First light and results for atmospheric characterization with The Near Infra-Red Planet Searcher (NIRPS)

Allart, Romain; Pelletier, Stefan; Lim, Olivia; Piaulet, Caroline; Mounzer, Dany; Bourrier, Vincent; Costa Silva, Ana Rita; Vandal, Thomas; Carteret, Yann; Artigau, Etienne; Bouchy, François; Doyon, Rene; Nirps Consortium
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AAS/Division for Extreme Solar Systems Abstracts

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NIRPS is a new fiber-fed high spectral resolution (~80k) spectrograph assisted by adaptive optics installed on the 3.6m telescope of ESO at LaSilla, Chile. Operated simultaneously with HARPS, NIRPS covers the Y, J, and H bands. The commissioning phase demonstrated high stability for time-series observations along precise radial velocities reaching the 1 m/s level. In this talk, I will describe the objectives of the NIRPS consortium that has been allocated 725 nights of Guaranteed Time Observations (GTO) in the next 5 years. A third of this time is dedicated to in-depth spectral characterizations to provide detailed high-fidelity high signal-to-noise transmission and emission spectra as well as large comprehensive atmospheric and orbital architecture surveys that will be done for more than 75 exoplanets from ultra-hot Jupiters to temperate terrestrial planets. Over the first two years of the program, we are prioritizing the best exoplanets, which include many JWST targets. It will provide a unique opportunity to combine low- and high-resolution datasets to unlock the complete picture of exoplanets atmospheres. I will present the first results that have been obtained since the start of operation on April 1st including the detections of escaping atmospheres along with the presence of molecules and atoms in the atmospheres of warm Neptunes to hot Jupiters. A special focus of this talk will be on the analysis of WASP-69b for which I will present observations of the Rossiter-McLaughlin effect and the metastable helium triplet. We confirm the aligned orbit of WASP-69b and show good agreement in precision between NIRPS and simultaneous HARPS observations. We confirm the strong helium absorption signature observed over three independent visits. The helium light curve shows post-transit absorption, suggesting the presence of a cometary tail formed by the escaping atmosphere. In addition, we put in evidence an increasing blueshift of the signature from the ingress to the post-transit absorption. Finally, we use the derived orbital architecture properties to interpret the helium transmission spectra with a self-consistent model of the star and planet. To do so, we perform three-dimensional simulations of the transit with the EVE code, considering the geometry of the transit and the effects induced by the occultation of the stellar surface, providing constraints on the atmospheric structure and dynamic of the upper atmosphere along mass loss rate. This result showcases the potential of NIRPS to deliver high-fidelity atmospheric spectra to constrain the formation and evolution of exoplanets at the statistical level.