Refractory Phosphorus In The HD 100546 Protoplanetary Disk

The phosphorus budget of planets is intertwined with their formation history and is thought to influence their habitability.

The chemical reservoirs and volatile vs refractory budget of phosphorus in planet-forming environments have so far eluded empirical characterisation. We employ high-resolution spectra from HST/STIS in the ultraviolet and APEX in the sub-mm to constrain the phosphorus budget in the well-characterized HD 100546 star and protoplanetary disk system. We measure log(P/H)_⋆=−7.50+0.23−0.28 on the stellar surface, which traces the total inventory of P in accreting gas and dust from the inner disk.

The inner disk gas, inside of the main dust trap, has log(P/H)_in≲−8.70, and the outer disk gas log(P/H)_out≲−9.30. Phosphorus in the disk is carried by a relatively refractory reservoir, consistent with minerals such as apatite or schreibersite, or with ammonium phosphate salts, in terms of sublimation temperature. We discuss the impact this might have on the two protoplanets around HD 100546.

Our results contribute to our understanding of the chemical habitability of planetary systems and lay a foundation for future explorations, especially in the context of JWST and Ariel which can study phosphorus in exoplanet atmospheres.

Sketch of the HD 100546 system with the star, protoplanetary disk, and two claimed protoplanets. — astro-ph.EP

Mihkel Kama, Oliver Shorttle, Sandipan P. D. Borthakur, Luke Keyte, Jennifer B. Bergner, Luca Fossati, Colin P. Folsom, Heleri Ramler

Comments: 11 pages, 7 figures, accepted for publication in MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2504.14228 [astro-ph.EP] (or arXiv:2504.14228v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2504.14228
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Submission history
From: Mihkel Kama
[v1] Sat, 19 Apr 2025 08:35:00 UTC (3,111 KB)
https://arxiv.org/abs/2504.14228
Astrobiology, Astrochemistry,