Radial velocity precision of ESPRESSO through the analysis of the solar twin HIP 11915

TL;DR

This study evaluates ESPRESSO's radial velocity precision using 24 observations of the solar twin HIP 11915, achieving a residual RMS scatter of about 20 cm/s, highlighting its potential for detecting Earth-like exoplanets.

Contribution

First application of ESPRESSO data to a solar twin demonstrating near 20 cm/s RV precision using Gaussian Process modeling.

Findings

RV residual RMS scatter of ~20 cm/s for HIP 11915

ESPRESSO's performance approaches the 10 cm/s goal

Stellar activity impacts can be mitigated with advanced methods

Abstract

Different stellar phenomena affect radial velocities (RVs), causing variations large enough to make it difficult to identify planet signals from the stellar variability. RV variations caused by stellar oscillations and granulation can be reduced through some methods, but the impact of rotationally modulated magnetic activity on RV, due to stellar active regions is harder to correct. New instrumentation promises an improvement in precision of one order of magnitude, from about 1 m/s, to about 10 cm/s. In this context, we report our first results from 24 spectroscopic ESPRESSO/VLT observations of the solar twin star HIP 11915, spread over 60 nights. We used a Gaussian Process approach and found for HIP 11915 a RV residual RMS scatter of about 20 cm s$^{-1}$, representing an upper limit for the performance of ESPRESSO.