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An inherited complex organic molecule reservoir in a warm planet-hosting disk


Quantifying the composition of the material in protoplanetary disks is essential to determining the potential for exoplanetary systems to produce and support habitable environments. When considering potential habitability, complex organic molecules are relevant, key among which is methanol (CH3OH). Methanol primarily forms at low temperatures via the hydrogenation of CO ice on the surface of icy dust grains and is a necessary basis for the formation of more complex species such as amino acids and proteins. We report the detection of CH3OH in a disk around a young, luminous A-type star, HD 100546. This disk is warm and therefore does not host an abundant reservoir of CO ice. We argue that the CH3OH cannot form in situ, and hence that this disk has probably inherited complex-organic-molecule-rich ice from an earlier cold dark cloud phase. This is strong evidence that at least some interstellar organic material survives the disk-formation process and can then be incorporated into forming planets, moons and comets. Therefore, crucial pre-biotic chemical evolution already takes place in dark star-forming clouds.

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Fig. 1: The detected CH3OH emission lines in the HD 100546 disk.
Fig. 2: A comparison of the HD 100546 CH3OH-to-H2CO ratio with other sources.
Fig. 3: Model gas- and ice-phase CH3OH column density in the HD 100546 disk as a function of disk radius and time.
Fig. 4: Cartoon of the HD 100546 disk structure.

Data availability

The data presented here are from the ongoing ALMA Cycle 7 Program 2019.1.00193.S (PI A.S.B.). The raw data will be made publicly available from 30 June 2021 via the ALMA archive. The scripts for self-calibration and imaging, and the reduced data (self-calibrated measurement sets) are available on request from the corresponding author. The final imaging products (channel maps) are available from VizieR.

Code availability

The HD 100546 disk physical structure model is publicly available at The chemical code is available on request from the corresponding author.


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A.S.B. acknowledges the studentship funded by the Science and Technology Facilities Council of the United Kingdom (STFC). C.W. acknowledges financial support from the University of Leeds, the Science and Technology Facilities Council, and UK Research and Innovation (grant numbers ST/R000549/1, ST/T000287/1, and MR/T040726/1). J.T.v.S. is supported by the Dutch Astrochemistry II programme of the Netherlands Organization for Scientific Research (648.000.025). J.D.I. acknowledges support from the Science and Technology Facilities Council of the United Kingdom (STFC) under grant number ST/T000287/1. M.K. was supported by the University of Tartu ASTRA project 2014-2020.4.01.16-0029 KOMEET, financed by the EU European Regional Development Fund. H.N. is supported by MEXT/JSPS KAKENHI grant numbers 18H05441, 19K03910 and 20H00182, and NAOJ ALMA Scientific Research grant number 2018-10B.

Author information




A.S.B. reduced the data, ran the chemical models, analysed both the data and model output, and wrote the manuscript. C.W. contributed to the writing of the manuscript and provided the chemical model. J.T.v.S. provided analysis scripts for the data and contributed to the manuscript. E.F.v.D, J.D.I., M.R.H. and H.N. contributed to the writing of the manuscript. M.K. provided the HD 100546 disk model and contributed to the manuscript.

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Correspondence to Alice S. Booth.

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The authors declare no competing interests.

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Supplementary Figs. 1–8 and Tables 1 and 2.

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Booth, A.S., Walsh, C., Terwisscha van Scheltinga, J. et al. An inherited complex organic molecule reservoir in a warm planet-hosting disk. Nat Astron 5, 684–690 (2021).

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