0 Assigned ID: 561 ----- Attempting Submission 1 (Fri Apr 05 17:26:48 GMT 2019) ----- 0 ----- Attempting Submission 1 (Thu Jul 25 12:08:30 GMT 2019) ----- Far-ultraviolet exploration of nearby young exoplanet-hosting stars One of the proposed explanations for the observed lack of close-in exoplanets with sizes between 1.5 and 2.0 Earth-radii is that this valley is carved by atmospheric erosion: sub-Neptune-sized planets begin their lives with large H/He-rich envelopes, which are lost during their early ages due to photoevaporation. The recent discovery of the young exoplanetary systems in K2-136 and K2-233 provides an excellent opportunity to test this hypothesis using Lyman-alpha transmission spectroscopy, but first we need to evaluate the FUV flux of the stars, which is the main objective of this project. We realistically estimate that the Lyman-alpha emission of these K-type stars are promptly detectable with HST/STIS, despite their distance, owing to their young age. These observations will allow us to study the UV environment and evolution around young low-mass exoplanetary systems, and in the future could lead to the first evidence of atmospheric escape in a young sub- Neptune. This program aims to observe the Lyman-alpha emission (1215 A) of young planet-hosting K4-type stars (V mag ~ 11) using the FUV-MAMA detector and the G140M grating centered in 1222 A. We perform the ACQ/PEAK exposures in spectroscopic mode because the target stars are too bright in the visible to be observed with MIRROR + 52X0.05D1 aperture (the same as the science exposures). We moved the AUTO-WAVECAL to GO-WAVECAL during Earth occultation: the time gained for the scientific exposures would be very useful, since the stars are faint in the FUV. The Bright Object Tool says all targets in the field are safe, however there is one unknown in the field of K2-136 in the GSC II database. Since our program has only 2 orbits and we do not have strict time-window limits, the eventual failure of one of the gyros does not have a significant impact on our program and it can still be carried on whenever a feasible time window is available. Prof. David Ehrenreich, Dr. Vincent Bourrier and Dr. Baptiste Lavie have an extensive experience on UV data analysis of planet-hosting stars, space- and ground-based transmission spectra and have several publications on ground-breaking discoveries about exoplanetary atmospheres. Moreover, Dr. Bourrier developed empirical and analytical tools to analyze and interpret observations of atmospheric escape from exoplanets. Mr. Leonardo dos Santos is an expert spectroscopist with experience on data reduction and analysis of IR, optical and FUV stellar spectra, as well as the development of new methods to interpret stellar spectra; L. dos Santos is leading studies in the rotational and activity evolution of solar-type stars, as well as transmission spectra of exoplanets around M dwarfs using HST data. Planets and Planet Formation Stellar Physics 6 false false true false false false false SUPPORTED STAR EXTRA-SOLAR PLANETARY SYSTEM K III-I Astrometric information obtained from Gaia and magnitudes from SIMBAD. J2000 J2000 B 11.81, G 10.4191, J 8.968, H 8.501, K 8.375 STAR EXTRA-SOLAR PLANETARY SYSTEM K V-IV Astrometric information obtained from Gaia and magnitudes from SIMBAD. J2000 J2000 B 12.48, R 10.90, G 10.8545, J 9.096, H 8.496, K 8.368 STIS/FUV-MAMA Spectroscopic No No G140M 1218 STIS/FUV-MAMA Spectroscopic No No G140M 1218 /Users/leonardo/OneDrive - unige.ch/Research/Exoplanets/Proposals/HST/Young-planets-cycle27/phase_2/OP-cache/young_stars_phaseII-v01.xml The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15934 :visit-id "01" :proposal-version -1 :trans-version "20190514" :date "23-Jul-2019 13:21:39.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 157536 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15934 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15934 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2764 :al-overhead-at-end 0 :internal-dur-at-end 639 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 1 0 The target is too bright for the longpass filter, so the F28X50OII was selected instead. The time to reach signal to noise ratio of 40 is estimated at 6 s, with time to saturation 603 s. We need to use a grating instead of mirror because the target is too bright. 12 s allows to reach S/N=10 with STIS/CCD/G430M and aperture 52x0.05D1 (the same as the science observations), and is below the time to saturation (4000 s). The Spectroscopic ETC yields a warning about the issue with charge transfer efficiency for low background, but we are just using the CCD for the target acquisition, after which we switch to the MAMA. We are photon-starved and set the exposure time to the maximum possible value. The star is later-type (K3) than the K0 stars HD189733 and HD97658, observed with the same settings in previous programs, and it is farther away and fainter. We thus expect lower count rates, and set the buffer-time as Texp/2. /Users/leonardo/OneDrive - unige.ch/Research/Exoplanets/Proposals/HST/Young-planets-cycle27/phase_2/OP-cache/young_stars_phaseII-v02.xml The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15934 :visit-id "02" :proposal-version -1 :trans-version "20190514" :date "23-Jul-2019 13:21:40.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 157536 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15934 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15934 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2764 :al-overhead-at-end 0 :internal-dur-at-end 639 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 1 0 The target is too bright for the longpass filter, so the F28X50OII was selected instead. The time to reach signal to noise ratio of 40 is estimated at 13 s, with time to saturation 1286 s. We need to use a grating instead of mirror because the target is too bright. 19 s allows to reach over S/N=10 with STIS/CCD/G430M and aperture 52x0.05D1 (the same as the science observations), and is below the time to saturation (5800 s). The Spectroscopic ETC yields a warning about the issue with charge transfer efficiency for low background, but we are just using the CCD for the target acquisition, after which we switch to the MAMA. We are photon-starved and set the exposure time to the maximum possible value. The star is later-type (K6) than the K0 stars HD189733 and HD97658, observed with the same settings in previous programs, and it is farther away and fainter. We thus expect lower count rates, and set the buffer-time as Texp/2.