exoALMA. XIII. Gas masses from N2H+ and C18O: a comparison of measurement techniques for protoplanetary gas disk masses

Leon Trapman; Cristiano Longarini; Giovanni P. Rosotti; Sean M. Andrews; Jaehan Bae; Marcelo Barraza-Alfaro; Myriam Benisty; Gianni Cataldi; Pietro Curone; Ian Czekala; Stefano Facchini; Daniele Fasano; Mario Flock; Misato Fukagawa; Maria Galloway-Sprietsma; Himanshi Garg; Cassandra Hall; Jane Huang; John D. Ilee; Andres F. Izquierdo; Kazuhiro Kanagawa; Geoffroy Lesur; Giuseppe Lodato; Ryan A. Loomis; Ryuta Orihara; Teresa Paneque-Carreno; Christophe Pinte; Daniel Price; Jochen Stadler; Richard Teague; Sierk van Terwisga; Leonardo Testi; Hsi-Wei Yen; Gaylor Wafflard-Fernandez; David J. Wilner; Andrew J. Winter; Lisa Wölfer; Tomohiro C. Yoshida; Brianna Zawadzki; Ke Zhang

doi:10.3847/2041-8213/adc430

exoALMA. XIII. Gas masses from N₂H⁺ and C¹⁸O: a comparison of measurement techniques for protoplanetary gas disk masses

Leon Trapman^*, Cristiano Longarini, Giovanni P. Rosotti, Sean M. Andrews, Jaehan Bae, Marcelo Barraza-Alfaro, Myriam Benisty, Gianni Cataldi, Pietro Curone, Ian Czekala, Stefano Facchini, Daniele Fasano, Mario Flock, Misato Fukagawa, Maria Galloway-Sprietsma, Himanshi Garg, Cassandra Hall, Jane Huang, John D. Ilee, Andres F. IzquierdoKazuhiro Kanagawa, Geoffroy Lesur, Giuseppe Lodato, Ryan A. Loomis, Ryuta Orihara, Teresa Paneque-Carreno, Christophe Pinte, Daniel Price, Jochen Stadler, Richard Teague, Sierk van Terwisga, Leonardo Testi, Hsi-Wei Yen, Gaylor Wafflard-Fernandez, David J. Wilner, Andrew J. Winter, Lisa Wölfer, Tomohiro C. Yoshida, Brianna Zawadzki, Ke Zhang

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

The gas masses of protoplanetary disks are important but elusive quantities. In this work we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of N₂H⁺ (3–2) for 11 exoALMA disks. N2H+ is a molecule sensitive to CO freeze-out and has recently been shown to significantly improve the accuracy of gas masses estimated from CO line emission. We combine these new observations with archival N₂H⁺ and CO isotopologue observations to measure gas masses for 19 disks, predominantly from the exoALMA large program. For 15 of these disks the gas mass has also been measured using gas rotation curves. We show that the CO + N₂H⁺ line emission-based gas masses typically agree with the kinematically measured ones within a factor of 3 (∼1σ–2σ). Gas disk masses from CO + N₂H⁺ are on average a factor of 2.3^+0.7_-1.0 × lower than the kinematic disk masses, which could suggest slightly lower N2 abundances and/or lower midplane ionization rates than typically assumed. Herbig disks are found to have CO gas abundances at the level of the interstellar medium based on their CO and N₂H⁺ fluxes, which sets them apart from T Tauri disks, where abundances are typically ∼3−30× lower. The agreement between CO + N₂H⁺-based and kinematically measured gas masses is promising and shows that multimolecule line fluxes are a robust tool to accurately measure disk masses at least for extended disks.

Original language	English
Article number	L18
Number of pages	16
Journal	Astrophysical Journal Letters
Volume	984
Issue number	1
Early online date	28 Apr 2025
DOIs	https://doi.org/10.3847/2041-8213/adc430
Publication status	Published - 1 May 2025

Keywords

Protoplanetary disks
Astrochemistry
Interferometry
Radio interferometry

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Cite this

Trapman, L., Longarini, C., Rosotti, G. P., Andrews, S. M., Bae, J., Barraza-Alfaro, M., Benisty, M., Cataldi, G., Curone, P., Czekala, I., Facchini, S., Fasano, D., Flock, M., Fukagawa, M., Galloway-Sprietsma, M., Garg, H., Hall, C., Huang, J., Ilee, J. D., ... Zhang, K. (2025). exoALMA. XIII. Gas masses from N₂H⁺ and C¹⁸O: a comparison of measurement techniques for protoplanetary gas disk masses. Astrophysical Journal Letters, 984(1), Article L18. https://doi.org/10.3847/2041-8213/adc430

@article{e80acbe119f243e79e80bfe8f29c79e8,

title = "exoALMA. XIII. Gas masses from N2H+ and C18O: a comparison of measurement techniques for protoplanetary gas disk masses",

abstract = "The gas masses of protoplanetary disks are important but elusive quantities. In this work we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of N2H+ (3–2) for 11 exoALMA disks. N2H+ is a molecule sensitive to CO freeze-out and has recently been shown to significantly improve the accuracy of gas masses estimated from CO line emission. We combine these new observations with archival N2H+ and CO isotopologue observations to measure gas masses for 19 disks, predominantly from the exoALMA large program. For 15 of these disks the gas mass has also been measured using gas rotation curves. We show that the CO + N2H+ line emission-based gas masses typically agree with the kinematically measured ones within a factor of 3 (∼1σ–2σ). Gas disk masses from CO + N2H+ are on average a factor of 2.3+0.7-1.0 × lower than the kinematic disk masses, which could suggest slightly lower N2 abundances and/or lower midplane ionization rates than typically assumed. Herbig disks are found to have CO gas abundances at the level of the interstellar medium based on their CO and N2H+ fluxes, which sets them apart from T Tauri disks, where abundances are typically ∼3−30× lower. The agreement between CO + N2H+-based and kinematically measured gas masses is promising and shows that multimolecule line fluxes are a robust tool to accurately measure disk masses at least for extended disks.",

keywords = "Protoplanetary disks, Astrochemistry, Interferometry, Radio interferometry",

author = "Leon Trapman and Cristiano Longarini and Rosotti, \{Giovanni P.\} and Andrews, \{Sean M.\} and Jaehan Bae and Marcelo Barraza-Alfaro and Myriam Benisty and Gianni Cataldi and Pietro Curone and Ian Czekala and Stefano Facchini and Daniele Fasano and Mario Flock and Misato Fukagawa and Maria Galloway-Sprietsma and Himanshi Garg and Cassandra Hall and Jane Huang and Ilee, \{John D.\} and Izquierdo, \{Andres F.\} and Kazuhiro Kanagawa and Geoffroy Lesur and Giuseppe Lodato and Loomis, \{Ryan A.\} and Ryuta Orihara and Teresa Paneque-Carreno and Christophe Pinte and Daniel Price and Jochen Stadler and Richard Teague and \{van Terwisga\}, Sierk and Leonardo Testi and Hsi-Wei Yen and Gaylor Wafflard-Fernandez and Wilner, \{David J.\} and Winter, \{Andrew J.\} and Lisa W{\"o}lfer and Yoshida, \{Tomohiro C.\} and Brianna Zawadzki and Ke Zhang",

note = "Funding: L.T. and K.Z. acknowledge the support of the NSF AAG grant \#2205617. C.L. has received funding from the European Union{\textquoteright}s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 823823 (DUSTBUSTERS) and by the UK Science and Technology research Council (STFC) via the consolidated grant ST/W000997/1. G.R. acknowledges funding from the Fondazione Cariplo, grant No. 2022-1217, and the European Research Council (ERC) under the European Union{\textquoteright}s Horizon Europe Research \& Innovation Programme under grant agreement no. 101039651 (DiscEvol). J.B. acknowledges support from NASA XRP grant No. 80NSSC23K1312. M.B., D.F., and J.S. have received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation program (PROTOPLANETS, grant agreement No. 101002188). Computations have been done on the {\textquoteright}Mesocentre SIGAMM{\textquoteright} machine, hosted by Observatoire de la C{\^o}te d{\textquoteright}Azur. P.C. acknowledges support by the Italian Ministero dell{\textquoteright}Istruzione, Universit{\`a} e Ricerca through the grant Progetti Premiali 2012 - iALMA (CUP C52I13000140001) and by the ANID BASAL project FB210003. S.F. is funded by the European Union (ERC, UNVEIL, 101076613). S.F. acknowledges financial contribution from PRIN-MUR 2022YP5ACE. M.F. is supported by a Grant-in-Aid from the Japan Society for the Promotion of Science (KAKENHI: No. JP22H01274). J.D.I. acknowledges support from an STFC Ernest Rutherford Fellowship (ST/W004119/1) and a University Academic Fellowship from the University of Leeds. Support for A.F.I. was provided by NASA through the NASA Hubble Fellowship grant No. HST-HF2-51532.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. G.L. acknowledges support from the European Union{\textquoteright}s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement \#823823 (RISE DUSTBUSTERS project) and from the Italian MUR through PRIN 20228JPA3A. C.P. acknowledges Australian Research Council funding via FT170100040, DP18010423, DP220103767, and DP240103290. H.-W.Y. acknowledges support from National Science and Technology Council (NSTC) in Taiwan through grant NSTC 110-2628-M-001-003-MY3 and from the Academia Sinica Career Development Award (AS-CDA-111-M03). Support for B.Z. was provided by The Brinson Foundation. C.H. acknowledges support from the National Science Foundation Astronomy and Astrophysics Research grants program No. 2407679. A.J.W. has received funding from the European Union{\textquoteright}s Horizon 2020 research and innovation program under the Marie Sk{\l}odowska-Curie grant agreement No. 101104656.",

year = "2025",

month = may,

day = "1",

doi = "10.3847/2041-8213/adc430",

language = "English",

volume = "984",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "American Astronomical Society",

number = "1",

}

Trapman, L, Longarini, C, Rosotti, GP, Andrews, SM, Bae, J, Barraza-Alfaro, M, Benisty, M, Cataldi, G, Curone, P, Czekala, I, Facchini, S, Fasano, D, Flock, M, Fukagawa, M, Galloway-Sprietsma, M, Garg, H, Hall, C, Huang, J, Ilee, JD, Izquierdo, AF, Kanagawa, K, Lesur, G, Lodato, G, Loomis, RA, Orihara, R, Paneque-Carreno, T, Pinte, C, Price, D, Stadler, J, Teague, R, van Terwisga, S, Testi, L, Yen, H-W, Wafflard-Fernandez, G, Wilner, DJ, Winter, AJ, Wölfer, L, Yoshida, TC, Zawadzki, B & Zhang, K 2025, 'exoALMA. XIII. Gas masses from N₂H⁺ and C¹⁸O: a comparison of measurement techniques for protoplanetary gas disk masses', Astrophysical Journal Letters, vol. 984, no. 1, L18. https://doi.org/10.3847/2041-8213/adc430

TY - JOUR

T1 - exoALMA. XIII. Gas masses from N2H+ and C18O

T2 - a comparison of measurement techniques for protoplanetary gas disk masses

AU - Trapman, Leon

AU - Longarini, Cristiano

AU - Rosotti, Giovanni P.

AU - Andrews, Sean M.

AU - Bae, Jaehan

AU - Barraza-Alfaro, Marcelo

AU - Benisty, Myriam

AU - Cataldi, Gianni

AU - Curone, Pietro

AU - Czekala, Ian

AU - Facchini, Stefano

AU - Fasano, Daniele

AU - Flock, Mario

AU - Fukagawa, Misato

AU - Galloway-Sprietsma, Maria

AU - Garg, Himanshi

AU - Hall, Cassandra

AU - Huang, Jane

AU - Ilee, John D.

AU - Izquierdo, Andres F.

AU - Kanagawa, Kazuhiro

AU - Lesur, Geoffroy

AU - Lodato, Giuseppe

AU - Loomis, Ryan A.

AU - Orihara, Ryuta

AU - Paneque-Carreno, Teresa

AU - Pinte, Christophe

AU - Price, Daniel

AU - Stadler, Jochen

AU - Teague, Richard

AU - van Terwisga, Sierk

AU - Testi, Leonardo

AU - Yen, Hsi-Wei

AU - Wafflard-Fernandez, Gaylor

AU - Wilner, David J.

AU - Winter, Andrew J.

AU - Wölfer, Lisa

AU - Yoshida, Tomohiro C.

AU - Zawadzki, Brianna

AU - Zhang, Ke

N1 - Funding: L.T. and K.Z. acknowledge the support of the NSF AAG grant #2205617. C.L. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 823823 (DUSTBUSTERS) and by the UK Science and Technology research Council (STFC) via the consolidated grant ST/W000997/1. G.R. acknowledges funding from the Fondazione Cariplo, grant No. 2022-1217, and the European Research Council (ERC) under the European Union’s Horizon Europe Research & Innovation Programme under grant agreement no. 101039651 (DiscEvol). J.B. acknowledges support from NASA XRP grant No. 80NSSC23K1312. M.B., D.F., and J.S. have received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (PROTOPLANETS, grant agreement No. 101002188). Computations have been done on the ’Mesocentre SIGAMM’ machine, hosted by Observatoire de la Côte d’Azur. P.C. acknowledges support by the Italian Ministero dell’Istruzione, Università e Ricerca through the grant Progetti Premiali 2012 - iALMA (CUP C52I13000140001) and by the ANID BASAL project FB210003. S.F. is funded by the European Union (ERC, UNVEIL, 101076613). S.F. acknowledges financial contribution from PRIN-MUR 2022YP5ACE. M.F. is supported by a Grant-in-Aid from the Japan Society for the Promotion of Science (KAKENHI: No. JP22H01274). J.D.I. acknowledges support from an STFC Ernest Rutherford Fellowship (ST/W004119/1) and a University Academic Fellowship from the University of Leeds. Support for A.F.I. was provided by NASA through the NASA Hubble Fellowship grant No. HST-HF2-51532.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. G.L. acknowledges support from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement #823823 (RISE DUSTBUSTERS project) and from the Italian MUR through PRIN 20228JPA3A. C.P. acknowledges Australian Research Council funding via FT170100040, DP18010423, DP220103767, and DP240103290. H.-W.Y. acknowledges support from National Science and Technology Council (NSTC) in Taiwan through grant NSTC 110-2628-M-001-003-MY3 and from the Academia Sinica Career Development Award (AS-CDA-111-M03). Support for B.Z. was provided by The Brinson Foundation. C.H. acknowledges support from the National Science Foundation Astronomy and Astrophysics Research grants program No. 2407679. A.J.W. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 101104656.

PY - 2025/5/1

Y1 - 2025/5/1

N2 - The gas masses of protoplanetary disks are important but elusive quantities. In this work we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of N2H+ (3–2) for 11 exoALMA disks. N2H+ is a molecule sensitive to CO freeze-out and has recently been shown to significantly improve the accuracy of gas masses estimated from CO line emission. We combine these new observations with archival N2H+ and CO isotopologue observations to measure gas masses for 19 disks, predominantly from the exoALMA large program. For 15 of these disks the gas mass has also been measured using gas rotation curves. We show that the CO + N2H+ line emission-based gas masses typically agree with the kinematically measured ones within a factor of 3 (∼1σ–2σ). Gas disk masses from CO + N2H+ are on average a factor of 2.3+0.7-1.0 × lower than the kinematic disk masses, which could suggest slightly lower N2 abundances and/or lower midplane ionization rates than typically assumed. Herbig disks are found to have CO gas abundances at the level of the interstellar medium based on their CO and N2H+ fluxes, which sets them apart from T Tauri disks, where abundances are typically ∼3−30× lower. The agreement between CO + N2H+-based and kinematically measured gas masses is promising and shows that multimolecule line fluxes are a robust tool to accurately measure disk masses at least for extended disks.

AB - The gas masses of protoplanetary disks are important but elusive quantities. In this work we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of N2H+ (3–2) for 11 exoALMA disks. N2H+ is a molecule sensitive to CO freeze-out and has recently been shown to significantly improve the accuracy of gas masses estimated from CO line emission. We combine these new observations with archival N2H+ and CO isotopologue observations to measure gas masses for 19 disks, predominantly from the exoALMA large program. For 15 of these disks the gas mass has also been measured using gas rotation curves. We show that the CO + N2H+ line emission-based gas masses typically agree with the kinematically measured ones within a factor of 3 (∼1σ–2σ). Gas disk masses from CO + N2H+ are on average a factor of 2.3+0.7-1.0 × lower than the kinematic disk masses, which could suggest slightly lower N2 abundances and/or lower midplane ionization rates than typically assumed. Herbig disks are found to have CO gas abundances at the level of the interstellar medium based on their CO and N2H+ fluxes, which sets them apart from T Tauri disks, where abundances are typically ∼3−30× lower. The agreement between CO + N2H+-based and kinematically measured gas masses is promising and shows that multimolecule line fluxes are a robust tool to accurately measure disk masses at least for extended disks.

KW - Protoplanetary disks

KW - Astrochemistry

KW - Interferometry

KW - Radio interferometry

UR - https://www.scopus.com/pages/publications/105004229960

U2 - 10.3847/2041-8213/adc430

DO - 10.3847/2041-8213/adc430

M3 - Article

AN - SCOPUS:105004229960

SN - 2041-8205

VL - 984

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

M1 - L18

ER -

exoALMA. XIII. Gas masses from N₂H⁺ and C¹⁸O: a comparison of measurement techniques for protoplanetary gas disk masses

Abstract

Keywords

Access to Document

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Fingerprint

2D T-Tauri disk models for CO isotopologue and N2H+ lines

exoALMA. I. Science goals, project design, and data products

exoALMA. II. Data calibration and imaging pipeline

exoALMA. III. Line-intensity modeling and system property extraction from protoplanetary disks

Cite this

exoALMA. XIII. Gas masses from N2H+ and C18O: a comparison of measurement techniques for protoplanetary gas disk masses

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Datasets

2D T-Tauri disk models for CO isotopologue and N2H+ lines

Research output

exoALMA. I. Science goals, project design, and data products

exoALMA. II. Data calibration and imaging pipeline

exoALMA. III. Line-intensity modeling and system property extraction from protoplanetary disks

Cite this

exoALMA. XIII. Gas masses from N₂H⁺ and C¹⁸O: a comparison of measurement techniques for protoplanetary gas disk masses