Molecular emission is used to investigate both the physical and chemical properties of protoplanetary disks. Therefore, to derive disk properties accurately, we need a thorough understanding of the behavior of the molecular probes upon which we rely. Here we investigate how the molecular line emission of N2H+, HCO+, HCN, and C18O compare to other measured quantities in a set of 20 protoplanetary disks. Overall, we find positive correlations between multiple line fluxes and the disk dust mass and radius. We also generally find strong positive correlations between the line fluxes of different molecular species. However, some disks do show noticeable differences in the relative fluxes of N2H+, HCO+, HCN, and C18O. These differences occur even within a single star-forming region. This results in a potentially large range of different disk masses and chemical compositions for systems of similar age and birth environment. While we make preliminary comparisons of molecular fluxes across different star-forming regions, more complete and uniform samples are needed in the future to search for trends with birth environment or age.
Molecular Gas Tracers in Young and Old Protoplanetary Disks
Abstract
Copyright and License
© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
We thank the anonymous referee for feedback and suggestions. D.E.A. acknowledges support from the Virginia Initiative on Cosmic Origins (VICO) Postdoctoral and Carnegie Postdoctoral Fellowships. L.I.C. gratefully acknowledges support from the David and Lucille Packard Foundation, the Virginia Space Grant Consortium, Johnson & Johnson's WiSTEM2D Award, and NSF AAG grant number AST-1910106. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2015.1.01199.S, ADS/JAO.ALMA#2018.1.01623.S, and ADS/JAO.ALMA#2019.1.01135.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This paper also makes use of data from Submillimeter Array project 2018B-S046. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics, and is funded by the Smithsonian Institution and the Academia Sinica. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Software References
Astropy (Astropy Collaboration et al. 2013; Price-Whelan et al. 2018), CASA (McMullin et al. 2007), linmix (https://github.com/jmeyers314/linmix), Matplotlib (Hunter 2007), and Numpy (van der Walt et al. 2011)
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Additional details
- ISSN
- 1538-4357
- University of Virginia
- Virginia Initiative on Cosmic Origins
- Carnegie Institution for Science
- David and Lucile Packard Foundation
- Virginia Space Grant Consortium
- Johnson and Johnson Foundation
- WiSTEM2D award
- National Science Foundation
- AST-1910106
- Smithsonian Institution
- Academia Sinica
- European Space Agency
- Gaia Multilateral Agreement
- Caltech groups
- Division of Geological and Planetary Sciences