Habitable Planets Eclipsing Brown Dwarfs: Strategies for Detection and Characterization

Abstract

Given the very close proximity of their habitable zones, brown dwarfs represent high-value targets in the search for nearby transiting habitable planets that may be suitable for follow-up occultation spectroscopy. In this paper we develop search strategies to find habitable planets transiting brown dwarfs depending on their maximum habitable orbital period (PHZ out). Habitable planets with PHZ out shorter than the useful duration of a night (e.g. 8-10 hrs) can be screened with 100 percent completeness from a single location and in a single night (near-IR). More luminous brown dwarfs require continuous monitoring for longer duration, e.g. from space or from a longitude-distributed network (one test scheduling achieved - 3 telescopes, 13.5 contiguous hours). Using a simulated survey of the 21 closest known brown dwarfs (within 7 pc) we find that the probability of detecting at least one transiting habitable planet is between 4.5 +5.6-1.4 and 56 +31-13 percent, depending on our assumptions. We calculate that brown dwarfs within 5-10 pc are characterizable for potential biosignatures with a 6.5 m space telescope using approx. 1 percent of a 5-year mission's life-time spread over a contiguous segment only one fifth to one tenth of this duration.

v3: corrected Table 2 and Fig. 4. v2: additional references Sect. 2 par. 1 & end of Sect. 6. 12 pages, 5 figures, 2 tables, accepted to The Astrophysical Journal (ApJ)

References in corpus (15)

• The Hubble Ultra Deep Field
• Habitable planets around the star Gl 581?
• The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface Gravity
• Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b
• Strong Water Absorption in the Dayside Emission Spectrum of the Planet HD 189733b
• A decreased probability of habitable planet formation around low-mass stars
• Tidal Heating of Terrestrial Extra-Solar Planets and Implications for their Habitability
• The potential for Earth-mass planet formation around brown dwarfs
• Could we identify hot Ocean-Planets with CoRoT, Kepler and Doppler velocimetry?
• Near Infrared Monitoring of Ultracool Dwarfs: Prospects for Searching for Transiting Companions
• Detecting Life-bearing Extra-solar Planets with Space Telescopes
• The very nearby M/T dwarf binary SCR 1845-6357
• Extremely faint high proper motion objects from SDSS stripe 82 - Optical classification spectroscopy of about 40 new objects
• Observational Window Functions in Planet Transit Surveys
• Mid-infrared imaging of brown dwarfs in binary systems

Cited by in corpus (16)

• Water loss from Earth-sized planets in the habitable zones of ultracool dwarfs: Implications for the planets of TRAPPIST-1
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs II: Properties of 11 T-dwarfs
• Fast-evolving weather for the coolest of our two new substellar neighbours
• Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary
• Brown dwarf disks with ALMA
• Formation and composition of planets around very low mass stars
• Habitability of planets on eccentric orbits: the limits of the mean flux approximation
• Astrometric planet search around southern ultracool dwarfs I: First results, including parallaxes of 20 M8-L2 dwarfs
• Ionisation in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events
• Solar System Moons as Analogs for Compact Exoplanetary Systems
• Optimal Measures for Characterizing Water-rich Super-Earths
• Variability of Brown Dwarfs
• Design Considerations for a Ground-Based Search for Transiting Planets around L and T Dwarfs
• Polarimetric Detection of Exoplanets Transiting T- and L- Brown Dwarfs
• Habitability in Brown Dwarf Systems
• Searching for Exosatellites Orbiting L and T Dwarfs: Connecting Planet Formation to Moon Formation and Finding New Temperate Worlds