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A High-Eccentricity Low-Mass Companion to HD 89744
The Astrophysical Journal
|April 19, 2000
Summary
Astronomers discovered a low-mass companion orbiting the star HD 89744 using radial velocity data. This extrasolar planet exhibits a highly eccentric orbit, reinforcing known trends in exoplanet research.
Area of Science:
- Astronomy
- Astrophysics
- Exoplanet Research
Background:
- HD 89744 is an F7 V star with characteristics including a mass of 1.4 M☉, temperature of 6166 K, age of 2.0 Gyr, and metallicity [Fe/H]=0.18.
- Radial velocity monitoring of HD 89744 began in 1996, indicating the presence of a low-mass companion.
Purpose of the Study:
- To confirm and characterize a low-mass companion orbiting the star HD 89744.
- To determine the orbital parameters and minimum mass of the companion.
Main Methods:
- Utilized the Advanced Fiber-Optic Echelle spectrograph at Whipple Observatory for radial velocity monitoring.
- Incorporated supplementary data from the Hamilton spectrograph at Lick Observatory during the companion's periastron passage.
Main Results:
- Determined the orbital period (P) to be 256 days and the orbital amplitude (K) to be 257 m/s.
- Calculated an orbital eccentricity (e) of 0.7, one of the highest known for extrasolar planets.
- Inferred a minimum companion mass (m2sini) of 7.2 MJupiter in a semimajor axis orbit (a2) of 0.88 AU.
Conclusions:
- The high eccentricity of the HD 89744 companion aligns with the trend of increased eccentricity for exoplanets with semimajor axes greater than 0.15 AU.
- The high metallicity of the host star supports the correlation between high stellar metallicity and the presence of extrasolar planets.