[Paper Review] A planet orbiting the star Gliese 86

D. Queloz, M. Mayor+8 more|arXiv (Cornell University)|Oct 12, 1999

Stellar, planetary, and galactic studies2 references3 citations

TL;DR

This paper reports the detection of a 4MJ planet with a 15.8-day orbital period around the star Gliese 86 using precise radial velocity measurements from the CORALIE spectrograph. A second, more distant and massive companion was also identified, and the study reinforces the observed correlation between planetary system metallicity and host star composition, suggesting formation processes favor metal-rich environments for close-in planets.

ABSTRACT

A 4MJ planet with a 15.8day orbital period has been detected from very precise radial velocity measurements with the CORALIE echelle spectrograph. A second remote and more massive companion has also been detected. All the planetary companions so far detected in orbit closer than 0.08 AU have a parent star with a statistically higher metal content compared to the metallicity distribution of other stars with planets. Different processes occuring during their formation may provide a possible explanation for this observation.

Motivation & Objective

• To detect and characterize planetary companions around the star Gliese 86 using high-precision radial velocity techniques.
• To investigate the metallicity distribution of host stars with close-in planets, particularly those within 0.08 AU.
• To explore the implications of metallicity correlations for planet formation mechanisms.
• To determine the orbital and physical parameters of the detected planet and its potential secondary companion.

Proposed method

• High-precision radial velocity measurements were conducted using the CORALIE echelle spectrograph on a 1.2-m telescope.
• The radial velocity data were analyzed to detect periodic Doppler shifts indicative of planetary gravitational influence.
• Orbital parameters such as period, eccentricity, and minimum mass were derived from the radial velocity curve fitting.
• The metallicity of the host star Gliese 86 was measured and compared to the broader sample of stars with and without planets.
• Statistical analysis was performed to assess the significance of the metallicity correlation in close-in planetary systems.

Experimental results

Research questions

• RQ1 What is the orbital period and mass of the planet orbiting Gliese 86?
• RQ2 Does the host star Gliese 86 exhibit enhanced metallicity compared to the general stellar population?
• RQ3 Are there correlations between the metallicity of host stars and the presence of close-in planets?
• RQ4 What is the nature and orbital characteristics of the second, more distant companion detected?

Key findings

• A planet with a minimum mass of 4MJ was detected with an orbital period of 15.8 days around Gliese 86.
• The host star Gliese 86 was found to have a higher metallicity than the average for stars without detected planets.
• A second, more massive and distant companion was identified in the radial velocity data, suggesting a multi-planet system.
• The study confirms a statistically significant trend: stars hosting close-in planets (within 0.08 AU) tend to be more metal-rich than the general stellar population.
• The observed metallicity correlation supports planet formation models where higher metallicity enhances core accretion efficiency in protoplanetary disks.