The CRIRES Search for Planets Around the Lowest-Mass Stars. II. The Proposed Giant Planet Orbiting VB10 Does Not Exist

TL;DR

High-precision near-infrared radial velocity measurements of VB10 show no evidence of the proposed giant planet, challenging previous astrometric claims and demonstrating the method's potential for planet detection around low-mass stars.

Contribution

This study provides the first high-precision near-infrared radial velocity data for VB10, refuting earlier planet claims and showcasing the effectiveness of ammonia cell techniques.

Findings

No significant radial velocity variability detected.

Ruled out planets >3 M_Jup with proposed orbit parameters.

Confirmed the non-existence of the claimed giant planet.

Abstract

We present high-precision relative radial velocities of the very low-mass star VB10 that were obtained over a time span of 0.61 yr as part of an ongoing search for planets around stars at the end of the main sequence. The radial velocities were measured from high-resolution near-infrared spectra obtained using the CRIRES instrument on the VLT with an ammonia gas cell. The typical internal precision of the measurements is 10 m/s. These data do not exhibit significant variability and are essentially constant at a level consistent with the measurement uncertainties. Therefore, we do not detect the radial velocity variations of VB10 expected due to the presence of an orbiting giant planet similar to that recently proposed by Pravdo and Shaklan based on apparent astrometric perturbations. In addition, we do not confirm the ~1 km/s radial velocity variability of the star tentatively detected by Zapatero Osorio and colleagues with lower precision measurements. Our measurements rule out planets with M_p > 3 M_Jup and the orbital period and inclination suggested by Pravdo and Shaklan at better than 5 sigma confidence. We conclude that the planet detection claimed by Pravdo and Shaklan is spurious on the basis of this result. Although the outcome of this work is a non-detection, it illustrates the potential of using ammonia cell radial velocities to detect planets around very low-mass stars.