Masses of Potentially Habitable Planets Characterized by the Habitable Worlds Observatory

Fuente: arXiv
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Autori principali: Gary, Kaz, Gaudi, B. Scott, Bendek, Eduardo, Robinson, Tyler, Hu, Renyu, Sitarski, Breann, Roberge, Aki, Mamajek, Eric
Natura: Preprint
Pubblicazione: 2026
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author Gary, Kaz
Gaudi, B. Scott
Bendek, Eduardo
Robinson, Tyler
Hu, Renyu
Sitarski, Breann
Roberge, Aki
Mamajek, Eric
author_facet Gary, Kaz
Gaudi, B. Scott
Bendek, Eduardo
Robinson, Tyler
Hu, Renyu
Sitarski, Breann
Roberge, Aki
Mamajek, Eric
contents Constraints on the masses of exoplanets directly imaged and characterized by the Habitable Worlds Observatory (HWO) are crucial for categorizing these planets and interpreting their spectra. In particular, achieving a mass measurement with a precision of approximately 10% or better may be necessary to identify the dominant gaseous species in the atmospheres of Earth-like planets. This is essential for assessing their habitability and interpreting potential biosignatures (arXiv:2502.01513). Space-based astrometry will be required to measure the masses of planets in face-on systems, or planets orbiting hot and rapidly rotating or highly active stars. Astrometric uncertainties are dominated by the number and magnitude of background reference stars needed to precisely measure the astrometric wobble of the target star induced by the planet. To that end, we propose a program to measure the masses of Earth analogs orbiting HWO target stars with ultra-high-precision astrometry obtained with the HWO high-resolution instrument. We assess the photon-noise error budget for these observations. We find that, for a field of view spanning a few square arcminutes, the astrometric uncertainty due to the number and brightness of reference stars dominates the photon-noise error budget, particularly for targets near the Galactic poles. We explored the impact of filter choice and location in the sky on the photon-noise astrometric uncertainties by simulating the magnitude distribution of reference stars across different filters at a range of galactic longitudes and latitudes. We find that a ~ 200-day survey in the Gaia G band consisting of 100 epochs per target star distributed over the 5-year prime mission with a 6m aperture HWO equipped with a 6' x 6' field-of-view would be required to achieve the photon-noise sensitivity to measure the masses of the ~ 40 Earth-mass habitable-zone planets to ~10%.
format Preprint
id arxiv_https___arxiv_org_abs_2603_11146
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Masses of Potentially Habitable Planets Characterized by the Habitable Worlds Observatory
Gary, Kaz
Gaudi, B. Scott
Bendek, Eduardo
Robinson, Tyler
Hu, Renyu
Sitarski, Breann
Roberge, Aki
Mamajek, Eric
Instrumentation and Methods for Astrophysics
Earth and Planetary Astrophysics
Constraints on the masses of exoplanets directly imaged and characterized by the Habitable Worlds Observatory (HWO) are crucial for categorizing these planets and interpreting their spectra. In particular, achieving a mass measurement with a precision of approximately 10% or better may be necessary to identify the dominant gaseous species in the atmospheres of Earth-like planets. This is essential for assessing their habitability and interpreting potential biosignatures (arXiv:2502.01513). Space-based astrometry will be required to measure the masses of planets in face-on systems, or planets orbiting hot and rapidly rotating or highly active stars. Astrometric uncertainties are dominated by the number and magnitude of background reference stars needed to precisely measure the astrometric wobble of the target star induced by the planet. To that end, we propose a program to measure the masses of Earth analogs orbiting HWO target stars with ultra-high-precision astrometry obtained with the HWO high-resolution instrument. We assess the photon-noise error budget for these observations. We find that, for a field of view spanning a few square arcminutes, the astrometric uncertainty due to the number and brightness of reference stars dominates the photon-noise error budget, particularly for targets near the Galactic poles. We explored the impact of filter choice and location in the sky on the photon-noise astrometric uncertainties by simulating the magnitude distribution of reference stars across different filters at a range of galactic longitudes and latitudes. We find that a ~ 200-day survey in the Gaia G band consisting of 100 epochs per target star distributed over the 5-year prime mission with a 6m aperture HWO equipped with a 6' x 6' field-of-view would be required to achieve the photon-noise sensitivity to measure the masses of the ~ 40 Earth-mass habitable-zone planets to ~10%.
title Masses of Potentially Habitable Planets Characterized by the Habitable Worlds Observatory
topic Instrumentation and Methods for Astrophysics
Earth and Planetary Astrophysics
url https://arxiv.org/abs/2603.11146