Exomoons and Exorings with the Habitable Worlds Observatory II: Finding Endor with Lunar Eclipses

Fuente: arXiv
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Hauptverfasser: Limbach, Mary Anne, Dacus, Beck, Kotten, Brooke, Lane, Elizabeth, Lustig-Yaeger, Jacob, MacDonald, Ryan, Robinson, Tyler D., Ruffio, Jean-Baptiste, Vanderburg, Andrew
Format: Preprint
Veröffentlicht: 2026
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author Limbach, Mary Anne
Dacus, Beck
Kotten, Brooke
Lane, Elizabeth
Lustig-Yaeger, Jacob
MacDonald, Ryan
Robinson, Tyler D.
Ruffio, Jean-Baptiste
Vanderburg, Andrew
author_facet Limbach, Mary Anne
Dacus, Beck
Kotten, Brooke
Lane, Elizabeth
Lustig-Yaeger, Jacob
MacDonald, Ryan
Robinson, Tyler D.
Ruffio, Jean-Baptiste
Vanderburg, Andrew
contents Giant planets in the habitable zone may host exomoons with conditions conducive to life. In this paper we describe a method by which the Habitable Worlds Observatory (HWO) could detect such moons: broadband reflected-light lunar eclipses (e.g., the moon passing into the shadow of the planet). We find that an Earth-like moon orbiting a Jovian-size planet at 1au can outshine its host planet near 1 micron, producing frequent (days time-scale) lunar eclipses with depths of order 50%. We determine that single eclipse events out to $\sim$12pc may be detectable for Earth-like moons around giant planets, down to $0.9R_\oplus$. Detection of smaller moons, $\sim$0.5$R_\oplus$ (corresponding to about the size of Mars or Ganymede), may be possible, but would generally require multiple events for most systems. These several-hour events provide a clear pathway to detecting habitable moons with HWO, given sufficient stare-time on each system to detect lunar eclipses. The occurrence rate of habitable exomoons remains unconstrained, however, making the ultimate yield uncertain. HWO will be capable of placing the first meaningful constraints on the frequency of habitable exomoons around giant planets; if it is non-negligible, HWO could also search for life on these worlds, possibly with lunar eclipse spectroscopy.
format Preprint
id arxiv_https___arxiv_org_abs_2601_20002
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Exomoons and Exorings with the Habitable Worlds Observatory II: Finding Endor with Lunar Eclipses
Limbach, Mary Anne
Dacus, Beck
Kotten, Brooke
Lane, Elizabeth
Lustig-Yaeger, Jacob
MacDonald, Ryan
Robinson, Tyler D.
Ruffio, Jean-Baptiste
Vanderburg, Andrew
Earth and Planetary Astrophysics
Giant planets in the habitable zone may host exomoons with conditions conducive to life. In this paper we describe a method by which the Habitable Worlds Observatory (HWO) could detect such moons: broadband reflected-light lunar eclipses (e.g., the moon passing into the shadow of the planet). We find that an Earth-like moon orbiting a Jovian-size planet at 1au can outshine its host planet near 1 micron, producing frequent (days time-scale) lunar eclipses with depths of order 50%. We determine that single eclipse events out to $\sim$12pc may be detectable for Earth-like moons around giant planets, down to $0.9R_\oplus$. Detection of smaller moons, $\sim$0.5$R_\oplus$ (corresponding to about the size of Mars or Ganymede), may be possible, but would generally require multiple events for most systems. These several-hour events provide a clear pathway to detecting habitable moons with HWO, given sufficient stare-time on each system to detect lunar eclipses. The occurrence rate of habitable exomoons remains unconstrained, however, making the ultimate yield uncertain. HWO will be capable of placing the first meaningful constraints on the frequency of habitable exomoons around giant planets; if it is non-negligible, HWO could also search for life on these worlds, possibly with lunar eclipse spectroscopy.
title Exomoons and Exorings with the Habitable Worlds Observatory II: Finding Endor with Lunar Eclipses
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2601.20002