J/A+A/705/A49 12CO gas structures of protoplanetary disks (Zallio+, 2026)
The 12CO gas structures of protoplanetary disks in the Upper Scorpius region.
Zallio L., Rosotti G.P., Vioque M., Miotello A., Andrews S.M., Manara C.F.,
Carpenter J.M., Empey A., Kurtovic N.T., Law C.J., Longarini C.,
Paneque-carreno T., Teague R., Villenave M., Yen H.-W., Zagaria F.
<Astron. Astrophys. 705, A49 (2026)>
=2026A&A...705A..49Z 2026A&A...705A..49Z (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Carbon monoxide ; Morphology ; Stars, masses
Keywords: protoplanetary disks - circumstellar matter
Abstract:
We present measurements of key protoplanetary disk properties inferred
from parametric models of ALMA 12CO spectral line visibilities. We
derived gas-disk radii, integrated fluxes, optically thick emission
layers, and brightness temperature profiles for the disk population of
the old (4-14Myr) Upper Scorpius star-forming region. We measured CO
emission sizes for 37 disks with bright CO J=3-2 emission (S/N>10 on
the integrated flux; out of the 83 disks with CO detections), finding
that the median radius containing 90% of the flux is ∼82au, with radii
spanning from 22 up to 247au. We report a correlation between the
12CO brightness temperatures and stellar luminosities, with a
Pearson coefficient of 0.6, which we used to prove that the 12CO
optically thick emission layer primarily emanates from a region below
the superheated dust, which is optically thin to the stellar
irradiation. Moreover, we derive 33 CO emission-surface height
profiles, finding a median aspect ratio of <z/r≳0.16 in a range from
∼0.01 up to ∼0.45 over the sample. Finally, we comment on the multiple
systems in our sample, of which only some were already known. These
results confirm that it is possible to derive bulk disk properties by
modeling moderate-angular-resolution ALMA visibilities.
Description:
In this work, we fit the visibilities of the uniformly surveyed Upper
Scorpius SFR following the sample of Carpenter et al.
(2025ApJ...978..117C 2025ApJ...978..117C) and using two new parametric prescriptions to
extract the disk bulk properties. For this scope, we used the software
csalt (Andrews et al., in prep.) to model visibility spectra using two
new parametric prescriptions.
(i) We fit a total of 37 protoplanetary disks out of a sample of 83
12CO J=3-2 detection, and we report that visibility fitting becomes
difficult if the S/N of the integrated flux is ≲10;
(ii) We report the correlation between the 12CO brightness
temperature at a given radius and the 12CO R90%. We used this
correlation to understand that the 12CO optically thick layer is
more deeply embedded in the protoplanetary disk structure than the
superheated-dust optically thin-to-stellar-irradiation layer;
(iii) We extracted the 12CO J=3-2-emitting layers and <z/r> values
for "common" protoplanetary disks, deriving a median <z/r≳0.16
for our sample, which is smaller than what was reported for larger and
brighter disks (Galloway-Sprietsma et al., 2025ApJ...984L..10G 2025ApJ...984L..10G).
Moreover, we find that the correlation between <z/r> and R90% found by
Law et al. (2021ApJS..257....4L 2021ApJS..257....4L) for extended and bright disks still
holds for the compact ones.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 81 37 Fluxes from data and best-fit models, together
with foreground absorption-velocity ranges
and a keyword for residuals
table5a.dat 75 33 Values of <z/r> derived in this work
table5b.dat 39 19 Values of <z/r> from literature, Law et al.,
2022ApJ...932..114L 2022ApJ...932..114L, 2023ApJ...948...60L 2023ApJ...948...60L,
2024ApJ...964..190L 2024ApJ...964..190L
table5c.dat 46 13 Values of <z/r> from Galloway-Sprietsma et al.,
2025ApJ...984L..10G 2025ApJ...984L..10G
tablea1.dat 743 33 Fit results using the A parametrization prescription
tablea2.dat 508 4 Fit results using the B parametrization prescription
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Source Source designation (2MASS ID) (Source)
19- 30 E12.6 Jy.m/s Flux Observed 12CO flux (Flux)
32- 43 E12.6 Jy.m/s e_Flux Uncertainty in observed 12CO flux (Flux_err)
45- 56 E12.6 Jy.m/s FluxModel Modeled 12CO flux from best-fit model
(Flux_model)
58- 69 E12.6 Jy.m/s e_FluxModel Uncertainty in modeled flux (Fluxmodelerr)
71- 79 A9 m/s Absorption Measured absorption velocity (Absorption)
81 A1 --- Residuals [Y/N] Residual flag (Residuals)
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Byte-by-byte Description of file: table5a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Source Source designation (2MASS ID) (Source)
19- 30 E12.6 pc Dist Stellar distance (Dist)
32- 43 E12.6 --- z/r Aspect ratio (z/r) from CO line (z_r)
45- 56 E12.6 --- e_z/r 16th percentile of z/r (zr16)
58- 69 E12.6 --- E_z/r 84th percentile of z/r (zr84)
71- 75 A5 --- Line CO line used for measurement (Line)
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Byte-by-byte Description of file: table5b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Source Source designation (Source)
11- 17 E7.2 --- z/r Aspect ratio from CO line (z_r)
19- 25 E7.2 --- e_z/r 16th percentile of z/r (zr16)
27- 33 E7.2 --- E_z/r 84th percentile of z/r (zr84)
35- 39 A5 --- Line CO line used for measurement (Line)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5c.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Source Source designation (Source)
16- 27 E12.6 --- z/r Aspect ratio (z/r) from CO line (z_r)
29- 40 E12.6 --- e_z/r 1σ uncertainty on z/r (zrerr)
42- 46 A5 --- Line CO line used for measurement (Line)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Source Source designation (2MASS ID) (Source)
25- 36 E12.7 pc Dist Stellar distance (dist)
38- 49 E12.7 au R90med Median radius enclosing 90% of CO flux
(R90_median)
51- 62 E12.7 au e_R90med Lower 16th percentile uncertainty on R90
(R90err16th)
64- 75 E12.7 au E_R90med Upper 84th percentile uncertainty on R90
(R90err84th)
77- 88 E12.7 au R68med Median radius enclosing 68% of CO flux
(R68_median)
90-101 E12.7 au e_R68med Lower 16th percentile uncertainty on R68
(R68err16th)
103-114 E12.7 au E_R68med Upper 84th percentile uncertainty on R68
(R68err84th)
116-127 E12.7 deg inc Disk inclination (inc)
129-140 E12.7 deg e_inc Lower 16th percentile uncertainty on inc
(incerr16th)
142-153 E12.7 deg E_inc Upper 84th percentile uncertainty on inc
(incerr84th)
155-167 E13.7 deg PA [] Disk position angle (PA)
169-180 E12.7 deg e_PA Lower 16th percentile uncertainty on PA
(PAerr16th)
182-193 E12.7 deg E_PA Upper 84th percentile uncertainty on PA
(PAerr84th)
195-206 E12.7 Msun Mstar Stellar mass (M_star)
208-219 E12.7 Msun e_Mstar Lower 16th percentile uncertainty on M_star
(Mstarerr_16th)
221-232 E12.7 Msun E_Mstar Upper 84th percentile uncertainty on M_star
(Mstarerr_84th)
234-245 E12.7 au rlmed Median radius of characteristic disk scale
(rlmedian)
247-258 E12.7 au e_rlmed Lower 16th percentile uncertainty on r_l
(rlerr_16th)
260-271 E12.7 au E_rlmed Upper 84th percentile uncertainty on r_l
(rlerr_84th)
273-284 E12.7 arcsec z1med Median vertical height z1 (z1median)
286-297 E12.7 arcsec e_z1med Lower 16th percentile uncertainty on z1
(z1err_16th)
299-310 E12.7 arcsec E_z1med Upper 84th percentile uncertainty on z1
(z1err_84th)
312-323 E12.7 --- zqmed Median z_q parameter (zqmedian)
325-336 E12.7 --- e_zqmed Lower 16th percentile uncertainty on z_q
(zqerr_16th)
338-349 E12.7 --- E_zqmed Upper 84th percentile uncertainty on z_q
(zqerr_84th)
351-362 E12.7 K T10med Median brightness temperature at 10 au
(T10median)
364-375 E12.7 K e_T10med Lower 16th percentile uncertainty on T_10
(T10err_16th)
377-388 E12.7 K E_T10med Upper 84th percentile uncertainty on T_10
(T10err_84th)
390-402 E13.7 K Tqmed Median T_q (Tqmedian)
404-415 E12.7 K e_Tqmed Lower 16th percentile uncertainty on T_q
(Tqerr_16th)
417-428 E12.7 K E_Tqmed Upper 84th percentile uncertainty on T_q
(Tqerr_84th)
430-441 E12.7 au tautapmed Median tau_tap parameter (tautapmedian)
443-454 E12.7 au e_tautapmed Lower 16th percentile uncertainty on tau_tap
(tautaperr_16th)
456-467 E12.7 au E_tautapmed Upper 84th percentile uncertainty on tau_tap
(tautaperr_84th)
469-480 E12.7 au tauexpmed Median exponential tau parameter
(tauexpmedian)
482-493 E12.7 au e_tauexpmed Lower 16th percentile uncertainty on tau_exp
(tauexperr_16th)
495-506 E12.7 au E_tauexpmed Upper 84th percentile uncertainty on tau_exp
(tauexperr_84th)
508-519 E12.7 --- tau10med tau parameter at 10 au (tau10median)
521-532 E12.7 --- e_tau10med Lower 16th percentile uncertainty
(tau10err_16th)
534-545 E12.7 --- E_tau10med Upper 84th percentile uncertainty
(tau10err_84th)
547-559 E13.7 --- tauqmed Median tau_q parameter (tauqmedian)
561-572 E12.7 --- e_tauqmed Lower 16th percentile uncertainty
(tauqerr_16th)
574-585 E12.7 --- E_tauqmed Upper 84th percentile uncertainty
(tauqerr_84th)
587-598 E12.7 --- zexpmed Median z_exp (zexpmedian)
600-611 E12.7 --- e_zexpmed Lower 16th percentile uncertainty on z_exp
(zexperr_16th)
613-624 E12.7 --- E_zexpmed Upper 84th percentile uncertainty on z_exp
(zexperr_84th)
626-637 E12.7 m/s vsys Systemic velocity (vsys)
639-650 E12.7 m/s e_vsys Lower 16th percentile uncertainty on vsys
(vsyserr16th)
652-663 E12.7 m/s E_vsys Upper 84th percentile uncertainty on vsys
(vsyserr84th)
665-677 E13.7 arcsec dRA RA offset from phase center (dRA)
679-690 E12.7 arcsec e_dRA Lower 16th percentile uncertainty on dRA
(dRAerr16th)
692-703 E12.7 arcsec E_dRA Upper 84th percentile uncertainty on dRA
(dRAerr84th)
705-717 E13.7 arcsec dDE DEC offset from phase center (dDEC)
719-730 E12.7 arcsec e_dDE Lower 16th percentile uncertainty on dDEC
(dDECerr16th)
732-743 E12.7 arcsec E_dDE Upper 84th percentile uncertainty on dDEC
(dDECerr84th)
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Source Source designation (2MASS ID) (Source)
25- 36 E12.7 pc Dist Stellar distance (dist)
38- 49 E12.7 au R90med Median radius enclosing 90% of CO flux
(R90_median)
51- 62 E12.7 au e_R90med Lower 16th percentile uncertainty on R90
(R90err16th)
64- 75 E12.7 au E_R90med Upper 84th percentile uncertainty on R90
(R90err84th)
77- 88 E12.7 au R68med Median radius enclosing 68% of CO flux
(R68_median)
90-101 E12.7 au e_R68med Lower 16th percentile uncertainty on R68
(R68err16th)
103-114 E12.7 au E_R68med Upper 84th percentile uncertainty on R68
(R68err84th)
116-127 E12.7 deg inc Disk inclination (inc)
129-140 E12.7 deg e_inc Lower 16th percentile uncertainty on inc
(incerr16th)
142-153 E12.7 deg E_inc Upper 84th percentile uncertainty on inc
(incerr84th)
155-167 E13.7 deg PA [] Disk position angle (PA)
169-180 E12.7 deg e_PA Lower 16th percentile uncertainty on PA
(PAerr16th)
182-193 E12.7 deg E_PA Upper 84th percentile uncertainty on PA
(PAerr84th)
195-206 E12.7 Msun Mstar Stellar mass (M_star)
208-219 E12.7 Msun e_Mstar Lower 16th percentile uncertainty on M_star
(Mstarerr_16th)
221-232 E12.7 Msun E_Mstar Upper 84th percentile uncertainty on M_star
(Mstarerr_84th)
234-245 E12.7 au routmed Median outer disk radius (routmedian)
247-258 E12.7 au e_routmed Lower 16th percentile uncertainty on r_out
(routerr_16th)
260-271 E12.7 au E_routmed Upper 84th percentile uncertainty on r_out
(routerr_84th)
273-284 E12.7 K T10med Median midplane temperature at 10 au
(T10median)
286-297 E12.7 K e_T10med Lower 16th percentile uncertainty on T_10
(T10err_16th)
299-310 E12.7 K E_T10med Upper 84th percentile uncertainty on T_10
(T10err_84th)
312-324 E13.7 K Tqmed Median T_q (Tqmedian)
326-337 E12.7 K e_Tqmed Lower 16th percentile uncertainty on T_q
(Tqerr_16th)
339-350 E12.7 K E_Tqmed Upper 84th percentile uncertainty on T_q
(Tqerr_84th)
352-363 E12.7 --- tau10med tau parameter at 10 au (tau10median)
365-376 E12.7 --- e_tau10med Lower 16th percentile uncertainty
(tau10err_16th)
378-389 E12.7 --- E_tau10med Upper 84th percentile uncertainty
(tau10err_84th)
391-402 E12.7 m/s vsys Systemic velocity (vsys)
404-415 E12.7 m/s e_vsys Lower 16th percentile uncertainty on vsys
(vsyserr16th)
417-428 E12.7 m/s E_vsys Upper 84th percentile uncertainty on vsys
(vsyserr84th)
430-442 E13.7 arcsec dRA RA offset from phase center (dRA)
444-455 E12.7 arcsec e_dRA Lower 16th percentile uncertainty on dRA
(dRAerr16th)
457-468 E12.7 arcsec E_dRA Upper 84th percentile uncertainty on dRA
(dRAerr84th)
470-482 E13.7 arcsec dDE DEC offset from phase center (dDEC)
484-495 E12.7 arcsec e_dDE Lower 16th percentile uncertainty on dDEC
(dDECerr16th)
497-508 E12.7 arcsec E_dDE Upper 84th percentile uncertainty on dDEC
(dDECerr84th)
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Acknowledgements:
Luigi Zallio, luigi.zallio(at)unimi.it
License: CC-BY-4.0 [see https://spdx.org/licenses/]
(End) Patricia Vannier [CDS] 06-Mar-2026