I Simposio de Postgrado 2023. Ingeniería, ciencias e innovación

MÓDULO_ 01 Astronomía y Física 34 A SEARCH FOR ATOMIC ELEMENTS IN THE ATMOSPHERE OF LTT 9779B USING ESPRESSO ABSTRACT Context. LTT 9779 b is an ultra-hot Neptune that was recently discovered using the Transiting Exoplanet Survey Satellite TESS.The planet has a short orbital period of only 19 hours and an equilibrium temperature of ~2000 K, and therefore lies in the middle of the Neptune Desert. However, even after two billion years of evolution embedded within the intense radiation field of the host star, it still maintains an atmospheric mass fraction of ~ 10%. Aims. Using high signal-to-noise ratio and high spectroscopy from Echelle Spectrograph for Rocky Exoplanet and Stable Spectro- scopic Observations, ESPRESSO, we aim to search for atomic and molecular species in LTT 9779 b ’s atmosphere. Methods. We performed transmission spectroscopy through both single-line absorption and the cross-correlation techniques to detect the atmospheric signals from Na, K, Hα, Ca, Fe, TiO, and V. We also model the Rossiter-McLaughlin effect and the center to limb variations to help identify any false positive signals. Results. With the current datasets from ESPRESSO, we do not detect the presence of any of the aforementioned elements, from neither of the methods we applied. We were able to determine a 500 ppm upper limit for the transmission signal detections of each of the elements, allowing us to rule out various models. Conclusions. We interpret the lack of any detection as evidence of a very high metallicity for the planet’s atmosphere, since this would give rise to a high mean molecular weight (μatm ≥ 4) and hence a low atmospheric scale height, rendering any signal too weak to be detected. Another possibility is the presence of high altitude cloudsorhazeswhichwill suppressanysignal fromelementsdeeper intheatmosphere. Future observations frominstruments onboard JWST for example,will help to provide amore detailed understanding of the planet’s atmospheric properties. 1 Departamento de Astronomía, Universidad de Chile. 2 Núcleo de Astronomía , Universidad Diego Portales. 3 Centro de Astrofísica y Tecnología Afinas (CATA). 4 Europena Southern Observatory (ESO). *Email: rramirez@das.uchile.cl R. Ramirez Reyez 1,3* , James S. Jenkins 2,3 , J. V. Seidel 4