How to Weigh a Star Using a Moon

Abstract

We show that for a transiting exoplanet accompanied by a moon which also transits, the absolute masses and radii of the star, planet and moon are determinable. For a planet-star system, it is well known that the density of the star is calculable from the lightcurve by manipulation of Kepler's Third Law. In an analogous way, the planetary density is calculable for a planet-moon system which transits a star, and thus the ratio-of-densities is known. By combining this ratio with the observed ratio-of-radii and the radial velocity measurements of the system, we show that the absolute dimensions of the star and planet are determinable. This means such systems could be used as calibrators of stellar evolution. The detection of dynamical effects, such as transit timing variations, allows the absolute mass of the moon to be determined as well, which may be combined with the radius to infer the satellite's composition.

5 pages; Accepted in MNRAS

References in corpus (9)

• The orbital motion, absolute mass, and high-altitude winds of exoplanet HD209458b
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• Detailed Models of super-Earths: How well can we infer bulk properties?
• Transit timing effects due to an exomoon
• Analytic Approximations for Transit Light Curve Observables, Uncertainties, and Covariances
• Determination of the size, mass, and density of "exomoons" from photometric transit timing variations
• The fate of moons of close-in giant exoplanets
• Direct Measurement of the Radius and Density of the Transiting Exoplanet HD 189733B with the CHARA Array
• On the Possibility of Tidal Formation of Binary Planets Around Ordinary Stars

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• Exomoon habitability constrained by illumination and tidal heating
• Formation, Habitability, and Detection of Extrasolar Moons
• The Hunt for Exomoons with Kepler (HEK): II. Analysis of Seven Viable Satellite-Hosting Planet Candidates
• The Hunt for Exomoons with Kepler (HEK): V. A Survey of 41 Planetary Candidates for Exomoons
• An Exomoon Survey of 70 Cool Giant Exoplanets and the New Candidate Kepler-1708 b-i
• On the detection of Exomoons: A search in Kepler data for the orbital sampling effect and the scatter peak
• How to determine an exomoon's sense of orbital motion
• LUNA: An algorithm for generating dynamic planet-moon transits
• Measuring the Galactic Distribution of Transiting Planets with WFIRST
• Quantifying the challenges of detecting unseen planetary companions with transit timing variations
• Discovery of a Transiting Planet Near the Snow-Line
• Model-Independent Stellar and Planetary Masses from Multi-Transiting Exoplanetary Systems
• The Possible Moon of Kepler-90g is a False Positive
• A full transit of ${\nu }^2$ Lupi d and the search for an exomoon in its Hill sphere with CHEOPS
• Traces of exomoons in computed flux and polarization phase curves of starlight reflected by exoplanets
• Astrometric exomoon detection by means of optical interferometry
• The Transits of Extrasolar Planets with Moons