Earth
Proto-Jupiter
Photoevaporation
migration
MRI
Tuesday, 27 July 2010
•‘Hard’ X-rays: MRI and Dead Zones
•‘Soft’ X-rays: Disc photoevaporation
Overview
Tuesday, 27 July 2010
•‘Hard’ X-rays: MRI and Dead Zones
•‘Soft’ X-rays: Disc photoevaporation
Overview
‘Hard’ : E > 1 keV
‘Soft’ : 0.1 < E < 1 keV
Tuesday, 27 July 2010
•‘Hard’ X-rays: MRI and Dead Zones
•‘Soft’ X-rays: Disc photoevaporation
Overview
‘Hard’ : E > 1 keV
‘Soft’ : 0.1 < E < 1 keV
Tuesday, 27 July 2010
•MRI and Dead Zones
•Igea & Glassgold 1999
•X-rays from YSO dominate the disc ionisation structure
•Discs around solar-type stars mostly MRI active
•Dead-zone should extend to aprrox 5 AU
Tuesday, 27 July 2010
•Igea & Glassgold 1999
Tuesday, 27 July 2010
•Turner & Sano 2008•Turner & Drake 2009
•Dead or Undead?
•Use IG99 ionisation rates for stellar X-ray & consider other ionisation processes in the MMSN
•Dead zones basically always present
•Undead zones important?
•MRI active
•dead•undead
Tuesday, 27 July 2010
•Mohanty, Ercolano & Turner 2010 in prep
•MRI & (Un)Dead Zones in YSO Discs
•New ionsation rates calcs with MOCASSIN
•Chemical network to account for recombinations on grains
•Parameter space investigation
Tuesday, 27 July 2010
•Mohanty, Ercolano & Turner 2010 in prep
•MRI & (Un)Dead Zones in YSO Discs
•New ionsation rates calcs with MOCASSIN
•Chemical network to account for recombinations on grains
•Parameter space investigation
•DZ present in all discs with Md > 1% M*
•MRI is reduced for discs with small grains or low densities
•Grains play a major role in determining accretion in discs
Tuesday, 27 July 2010
•‘Hard’ X-rays: MRI and Dead Zones
•‘Soft’ X-rays: Disc photoevaporation
Overview
‘Hard’ : E > 1 keV
‘Soft’ : 0.1 < E < 1 keV
Tuesday, 27 July 2010
high mass
Viscous evolution predicts….
high accretion rate
time
low mass
low accretion rate
Tuesday, 27 July 2010
high mass
Viscous evolution predicts….
Observations instead show….
t~106yrs t~107yrs
high accretion rate
time
low mass
low accretion rate
Tuesday, 27 July 2010
high mass
Viscous evolution predicts….
Observations instead show….
t~106yrs t~107yrsRare transition disk
high accretion rate
time
low mass
low accretion rate
Tuesday, 27 July 2010
Alexander, based on a description of viscous evolution
Viscous evolution
Ac
cr
etio
n r
ate
The Classical EUV switch modelClarke et al. (2001); Matsuyama et al. (2003);
Ruden (2004)
Time
Tuesday, 27 July 2010
Alexander, based on a description of viscous evolution
Viscous evolution
Wind rate
Ac
cr
etio
n r
ate
The Classical EUV switch modelClarke et al. (2001); Matsuyama et al. (2003);
Ruden (2004)
Time
Tuesday, 27 July 2010
Alexander, based on a description of viscous evolution
Viscous evolution
Wind rate
Viscous +windAc
cr
etio
n r
ate
The Classical EUV switch modelClarke et al. (2001); Matsuyama et al. (2003);
Ruden (2004)
Time
Tuesday, 27 July 2010
Modelling photoevaporating disks: HOW?
Ercolano+ 2008, 2009, Owen+ 2010, Ercolano & Clarke 2010, Ercolano & Owen 2010, Owen, Ercolano & Clarke 2010
Tuesday, 27 July 2010
Modelling photoevaporating disks: HOW?
1) Radiative Transfer (MOCASSIN) a) 2D (at least) b) gas (photoionisation) + dust 2) Hydrodynamics (ZEUS)
3) Viscous Evolution
Ercolano+ 2008, 2009, Owen+ 2010, Ercolano & Clarke 2010, Ercolano & Owen 2010, Owen, Ercolano & Clarke 2010
Tuesday, 27 July 2010
Owen, Ercolano, Clarke & Alexander, 2010
Tuesday, 27 July 2010
Owen, Ercolano, Clarke & Alexander, 2010
Total photoevaporation rate of ~1.4e-8 Msun/yr
(for Lx = 2e30erg/sec)
Comparable to accretion rates of CTTs
Tuesday, 27 July 2010
Owen, Ercolano, Clarke & Alexander, 2010Tuesday, 27 July 2010
Tuesday, 27 July 2010
Ow
en, E
rcol
ano
& C
lark
e 20
10, i
n pr
ep
0
2
4
log(Surface Density) [g cm 3]
log(
Surfa
ce D
ensi
ty) [
g cm
3 ]
0.1 1 10 10010 11
10 10
10 9
10 8
Radius [AU]
Accr
etio
n R
ate
[M
yr1 ]
!
No photoevaporation
Photoevaporation
Tuesday, 27 July 2010
Ow
en, E
rcol
ano
& C
lark
e 20
10, i
n pr
ep
0
2
4
log(Surface Density) [g cm 3]
log(
Surfa
ce D
ensi
ty) [
g cm
3 ]
0.1 1 10 10010 11
10 10
10 9
10 8
Radius [AU]
Accr
etio
n R
ate
[M
yr1 ]
!
No photoevaporation
Photoevaporation
Photoevaporation-starved accretion?
Tuesday, 27 July 2010
Why do non-accreting YSOs (WTTs) have higher LX than accreting YSOs (CTTs) ??
Tuesday, 27 July 2010
Accretion ‘disturbs’ X-ray emission
(e.g. Flaccomio et al 2003, Stassun et al 2004, Preibisch et al 2005, Jardine et al 2006, Guedel et sl 2007, Gregory et al 2007)
Why do non-accreting YSOs (WTTs) have higher LX than accreting YSOs (CTTs) ??
Tuesday, 27 July 2010
Accretion ‘disturbs’ X-ray emission
(e.g. Flaccomio et al 2003, Stassun et al 2004, Preibisch et al 2005, Jardine et al 2006, Guedel et sl 2007, Gregory et al 2007)
Why do non-accreting YSOs (WTTs) have higher LX than accreting YSOs (CTTs) ??
X-rays modulate accretion?X-ray photoevaporation-starved accretion
(Drake et al 2009)
Tuesday, 27 July 2010
Drake et al 2009
Tuesday, 27 July 2010
Ow
en, E
rcol
ano
& C
lark
e 20
10, i
n pr
ep
0 2 4 6 8 10 121028
1029
1030
1031
Time [Myr]
Xra
y Lu
min
osity
[erg
s1 ]
WTTs (discless)
CTTs (discbearing)
Data points from Taurus (Guedel et al 2007)
Tuesday, 27 July 2010
Ow
en, E
rcol
ano
& C
lark
e 20
10, i
n pr
ep
10.5 10 9.5 9 8.5 8 7.5 7
log(Accretion Rate) [M yr 1]
29
29.5
30
30.5
31
11 10.5 10 9.5 9 8.5 8 7.528.5
29
29.5
30
30.5
log(
Xra
y Lu
min
osity
) [er
g s
1 ]
!Log(Accretion Rate) [Msun/yr]
Log(
X-r
ay L
umin
osity
) [e
rg/s
ec]
0.5-3.5 Myr 1.5-4.5 Myr
4-8 Myr integrated lifetime
Tuesday, 27 July 2010
Conclusions
X-rays control the evolution & dispersal of protoplanetary discs
& affect planet formation through:
Tuesday, 27 July 2010
•Ionising the discs thus allowing MRI to work•(‘hard’ x-ray)
•Driving a photoevaporative wind that erodes the disc from the inside-out•(‘soft’ X-ray)
•(Possibly) modulating accretion through photoevaporation-starved accretion•(‘soft’ X-ray)
Conclusions
X-rays control the evolution & dispersal of protoplanetary discs
& affect planet formation through:
Tuesday, 27 July 2010
Thank You!
Tuesday, 27 July 2010