The ALMA Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO): Formaldehyde (H2CO) Emission And Its Links To Disk Properties

Protoplanetary disks are rotating structures of gas and dust surrounding young stars, serving as the birth places of planets. Understanding the chemical evolution of organic materials in these disks is key for tracing the origins of organics in planetary systems. Formaldehyde (H₂CO) is the most commonly detected organic molecule in protoplanetary disks.

In this study, we investigate the emission of H₂CO and its link to disk properties, using a sample of 20 Class II disks in the Lupus and Upper Sco star-forming regions spanning over 1-6 Myr. We analyze the H₂CO lines at 218.222 and 290.623 GHz observed as part of the AGE-PRO ALMA Large Program. Within this sample we achieve a detection rate of H₂CO of 45% (9/20), and set robust upper limits for the non-detections.

We measure the excitation temperature and column density of the H₂CO gas in the sources with H2CO detections. We combine our sample with 13 additional disks with archival H₂CO detections and search for correlations between H₂CO properties and disk parameters.

Notably, we find strong correlations between H₂CO line luminosity and dust radius, gas radius, dust mass, gas mass, stellar mass, and stellar luminosity. This suggests that H₂CO emission is brighter for extended massive dust disks where H2CO can form via CO ice hydrogenation on grain surfaces.

We find that the H₂CO excitation temperature is also correlated with stellar mass and stellar luminosity, so more massive and luminous stars could increase H₂CO excitation.

Ella Chevalier, Ke Zhang, Miguel Vioque, Nicolás T. Kurtovic, Paola Pinilla, James Miley, Dingshan Deng, John Carpenter, Carolina Agurto-Gangas, Anibal Sierra

Comments: 24 pages, 10 figures. Accepted for publication in The Astrophysical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2606.05132 [astro-ph.EP] (or arXiv:2606.05132v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2606.05132
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Submission history
From: Ella Chevalier
[v1] Wed, 3 Jun 2026 17:37:22 UTC (11,470 KB)
https://arxiv.org/abs/2606.05132
Astrobiology, Astrogeology, Astrochemistry,