viper: High-precision radial velocities from the optical to the infrared (Reaching 3 m/s in the K band of CRIRES+ with telluric modelling)

Abstract

In recent years, a number of new instruments and data reduction pipelines have been developed to obtain high-precision radial velocities (RVs). In particular in the optical, considerable progress has been made and RV precision below 50 cm/s has been reached. Yet, the RV precision in the near-infrared (NIR) is trailing behind. This is due to a number of factors, such as imprinted atmospheric absorption lines, lower stellar information content, different types of detectors, and usable calibration lamps. However, observations in the NIR are important for the search and study of exoplanets around cool low-mass stars that are faint at optical wavelengths. Not only are M dwarfs brightest in the NIR, the signal of stellar activity is also reduced at longer wavelengths. In this paper we introduce the RV pipeline viper (Velocity and IP EstimatoR). The philosophy of viper is to offer a publicly available and user-friendly code that is able to process data from various spectrographs. Originally designed to handle data from optical instruments, the code now has been extended to enable the processing of NIR data. viper uses a least-square fitting to model the stellar RV as well as the temporal and spatial variable IP. We have improved upon this method by adding a term for the telluric spectrum that enables the forward modelling of molecules present in the Earth's atmosphere. In this paper we use CRIRES+ observations in the K band to demonstrate viper's ability to handle data in the NIR. We show that it is possible to achieve an RV accuracy of 3 m/s over a period of 2.5 years with the use of a gas cell. Additionally, we present a study of the stability of atmospheric lines in the NIR. With viper it is possible to handle data taken with or without a gas cell, and we show that a long-term RV precision of around 10 m/s can be achieved when using only telluric lines for the wavelength calibration.

References in corpus (17)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• ESPRESSO@VLT -- On-sky performance and first results
• Barycentric Corrections at 1 cm/s for precise Doppler velocities
• Bayesian search for low-mass planets around nearby M dwarfs. Estimates for occurrence rate based on global detectability statistics
• Correcting for Telluric Absorption: Methods, Case Studies, and Release of the TelFit Code
• A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs
• CRIRES${}^{+}$ on sky at the ESO Very Large Telescope
• Precision radial velocity measurements by the forward-modeling technique in the near-infrared
• Automatic model-based telluric correction for the ESPRESSO data reduction software. Model description and application to radial velocity computation
• Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs
• Towards a Self-calibrating, Empirical, Light-Weight Model for Tellurics in High-Resolution Spectra
• The cool brown dwarf Gliese 229 B is a close binary
• The CARMENES search for exoplanets around M dwarfs. Telluric absorption corrected high S/N optical and near-infrared template spectra of 382 M dwarf stars
• TOI-2046b, TOI-1181b and TOI-1516b, three new hot Jupiters from \textit{TESS}: planets orbiting a young star, a subgiant and a normal star
• TOI-1268b: the youngest, hot, Saturn-mass transiting exoplanet
• Companions to Kepler giant stars: A long-period eccentric substellar companion to KIC 3526061 and a stellar companion to HD 187878

Cited by in corpus (1)

• PLATOSpec: a precise spectrograph in support of space missions