Requirements For Joint Orbital Characterization of Cold Giants and Habitable Worlds with Habitable Worlds Observatory

We determine optimal requirements for the joint detection of habitable-zone planets and cold giant planets with the Habitable Worlds Observatory (HWO).

Analysis of 164 nearby stars shows that a coronagraph outer working angle (OWA) of 1440 milliarcseconds (mas) is necessary to achieve 80-90% visibility of cold giants. Approximately 40 precursor radial velocity measurements with 1 m/s precision are required to adequately constrain orbital parameters before HWO observations.

We demonstrate that 6-8 astrometric measurements distributed across the mission timeline, compared to radial velocity constraints alone and to astrometry constraints alone, significantly improve orbital parameter precision, enabling direct determination of orbital inclination with uncertainties of 0.8-3 degrees.

For habitable-zone planet characterization, 4-5 epochs provide moderate confidence, while high-confidence (95%) confirmation requires 8+ observations.

These specifications are essential for the comprehensive characterization of planetary system architectures and understanding the potential habitability of terrestrial exoplanets.

Sabina Sagynbayeva, Asif Abbas, Stephen R. Kane, Eric L. Nielsen, William Thompson, Sarah Blunt, Malena Rice, Jessie L. Christiansen, Caleb K. Harada, Elisabeth R. Newton, Yasuhiro Hasegawa, Philip J. Armitage, Tansu Daylan

Comments: In review in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2507.21443 [astro-ph.EP] (or arXiv:2507.21443v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.21443
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Submission history
From: Sabina Sagynbayeva
[v1] Tue, 29 Jul 2025 02:32:25 UTC (13,631 KB)
https://arxiv.org/abs/2507.21443

Astrobiology,