1. art and entertainment
2. movies and tv
3. movies

Observational Properties
of Protoplanetary Disks
Leonardo Testi - ESO/Arcetri
[email protected]; [email protected]
Observational Properties
of Protoplanetary Disks
Leonardo Testi - ESO/Arcetri
[email protected]; [email protected]
•
Today:
•
•
•
Young stars: ages and related uncertainties
Young stars: coronae and activity
Disk-star interaction: accretion and its variability
Questions from today
•
•
•
•
Give me more on CAI/chondrules!
•
will come back to this, but not on dating process (Connelly+2012)
This D/H story, is it relevant?
•
Will come back to this, have a look at Mumma & Charnley (2011)
Where is ALMA?
•
Safe and sound on Chajnantor (…coming, no worries…)
Aren’t you supposed to talk about disks?
•
Trust me, they will be coming…
Present limits
Species not present before processing
wavelength ( m)
8% w.r.t. CO
0.3%
0.3%
0.2%
4.2
0.2
4.4
4.6
12
12
CO2
4.8
C 3O
0.1
CO at 16 K
C7O2
CO2
C5O2
C2O
C4O
0.0
2400
2300
2200
2100
2000
-1
wavenumber (cm )
Palumbo et al. 2008
26/03/2014
+
CO
C5O2
C3O2
Solid CO
5.2
+200 keV H
13
C7O2
13
5
as deposited
CO
C3O2
optical depth
CO2
C3O2
C2O
C3O
Maria Elisabetta Palumbo – WP 6 – iALMA kick-off
23
1900
2
8
Core
Disk
Debris Disk
L
(Beckwith and Sargent 1996)
From Cores to Planetary Systems
Part III
Stars, coronae,
accretion
Disk-star system
Radio&cm&
Wind##
Protoplanetary#Disk#
Ac/ve#star#
X-rays
Radio&m)dm&
Accretion flow
Oprical-UV
15#GHz#
Testi et al. 2014/15
1#GHz#SKA1#
Young star
Palla & Stahler 1999
Pre-MS evolution
• Protostellar phase:
dM/dt~10-5Mʘ/yr
•
tKH~GM2/RL:
•
• 10 M
0.5 Mʘ; tKH~108 yr
ʘ; tKH~10
•
•
5
yr
Stars more massive than
~8Mʘ do not show a premain sequence phase
Initial conditions are
uncertain
Palla & Stahler 1999
Young stars ages
Reggiani+2011
Young stars ages
Baraffe+2002
• Comparison of pre-MS tracks from different groups
• Different treatment of the internal physics, boundary
(atmospheres) and initial (formation) conditions
Young stars ages
Baraffe+2015
• Comparison of pre-MS tracks from different groups
• Different treatment of the internal physics, boundary
(atmospheres) and initial (formation) conditions
Young stars ages
Reggiani+2011
• At young ages PMS tracks cannot be
trusted to the level we would like
•
Different physics in the models yield
to ~Myr differences in ages
Young stars ages
Bell+2013
• Comparison of pre-MS tracks ages with MS-fitting techniques
• Up to a factor of 2 difference in ages
• Use multiple techniques and cross-check when possible
Disk-star system
Radio&cm&
Wind##
Protoplanetary#Disk#
Ac/ve#star#
X-rays
Radio&m)dm&
Accretion flow
Oprical-UV
15#GHz#
Testi et al. 2014/15
1#GHz#SKA1#
Stellar coronae
• In optical infrared we
probe the
photospheres
T~3000-10000K mostly
Stellar coronae
• In optical infrared we
probe the
photospheres
T~3000-10000K mostly
• X-ray observations
reveal very active
coronae in young stars
• Highly variable: flares
and flickering
Stellar coronae
• In optical infrared we
probe the
photospheres
T~3000-10000K mostly
• X-ray observations
reveal very active
coronae in young stars
• Highly variable: flares
and flickering
Pillitteri+2010
Stellar coronae
• In optical infrared we
probe the
photospheres
T~3000-10000K mostly
• X-ray observations
reveal very active
coronae in young stars
• Highly variable: flares
and flickering
Preibisch & Zinnecker 2002
Stellar coronae
Th. Preibisch
• Coronal activity fades with time
• Luminosities are ~3 orders of magnitude higher at early ages
• Important implications on disk evolution (and young planets)
5 min pause
• At least he started talking about disks, but why on
Earth is all this relevant to “PP” disks?
• Is there a relationship between all this and what we
discussed earlier today?
• Creative thinking
==>
Disk-star system
Radio&cm&
Wind##
Protoplanetary#Disk#
Ac/ve#star#
X-rays
Radio&m)dm&
Accretion flow
Oprical-UV
15#GHz#
Testi et al. 2014/15
1#GHz#SKA1#
Accretion
Manara+2014
(UV excess)
L. Hartmann
• Direct measurement of accretion:
energy released in the collision
• Indirect measurement: emission
lines from accretion columns
Gullbring+2000
Accretion
Rigliaco 2011
(UV excess)
L. Hartmann
•L
measured directly from
the UV excess luminosity
(with a correction factor
for FUV/EUV
acc
Gullbring 1998
Rm ~ 5 Rstar
Accretion
(UV excess)
L. Hartmann
• Accretion rates fall “more or less”
where predicted
• Evolution still hard to constrain
(need better age/acc measurements)
Manara 2014
Accretion variability
factor ~2-3
Costigan+ 2014
• Short term linked to rotational periods; small amplitudes
• Long timescale variability hard to constrain, maybe very strong
Early accretion
Hartmann & Kenyon 1996
Rigliaco+2015
• Accretion highly variable in the early phases of disk evolution
• Hard to measure directly: hope from infrared lines
Young stars ages
Baraffe+2010/2012
• Uncertainty from stellar accretion history
• Do we know “relative” ages?
• Early accretion history very uncertain, but potentially critical
Take home messages
• Young stars evolve relatively quickly
• To study disks and planet formation we need to look at
young stellar populations still in molecular clouds
• Ages are derived comparing observational properties with
evolutionary tracks
• There is significant uncertainty in this process
• Young stars are active: hard radiation will have an impact on
the disk and its material
• Accretion is a probe of the inner disk and has a feedback on
the disk and on the star