Probing active atmospheric erosion across an adolescent planet system

0 Assigned ID: 4080 ----- Attempting Submission 1 (Tue May 23 08:29:06 GMT 2023) ----- For the best data quality, it is generally required to use all four FP-POS positions at a given COS cenwave (or 2 positions for certain exception cases). See extended explanation in the diagnostic browser. COS EXPOSURE TIME ROUNDED DOWN TO NEAREST 0.1 SECONDS COS EXPOSURE TIME ROUNDED DOWN TO NEAREST 0.1 SECONDS COS EXPOSURE TIME ROUNDED DOWN TO NEAREST 0.1 SECONDS COS EXPOSURE TIME ROUNDED DOWN TO NEAREST 0.1 SECONDS COS EXPOSURE TIME ROUNDED DOWN TO NEAREST 0.1 SECONDS For the best data quality, it is generally required to use all four FP-POS positions at a given COS cenwave (or 2 positions for certain exception cases). See extended explanation in the diagnostic browser. Resubmit 2026-01-26 to remove exposures with FP-POS 2 and 3. Each orbit now contains one science exposure at FP-POS 1. Second resubmission of Phase II to incorporate feedback from ticket INC0206041. Visit 3 and 4 now reconfigured for COS G130M observations, centered at 1327A. Observations are of the stellar Lya line, and we request use of LP3, and both segments for COS. 3 science exposures are requested per orbit, at FP-POS1, 2, and 4. FP-POS3 is avoided due to its lower gain at the Lya line. -2102899596 ----- Attempting Submission 1 (Wed Sep 06 21:15:41 GMT 2023) ----- ----- Attempting Submission 2 (Wed Oct 02 03:45:02 GMT 2024) ----- ----- Attempting Submission 3 (Thu Nov 21 23:04:20 GMT 2024) ----- ----- Attempting Submission 4 (Thu Nov 28 22:35:28 GMT 2024) ----- ----- Attempting Submission 5 (Mon Jan 26 10:44:09 GMT 2026) ----- BOT limit exceeded because it assumes O-type star. Visit planner has been run, and visits are schedule-able based on emails with program coordinators. Accept COS exposure times rounded down. Probing active atmospheric erosion across an adolescent planet system Atmospheric erosion is the universal process that shapes all small planets. We will use STIS to search for the extended neutral hydrogen exosphere around two Neptunes orbiting the 200 million year old star TOI-2076. These observations will reveal active ongoing mass loss from these planets. Detections of Lyman alpha excess around young planets is one of few direct tracers of photoevaporation in real time. We are experimentally testing the factors that influence early atmospheric erosion in young planets by observing a multiplanet system, allowing us to vary the levels of incident XUV irradiation, while holding the stellar XUV evolution history constant. The photoevaporation paradigm is thought to sculpt the entire small planet population we know today, STIS UV observations of young multiplanet systems as TOI-2076 will provide real time tests that anchor this model. Our program will observe transits of TOI-2076b with STIS MAMA-FUV G140M 1222A, and TOI-2076c with COS G130M 1309A to measure the planets' radii in Lyman alpha. We request two visits per planet, each visit will include five consecutive orbits, timed during their respective transits. Our visit timings are requested to allow for 1-2 orbits pre-transit to establish a baseline. Our timing requriement for the first exposure includes a 60 minute window to allow for scheduling flexibility. For visits 1 and 2 with STIS, the first exposure of each visit includes an ACQ and an ACQ/peak exposure. Each orbit include a single science exposure and a wavecal exposure, with the science exposure of the first orbit made shorter to allow for acquisition. For visits 3 and 4 with COS, the first exposure of each orbit includes an ACQ exposure. The science exposures will be performed at Our team includes experts in the discovery, characterization, and modeling of planets around young stars. Dr George Zhou is an expert in searching for and characterising young planetary systems from space and ground based facilities. He runs a search for planets residing around young field stars from TESS. He is the PI of a cycle-30 HST project (GO-17152) to characterise the Lyman-alpha transits of HIP 94235b. Dr Chelsea Huang leads the MIT TESS QLP pipeline, which has resulted in the discovery of thousands of planet candidates from TESS. She is an expert in space-based platforms, and will assist with the analysis of this program. Dr Samuel Quinn is an expert in the search for young planetary systems from TESS. He leads the ground-based spectroscopic follow-up effort for the TESS mission. He led many of the earliest discoveries of planets around young stars in clusters and associations. Allyson Bieryla is an expert in the photometric and spectroscopic followup of planets, working closely with the TESS mission. Dr David Latham is the TESS Director of Science, and has an extensive history of exoplanetary discoveries. Quinn, Bieryla, and Latham will provide simutlaneous ground-based photometric and spectroscopic monitoring of TOI-2076, via institutional access to 1m class telescopes, to map stellar activity simultaneous with HST observations. Ava Morrissey is an expert in the reduction and analysis of HST STIS Lyman alpha observations. She is a PhD student at the University of Southern Queensland, and her thesis explores the observational signatures of atmospheric escape from young planets. Dr Benjamin Pope pioneers new techniques that tackle space-based characterisation of planetary systems, and is part of numerous space-based missions, including NASA Kepler, TESS, and JWST. Prof Duncan Wright is an expert in the follow-up and characterisation of planets, and is a member of the exoplanet atmospheres mission Twinkle. Exoplanets and Exoplanet Formation 6 false false false false false false false AVAILABLE STAR EXTRA-SOLAR PLANET EXTRA-SOLAR PLANETARY SYSTEM G V-IV NO TOI-2076 J2000 J2000 STIS/FUV-MAMA Spectroscopic No No G140M 1222 STIS/FUV-MAMA Spectroscopic No No G140M 1222 STIS/FUV-MAMA Spectroscopic No No G140M 1222 STIS/FUV-MAMA Spectroscopic No No G140M 1222 1732229734932 The scheduling data was generated by CASM 32.1.3. 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