• DOI:10.3847/2041-8213/ac1e2d
• Corpus ID: 237213523

On the Detection of Exomoons Transiting Isolated Planetary-mass Objects

@article{Limbach2021OnTD,
  title={On the Detection of Exomoons Transiting Isolated Planetary-mass Objects},
  author={Mary Anne Limbach and Johanna M. Vos and Joshua N. Winn and Ren{\'e} Heller and Jeffrey C. Mason and Adam C. Schneider and Fei Dai},
  journal={The Astrophysical Journal Letters},
  year={2021},
  volume={918}
}

• M. Limbach, J. Vos, +4 authors F. Dai
• Published 18 August 2021
• Physics, Geology
• The Astrophysical Journal Letters

All-sky imaging surveys have identified several dozen isolated planetary-mass objects (IPMOs) far away from any star. Here we examine the prospects for detecting transiting moons around these objects. We expect transiting moons to be common, occurring around 10%–15% of IPMOs, given that close-orbiting moons have a high geometric transit probability and are expected to be a common outcome of giant planet formation. The IPMOs offer an advantage over other directly imaged planets in that high-contrast imaging is not necessary to detect the photometric transit signal. For at least 30 (>50%) of the currently known IPMOs, observations of a single transit with the James Webb Space Telescope would have low enough forecast noise levels to allow for the detection of an Io- or Titan-like moon. The intrinsic variability of the IPMOs will be an obstacle. Using archival time-series photometry of IPMOs with the Spitzer Space Telescope as a proof of concept, we found evidence for a fading event of 2MASS J1119–1137 AB that might have been caused by intrinsic variability but is also consistent with a single transit of a habitable-zone 1.7 R ⊕ exomoon. Although the interpretation of this particular event is inconclusive, the characteristics of the data and the candidate signal suggest that Earth-sized habitable-zone exomoons around IPMOs are detectable with existing instrumentation.