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Title: An ALMA Survey of CO Isotopologue Emission from Protoplanetary Disks in Chamaeleon I

Abstract

The mass of a protoplanetary disk limits the formation and future growth of any planet. Masses of protoplanetary disks are usually calculated from measurements of the dust continuum emission by assuming an interstellar gas-to-dust ratio. To investigate the utility of CO as an alternate probe of disk mass, we use ALMA to survey {sup 13}CO and C{sup 18}O J = 3–2 line emission from a sample of 93 protoplanetary disks around stars and brown dwarfs with masses from in the nearby Chamaeleon I star-forming region. We detect {sup 13}CO emission from 17 sources and C{sup 18}O from only one source. Gas masses for disks are then estimated by comparing the CO line luminosities to results from published disk models that include CO freeze-out and isotope-selective photodissociation. Under the assumption of a typical interstellar medium CO-to-H{sub 2} ratio of 10{sup −4}, the resulting gas masses are implausibly low, with an average gas mass of ∼0.05 M {sub Jup} as inferred from the average flux of stacked {sup 13}CO lines. The low gas masses and gas-to-dust ratios for Cha I disks are both consistent with similar results from disks in the Lupus star-forming region. The faint CO line emission may instead bemore » explained if disks have much higher gas masses, but freeze-out of CO or complex C-bearing molecules is underestimated in disk models. The conversion of CO flux to CO gas mass also suffers from uncertainties in disk structures, which could affect gas temperatures. CO emission lines will only be a good tracer of the disk mass when models for C and CO depletion are confirmed to be accurate.« less

Authors:
;  [1]; ; ; ;  [2]; ;  [3];  [4];  [5];  [6]
  1. Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, 100871 Beijing (China)
  2. Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States)
  3. Imperial College London, London SW7 2AZ (United Kingdom)
  4. ESO/European Southern Observatory, Garching bei München (Germany)
  5. Max Planck Institute for Astronomy, Heidelberg (Germany)
  6. Scientific Support Office, Directorate of Science, European Space Research and Technology Centre (ESA/ESTEC), Noordwijk (Netherlands)
Publication Date:
OSTI Identifier:
22663344
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 844; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON 13; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; CONVERSION; COSMIC DUST; DISSOCIATION; EMISSION; FREEZING OUT; HYDROGEN; LUMINOSITY; MASS; MOLECULES; PHOTOLYSIS; PLANETS; PROTOPLANETS; STARS

Citation Formats

Long Feng, Herczeg, Gregory J., Pascucci, Ilaria, Apai, Daniel, Hendler, Nathan, Mulders, Gijs D., Drabek-Maunder, Emily, Mohanty, Subhanjoy, Testi, Leonardo, Henning, Thomas, and Manara, Carlo F., E-mail: longfeng@pku.edu.cn. An ALMA Survey of CO Isotopologue Emission from Protoplanetary Disks in Chamaeleon I. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA78FC.
Long Feng, Herczeg, Gregory J., Pascucci, Ilaria, Apai, Daniel, Hendler, Nathan, Mulders, Gijs D., Drabek-Maunder, Emily, Mohanty, Subhanjoy, Testi, Leonardo, Henning, Thomas, & Manara, Carlo F., E-mail: longfeng@pku.edu.cn. An ALMA Survey of CO Isotopologue Emission from Protoplanetary Disks in Chamaeleon I. United States. doi:10.3847/1538-4357/AA78FC.
Long Feng, Herczeg, Gregory J., Pascucci, Ilaria, Apai, Daniel, Hendler, Nathan, Mulders, Gijs D., Drabek-Maunder, Emily, Mohanty, Subhanjoy, Testi, Leonardo, Henning, Thomas, and Manara, Carlo F., E-mail: longfeng@pku.edu.cn. Tue . "An ALMA Survey of CO Isotopologue Emission from Protoplanetary Disks in Chamaeleon I". United States. doi:10.3847/1538-4357/AA78FC.
@article{osti_22663344,
title = {An ALMA Survey of CO Isotopologue Emission from Protoplanetary Disks in Chamaeleon I},
author = {Long Feng and Herczeg, Gregory J. and Pascucci, Ilaria and Apai, Daniel and Hendler, Nathan and Mulders, Gijs D. and Drabek-Maunder, Emily and Mohanty, Subhanjoy and Testi, Leonardo and Henning, Thomas and Manara, Carlo F., E-mail: longfeng@pku.edu.cn},
abstractNote = {The mass of a protoplanetary disk limits the formation and future growth of any planet. Masses of protoplanetary disks are usually calculated from measurements of the dust continuum emission by assuming an interstellar gas-to-dust ratio. To investigate the utility of CO as an alternate probe of disk mass, we use ALMA to survey {sup 13}CO and C{sup 18}O J = 3–2 line emission from a sample of 93 protoplanetary disks around stars and brown dwarfs with masses from in the nearby Chamaeleon I star-forming region. We detect {sup 13}CO emission from 17 sources and C{sup 18}O from only one source. Gas masses for disks are then estimated by comparing the CO line luminosities to results from published disk models that include CO freeze-out and isotope-selective photodissociation. Under the assumption of a typical interstellar medium CO-to-H{sub 2} ratio of 10{sup −4}, the resulting gas masses are implausibly low, with an average gas mass of ∼0.05 M {sub Jup} as inferred from the average flux of stacked {sup 13}CO lines. The low gas masses and gas-to-dust ratios for Cha I disks are both consistent with similar results from disks in the Lupus star-forming region. The faint CO line emission may instead be explained if disks have much higher gas masses, but freeze-out of CO or complex C-bearing molecules is underestimated in disk models. The conversion of CO flux to CO gas mass also suffers from uncertainties in disk structures, which could affect gas temperatures. CO emission lines will only be a good tracer of the disk mass when models for C and CO depletion are confirmed to be accurate.},
doi = {10.3847/1538-4357/AA78FC},
journal = {Astrophysical Journal},
number = 2,
volume = 844,
place = {United States},
year = {Tue Aug 01 00:00:00 EDT 2017},
month = {Tue Aug 01 00:00:00 EDT 2017}
}