Revisiting the atmosphere of HAT-P-70b with CARMENES high-resolution transmission spectroscopy

TL;DR

This study uses high-resolution transmission spectroscopy to analyze the atmosphere of the ultra-hot Jupiter HAT-P-70b, confirming known features, detecting new signals, and exploring atmospheric winds and composition in the context of similar exoplanets.

Contribution

It provides new high-resolution spectral data on HAT-P-70b, confirming previous atmospheric detections, reporting tentative new detections, and analyzing atmospheric wind and composition in a young UHJ.

Findings

Confirmed Ha, Na I, Ca II detections

Tentative detection of K I and Fe I

Identified blue-shifted atmospheric winds

Abstract

Owing to hot and inflated envelopes that facilitate atmospheric studies, ultra-hot Jupiters (UHJs) have attracted much attention. Significant progress has been achieved, from enlarging the sample size to broadening the studies to encompass diverse stellar types and ages. Here, we present a transmission spectroscopy study of HAT-P-70b, an UHJ orbiting a young A-type star, through high-resolution observations with CARMENES at the 3.5m Calar Alto telescope. By using the line-by-line technique, we confirm the previous detections of Ha, Na I, and Ca II, report a new tentative detection of K I, and impose an upper limit on the He triplet absorption. Through cross-correlation analysis, we identify the Ca II and Fe I absorptions, both blue-shifted by approximately 5 km/s, indicating a day-to-night side atmospheric wind. Additionally, we find a new tentative detection of K I. We do not see any significant atmospheric molecular signal in the near-infrared data. Putting HAT-P-70b in the context of UHJs from the literature, it turns out that (1) Ha absorption is more common on gas giants orbiting stars younger than 1 Gyr, with a relative detection probability of $P_{\rm Age<1\,Gyr}({\rm Ha})/P_{\rm Age\geq1\,Gyr}({\rm Ha})\sim 3$; (2) any UHJ is likely to exhibit Fe I absorption if it has Ca II.