J/A+A/592/A83 HD 100546 and TW Hya model abundances (Kama+, 2016)
Volatile-carbon locking and release in protoplanetary disks.
A study of TW Hya and HD 100546.
Kama M., Bruderer S., Dishoeck E.F.van , Hogerheijde M., Folsom C.P.,
Miotello A., Fedele D., Belloche A., Gusten R., Wyrowski F.
<Astron. Astrophys. 592, A83 (2016)>
=2016A&A...592A..83K 2016A&A...592A..83K (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Models ; Abundances
Keywords: astrochemistry - protoplanetary disks
Abstract:
The composition of planetary solids and gases is largely rooted in the
processing of volatile elements in protoplanetary disks. To shed light
on the key processes, we carry out a comparative analysis of the
gas-phase carbon abundance in two systems with a similar age and disk
mass, but different central stars: HD 100546 and TW Hya.
We combine our recent detections of C0 in these disks with
observations of other carbon reservoirs (CO, C+, C2H) and gas-mass
and warm-gas tracers (HD, O0), as well as spatially resolved ALMA
observations and the spectral energy distribution. The disks are
modelled with the DALI 2D physical-chemical code. Stellar abundances
for HD 100546 are derived from archival spectra.
Upper limits on HD emission from HD 100546 place an upper limit on the
total disk mass of ≤0.1M☉. The gas-phase carbon abundance in
the atmosphere of this warm Herbig disk is, at most, moderately
depleted compared to the interstellar medium, with Bootis star, with
solar abundances of C and O but a strong depletion of rockforming
elements. In the gas of the T Tauri disk TW Hya, both C and O are
strongly underabundant, with [C]/[H]gas=(0.2-5.0)x10-6 and C/O>1.
We discuss evidence that the gas-phase C and O abundances are high in
the warm inner regions of both disks. Our analytical model, including
vertical mixing and a grain size distribution, reproduces the observed
[C]/[H]gas in the outer disk of TW Hya and allows to make
predictions for other systems.
Description:
Best-fit models for TW Hya and HD 100546 as presented in the paper.
For TW Hya, the model has C/H=1e-6 and C/O=1.5. For HD 100546, two
roughly equivalent solutions are given: with gas/dust=100 (C/H=1e-5)
and gas/dust=10 (C/H=1e-4), both with a Solar O/H ratio.
The DALI code is described in detail in Bruderer et al.
(2012A&A...541A..91B 2012A&A...541A..91B) and Bruderer (2013A&A...559A..26R 2013A&A...559A..26R). The
specifics of its implementation in the disk fitting are described in
the paper which this dataset accompanies.
The columns in the provided model files are:
r_mid(au) - the radial central point of the grid cell (star=0)
z_mid(au) - the vertical central point of the grid cell (midplane=0)
n_gas(cm-3) - total number density of gas in the cell
t_gas(K) - gas temperature
t_dust(K) - dust temperature
G0unatt - unattenuated local UV field in Draine units
(2.7e-3erg/s/cm2 between 911Å and 2067Å)
G_0 - local UV field in Draine units
(2.7e-3erg/s/cm2 between 911Å and 2067Å)
A_V - effective A_V in magnitudes (AUV=-log10(G0/G0unatt), AV=AUV/3)
H - number density of atomic hydrogen
H2 - number density of molecular hydrogen
e- - number density of free electrons
C - number density of atomic carbon
CO - number density of carbon monoxide
O - number density of atomic oxygen
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
11 33 25.44 -70 11 41.2 HD 100546 = HIP 56379
11 01 51.91 -34 42 17.0 TW Hya = V* TW Hya
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
hd_gd10.dat 140 17381 HD 100546 model, solution with low gas-to-dust
ratio (10) and solar carbon (C/H=1e-4)
hd_gd100.dat 140 13561 HD 100546 model, solution with standard
gas-to-dust (100) and somewhat depleted
carbon (C/H=1e-5)
twco15.dat 140 12221 TW Hya model, C/H=1e-6, O/H=6.67e-7
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Byte-by-byte Description of file: hd*.dat tw*.dat
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Bytes Format Units Label Explanations
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1- 9 E9.4 AU rmid Radial central point of the grid cell
(star=0) (r_mid(au))
11- 19 E9.4 AU zmid Vertical central point of the grid cell
(midplane=0) (z_mid(au))
21- 29 E9.4 cm-2 ngas Total number density of gas in the cell
(n_gas(cm-3))
31- 39 E9.4 K tgas Gas temperature(t_gas(K))
41- 49 E9.4 K tdust Dust temperature(t_dust(K))
51- 59 E9.4 --- G0unatt Unattenuated local UV field in Draine units
(2.7e-3erg/s/cm2 between 911Å and 2067Å)
(G0unatt)
61- 69 E9.4 --- G0 Local UV field in Draine units
(2.7e-3erg/s/cm2 between 911Å and 2067Å)
(G_0)
71- 80 E10.4 mag AV Effective AV (AUV=-log10(G0/G0unatt),
AV=AUV/3) (A_V)
82- 90 E9.4 --- H Number density of atomic hydrogen (H)
92-100 E9.4 --- H2 Number density of molecular hydrogen (H2)
102-110 E9.4 --- e- Number density of free electrons (e-)
112-120 E9.4 --- C Number density of atomic carbon (C)
122-130 E9.4 --- CO Number density of carbon monoxide (CO)
132-140 E9.4 --- O Number density of atomic oxygen (O)
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Acknowledgements:
Mihkel Kama, mihkelkama(at)gmail.com
(End) Patricia Vannier [CDS] 27-Jun-2016