deuterium fractionation in protoplanetary disks
TRANSCRIPT
Deuterium Fractionation in Protoplanetary Disks
Richard Teague, Max Planck Institute for Astronomy D. Semenov, S. Guilloteau, Th. Henning, A. Dutrey, V. Wakelam, E. Chapillon, V. Piétu and the Chemistry in Disks Collaboration
arXiv:1501.00984
Sub-mm observations probe low energy environments.
Deuterium Fractionation
Ceccarelli et al. PPVI chapter provides a comprehensive review of deuterium fractionation.
CxH3+
Light Hydrocarbons
T > 30 K
H3+
Trihydrogen Cation
T < 30 K
HD Deuterium Reservoir
DCO+ Deuterated Molecules
See also Henning & Semenov (2013) Chem. Rev. and Dutrey et al. (2013) PPVI Chapter.
Well understood* structure helps in the interpretation of observations.
Protoplanetary Disks
*To some degree…
Keplerian rotation dominates kinematics.
Grain growth and sedimentation.
Elevated ‘molecular layer’.
Radial & vertical gradients in physical properties.
Molecular line emission probes distinct regions of the disk.
Molecular Menagerie
Bergin et al. (2013), van Dishoeck et al. (2003) Öberg et al. (2012), Cleeves et al. (2014)
Simple Diatomic Molecules e.g. HD
Carbon Bearing Species e.g. DCO+, DCN
Nitrogen Bearing Species e.g. H2D+, N2D+
No molecule traces the entire disk; must use complementary studies.
More than just thermal history probes.
DCO+ and HCO+
H2D+
HCO+
DCO+ H3+ H2
CO
HD
H2
CO
ice
ice
Ionization.
DCO+ and HCO+
H2D+
HCO+
DCO+ H3+ H2
CO
HD
H2
CO
ice
ice
Deuterium fractionation efficiency.
DCO+ and HCO+
H2D+
HCO+
DCO+ H3+ H2
CO
HD
H2
CO
ice
ice
CO depletion.
DCO+ and HCO+
H2D+
HCO+
DCO+ H3+ H2
CO
HD
H2
CO
ice
ice
Chemical modelling is essential to interpret observations.
DCO+ and HCO+
H2D+
HCO+
DCO+ H3+ H2
CO
HD
H2
CO
ice
ice
Carried out with IRAM Plateau de Bure Interferometer, Teague et al. (in press)
Zeroth Moment Maps - Total Intensity
Observations of DM Tau
Δα [”]
Δδ [”
]
Carried out with IRAM Plateau de Bure Interferometer, Teague et al. (in press)
First Moment Maps - Kinematics
Observations of DM Tau
Δα [”]
Δδ [”
]
Derives best fit column densities from observations.
DISKFIT
100
10-1
10-2
R D(H
CO+ )
40 100 600Radius (au)
N(DCO+)N(HCO+)
RD(HCO+) =
Derives best fit column densities from observations.
DISKFIT
Teague et al. (in press), Pietu et al. (2007)
100
10-1
10-2
R D(H
CO+ )
40 100 600Radius (au)
DM Tau
Typical Error
TW Hya and HD 163296
Protoplanetary Disks
100
10-1
10-2
R D(H
CO+ )
40 100 600Radius (au)
Qi et al. (2008), Mathews et al. (2014)
TW H
ya
HD 163296
Typical Error
Ensemble of prestellar cores.
Prestellar Cores
Butner et al. (1995)
100
10-1
10-2
R D(H
CO+ )
40 100 600Radius (au)
Prestellar Cores
Typical Error
Time dependent chemistry code.
ALCHEMIC
100
10-1
10-2
R D(H
CO+ )
40 100 600Radius (au)
5⠐ 106
106
104
103
105 Time (yrs)
Teague et al. (in press), Semenov et al. (2010), Albertsson et al. (2013), Albertsson et al. (2014a)
Typical Error
Molecular DistributionVertical temperature gradients result in different vertical profiles.
Teague et al. (in press)
40 100 600 40 100 6000
1
2z /
R
Radius (au)
log10(x(DCO+)) log10(x(HCO+))
100
10-1
10-2
R D(H
CO+ )
40 100 600Radius (au)
X-Ray Luminosity of the star.
Modelling
Decreasing LX
Increasing LX
Typical Error
100
10-1
10-2
R D(H
CO+ )
40 100 600Radius (au)
Larger grains, a = 1um
Modelling
Larger grains
Typical Error
What can we probe with RD(HCO+)?
Results
X-rays dominates ionization in the HCO+ molecular layer.
Ionization
Grain evolution heavily impacts the freeze out and
desorption of CO.
CO Depletion
Radial temperature gradient in disk drives radial gradient in RD.
Deuterium Fractionation
Beyond Remote SensingComparison of log10((RD (H2O))) values in the Solar System.
Adapted from Hartogh et al. (2011)
Jupiter Family Comets
Ea
rth
Ma
rs
Jup
iter
Satu
rn
Ura
nu
s
Nep
tun
e
Oo
rt Clo
ud
- 3.5
- 4.5
- 5.5
Cycle 3 - Band 7
Cycle 2
Cycle 3 - Bands 3, 4, & 6
Angular resolution assuming a source distance of 150 pc,
maximum baselines and observing frequency
270 GHz.
Deuterium FractionationHelping unraveling the planet formation process…
Protoplanetary Disks
Planets &
AtmospheresPrestellar Cores
DepletionThermal History
Ionization Fractionation