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Updated: Jul 28, 2026
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Bringing the Visible Universe into Focus with Robo-AO
Published on: February 12, 2013
The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458.
The Astrophysical Journal
|March 4, 2000
Summary
We determined the orbit of a transiting exoplanet around the star HD 209458. This gas giant planet has a mass of 0.69 Jupiter masses and a radius of 1.40 Jupiter radii.
Area of Science:
- Exoplanetary science
- Stellar astrophysics
- Planetary dynamics
Background:
- The study of exoplanets provides insights into planetary formation and evolution.
- HD 209458 is a solar-type star known to host a transiting exoplanet, making it a key target for detailed characterization.
Purpose of the Study:
- To precisely determine the orbital parameters and physical properties of the exoplanet companion to HD 209458.
- To refine stellar parameters for HD 209458 through detailed spectral analysis and comparison with stellar evolution models.
Main Methods:
- Spectroscopic analysis of the host star HD 209458 to determine its metallicity, mass, and radius.
- Re-analysis of transit data using refined stellar parameters to derive the planet's orbital inclination.
- Calculation of the exoplanet's mass, radius, and density.
Main Results:
- A spectroscopic orbit with a period of 3.52433 days was determined for the exoplanet.
- The host star HD 209458 has a mass of 1.1 solar masses and a radius of 1.2 solar radii.
- The exoplanet has a mass of 0.69 Jupiter masses, a radius of 1.40 Jupiter radii, and a density of 0.31 g cm⁻³.
Conclusions:
- The derived physical and orbital parameters provide a comprehensive characterization of the HD 209458 system.
- The planet's low density suggests a likely composition as a gas giant.
- This study refines our understanding of exoplanet properties and their host stars.
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