Probing The Origin Of Water In Planets Within Habitable Zones By Habitable Worlds Observatory

How do habitable environments arise and evolve within the context of their planetary systems? This is one fundamental question, and it can be addressed partly by identifying how planets in habitable zones obtain water.

Historically, astronomers considered that water was delivered to the Earth via dynamical shake-up by Jupiter, which took place during the formation and post-formation eras (e.g., ≲100 Myr).

This hypothesis has recently been challenged by a more dynamic view of planet formation; planet-forming materials move in protoplanetary disks via various physical processes such as pebble drift and planetary migration.

Habitable Worlds Observatory (HWO) will open a new window to address this important, but difficult question by discovering and characterizing Earth-like exoplanets around G-type stars. In this article, we consider two possible working hypotheses: (1) the abundance of water on planets in habitable zones has any correlation with the presence of outer planets; and (2) the abundance of water on planets in habitable zones has no correlation with the presence of outer planets.

We discuss what physical parameters need to be measured to differentiate these two hypotheses and what observational capabilities are desired for HWO to reliably constrain these physical parameters.

Yasuhiro Hasegawa, Courtney Dressing, Ludmila Carone

Comments: 3 pages; the proceeding of the HWO25 conference
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2510.07349 [astro-ph.IM](or arXiv:2510.07349v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2510.07349
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Submission history
From: Yasuhiro Hasegawa
[v1] Tue, 7 Oct 2025 22:54:42 UTC (36 KB)
https://arxiv.org/abs/2510.07349
Astrobiology,