Imaging Venus-like Worlds: Spectral, Polarimetric, And UV Diagnostics For The Habitable Worlds Observatory

Understanding planetary habitability requires a comparative approach that explores the divergent evolutionary outcomes of Earth and Venus.

The Habitable Worlds Observatory (HWO) will be uniquely positioned to conduct a statistical and physical census of terrestrial exoplanets spanning the Venus Zone (VZ) and the Habitable Zone (HZ), enabling the detection and atmospheric characterization of post-runaway greenhouse worlds (“exoVenuses”).

We present an updated list of VZ exoplanets, which raises the number of known candidates to 370. We describe a science case and an observing strategy for VZ exoplanets that integrates precursor exoplanet detection data and stellar characterization with HWO direct imaging, spectroscopy across the UV/optical/IR, and spectropolarimetry.

Our proposed framework emphasizes a pathway toward the diagnosis of sulfur chemistry (SO₂) and aerosol physics (H₂SO₄ clouds/hazes), planetary redox states (O₂/O₃ false positives from hydrogen loss), and cloud microphysics detection (rainbow polarization).

We quantify implications for HWO requirements, including UV access to 0.2–0.4 μm, optical/NIR coverage to ≳1.5 μm, inner working angle (IWA) reaching 0.3–1.5 AU around nearby Sun-like stars, and the SNR/resolution needed for key features. Finally, we outline a community-driven path to producing robust demographic inferences and target selection for optimizing HWO observations.

Stephen R. Kane, Kimberly M. Bott, Kenneth E. Goodis Gordon, Emma L. Miles, Colby M. Ostberg, Paul K. Byrne, Ludmila Carone, Tansu Daylan, Antonio Garcia Munoz, Caleb K. Harada, Renyu Hu, Noam. R. Izenberg, Erika Kohler, Malena Rice, Sabina Sagynbayeva, Manuel Scherf, Edward W. Schwieterman, Peter Woitke

Comments: 15 pages, 5 figures, 2 tables, accepted for publication in PASP
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2602.02728 [astro-ph.EP] (or arXiv:2602.02728v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2602.02728
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Submission history
From: Stephen Kane
[v1] Mon, 2 Feb 2026 19:43:55 UTC (2,247 KB)
https://arxiv.org/abs/2602.02728

Astrobiology, exoplanet,