[Paper Review] The CORALIE survey for southern extrasolar planets V: 3 new extrasolar planets

D. Naef, M. Mayor+5 more|ArXiv.org|Jun 14, 2001

Stellar, planetary, and galactic studies30 references54 citations

TL;DR

This paper reports the detection of three new extrasolar planets via radial-velocity measurements using the CORALIE spectrograph on the 1.2-m Leonhard Euler Telescope at La Silla Observatory. The planets orbit GJ 3021, HD 52265, and HD 169830 with orbital periods of 133.7, 119.2, and 229.9 days, respectively, all exhibiting significant eccentricities (0.51, 0.35, 0.35) and minimum masses between 1.05 and 3.37 M_Jup, confirming their Jovian nature and metal-rich host stars.

ABSTRACT

We report the detection of 3 new planetary companions orbiting the solar-type stars GJ 3021, HD 52265 and HD 169830 using radial-velocity measurements taken with the CORALIE echelle spectrograph. All these planetary companions have longer orbital periods than the 51 Peg-like objects. The orbits are fairly eccentric. The minimum masses of these planets range from 1 to 3.3 M_Jup. The stars have spectral types from F8V to G6V. They are metal-rich. We also present our radial-velocity measurements for three solar-type stars known to host planetary companions iota Hor (HD 17051), HD 210277 and HD 217107.

Motivation & Objective

• To detect and characterize low-mass planetary companions around solar-type stars using high-precision radial-velocity measurements.
• To investigate the orbital properties, masses, and eccentricities of newly discovered planetary systems in the southern sky.
• To assess the chromospheric activity and lithium abundance of host stars to evaluate stellar activity effects on radial-velocity signals.
• To confirm and refine orbital solutions using combined data from multiple observatories, improving precision on orbital elements.
• To explore the metallicity and kinematic properties of host stars to assess their potential membership in stellar moving groups.

Proposed method

• Radial-velocity measurements were obtained using the CORALIE echelle spectrograph with a precision of ~7–8 m s⁻¹, employing the simultaneous thorium-argon referencing technique to correct for instrumental drifts.
• The cross-correlation function (CCF) between stellar spectra and a numerical template was used to derive radial velocities, with systematic offsets corrected using overlapping data from other surveys.
• Orbital solutions were fitted using Keplerian models, with eccentricity and systemic velocity (γ) as free parameters, and χ² statistics used to assess model significance.
• A quadratic trend in the residuals was fitted to account for non-linear systemic velocity drifts, particularly in the HD 52265 system, to improve orbital fit quality.
• Stellar parameters including effective temperature, luminosity, metallicity, and lithium abundance were derived from spectroscopic analysis of CORALIE data.
• Kinematic properties (U, V, W velocities) were computed from Hipparcos astrometry and radial velocities to assess membership in stellar moving groups such as the Hyades Super-Cluster.

Experimental results

Research questions

• RQ1 Do the radial-velocity variations in GJ 3021, HD 52265, and HD 169830 indicate the presence of planetary companions with long orbital periods and high eccentricities?
• RQ2 What is the minimum mass and orbital configuration of the detected companions, and how do they compare to known Hot Jupiters?
• RQ3 To what extent does stellar activity—measured via chromospheric activity and lithium abundance—contribute to radial-velocity noise in these systems?
• RQ4 Is the observed systemic velocity drift in HD 52265 consistent with a linear trend, or does it require a quadratic correction?
• RQ5 Are the host stars metal-rich, and do their kinematic and spectroscopic properties suggest membership in the Hyades Super-Cluster?

Key findings

• Three new extrasolar planets were detected: GJ 3021 b (P = 133.7 d, e = 0.51, m sin i = 3.37 M_Jup), HD 52265 b (P = 119.2 d, e = 0.35, m sin i = 1.05 M_Jup), and HD 169830 b (P = 229.9 d, e = 0.35, m sin i = 2.94 M_Jup).
• The orbital solutions for all three planets show significant eccentricity, with the Lucy & Sweeney test confirming non-zero eccentricity at nearly 100% confidence level.
• GJ 3021 exhibits high chromospheric activity (log R'_{HK} = -4.77), which contributes to velocity residuals and may affect orbital solution precision.
• Lithium abundance analysis revealed strong Li I λ6707.8 Å absorption in GJ 3021 and HD 52265, but no detectable lithium in HD 169830, consistent with age and activity trends.
• All three host stars are metal-rich (Fe/H > 0), with GJ 3021’s kinematics (U, V, W = 33.7, -17.4, 2.8 km s⁻¹) matching those of the Hyades Super-Cluster.
• A quadratic velocity drift was detected in the HD 52265 system (second-order term: -2.83 ± 0.54 × 10⁻⁴ m s⁻¹ d⁻²), indicating a non-linear systemic velocity trend over the observation baseline.