14921( 4) - 23-Jun-2017 13:54:06 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14921 Version: 4 Check-in Time: 23-Jun-2017 13:54:06 STScI Edit Number: 0 Title Atmospheric escape from a mini-Neptune ------------------------------------------------------------------------------------ Type Cycle GO 24 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Monika Lendl Space Research Institute, Austrian Academy Y of Sciences CoI: Prof. David Ehrenreich Observatoire de Geneve N CoI: Dr. Vincent Bourrier Observatoire de Geneve N CoI: Dr. Luca Fossati Space Research Institute, Austrian Academy N of Sciences CoI: Dr. Helmut Lammer Space Research Institute, Austrian Academy N of Sciences CoI: Mr. Baptiste Lavie Observatoire de Geneve N CoI: Dr. Mercedes Lopez-Morales Smithsonian Institution Astrophysical N Observatory CoI: Fatemeh Motalebi Observatoire de Geneve N CoI: Dr. Dimitar D. Sasselov Harvard University N CoI: Dr. Emilio Molinari Telescopio Nazionale Galileo (TNG) N CoI: Dr. Alessandro Sozzetti Osservatorio Astronomico di Torino N CoI: Dr. Lars Buchhave University of Copenhagen, Niels Bohr N Institute ------------------------------------------------------------------------------------ Abstract The transition between rocky and volatile/gas-rich planets is one of the main open questions in exoplanetary research. Population studies show that this transition is not smooth, but rocky super-Earths and gas-rich mini-Neptunes with masses within 7-15 Earth masses should co-exist. Atmospheric escape is surmised to control this transition, causing some planets to lose their atmospheres to space while others retain most of their volatiles and gas. The HD 3167 planetary system, hosting two transiting close-in planets, has been identified from K2 photometry in August 2016. Through a large collaborative effort, we recently pinned down the planetary masses, revealing a duo of super-Earths: one rocky planet (b) and one volatile/gas-rich `mini-Neptune' (planet c). Thanks to its bright host star (V=8.9), this system is poised to become a benchmark target for studies of super-Earth evolution and atmospheres. HD 3167c, in particular, is the mini-Neptune transiting the brightest host star, providing a unique opportunity to access, for the first time, the atmospheric properties of this mysterious class of low-mass, low-density exoplanets. We propose 5 HST orbits to cover one transit of planet c and measure the stellar H I Lyman-alpha emission line. We hope to detect a signature from an extended exosphere escaping the planet. This has never been observed for an exoplanet below 10 Earth masses and would prove that exoplanets in this mass regime can host hydrogen envelopes. A negative result will allow us to assess the far- and extreme-UV environment of both exoplanets, which is critical for planning optimal follow-up strategies. ------------------------------------------------------------------------------------ 14921( 4) - 23-Jun-2017 13:54:06 - [ 2] Observations Description ------------------------ We will observe HD3167 throughout one visit comprised of 5 consecutive HST orbits. The observations target the transit of planet HD3167c in front of its host star. Transits of HD3167c occur every 29.85 days and last 5.15 hours. The visit has been scheduled such that the first two orbits are observed before transit, the third orbit covers transit ingress, and the fourth and fifth orbits are fully observed during transit. This configuration is essential to obtain a solid pre-transit measurement. We have set a phase constraint on the ACQ exposure such that the visit starts between 4.0 and 3.33 hours before transit ingress, and observations end before transit egress. ------------------------------------------------------------------------------------ 14921( 4) - 23-Jun-2017 13:54:06 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-3167 STAR, K V-IV RA=00H34M57.6317S +/- 0.009", J2000 V = V = 8.94 +/- 0.01 B = 9.77 +/- 0.02, R DEC=+04D22'50.68" +/- 0.006" 19.528 = 8.4 +/- 0.02, I = 8.1 +/- 0.02, J = 7.548 +/- 0.03, H = 7.203 +/- 0.04, K = 7.066 +/- 0.02 Reference Frame: ICRS Comments: The coordinates were taken from GAIA DR1. We have verified them against HIPPARCOS coordinates, finding excellent agreement (differences < 0.002 arcsec). Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015 0.007193014542302454 -0.17314 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14921( 4) - 23-Jun-2017 13:54:06 - [ 4] Visit: 01 Visit Requirements: SCHED 100%; Period 29.8454 D AND ZERO-PHASE HJD2457394.9788 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-3167 STIS/CCD ACQ F28X50OII MIRROR 1 5 S (5 S) PHASE 0.990600 TO 0.99325255; SEQ 1-4 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-3167 STIS/CCD ACQ/PEA 52X0.05D1 G430L 4300 1 12 S (12 K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-3167 STIS/FUV TIME-TA 52X0.05D1 G140M 1222 BUFFER-TIME=900, WAVECAL=NO 1 1659 S -MAMA G see below (1593 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WAVE STIS/FUV ACCUM 52X0.05 G140M 1222 1 DEF (0 S) -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 5 HD-3167 STIS/FUV TIME-TA 52X0.05D1 G140M 1222 BUFFER-TIME=900 1 2740 S SEQ 5-6 NON-INT -MAMA G (2740 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 WAVE STIS/FUV ACCUM 52X0.05 G140M 1222 1 DEF (0 S) -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 7 HD-3167 STIS/FUV TIME-TA 52X0.05D1 G140M 1222 BUFFER-TIME=900 1 2740 S SEQ 7-8 NON-INT -MAMA G (2740 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 WAVE STIS/FUV ACCUM 52X0.05 G140M 1222 1 DEF (0 S) -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 9 HD-3167 STIS/FUV TIME-TA 52X0.05D1 G140M 1222 BUFFER-TIME=900 1 2740 S SEQ 9-10 NON-INT -MAMA G (2740 S) ------------------------------------------------------------------------------------------------------------------------------------ 10 WAVE STIS/FUV ACCUM 52X0.05 G140M 1222 1 DEF (0 S) -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 11 HD-3167 STIS/FUV TIME-TA 52X0.05D1 G140M 1222 BUFFER-TIME=900 1 2740 S SEQ 11-12 NON-INT -MAMA G (2740 S) ------------------------------------------------------------------------------------------------------------------------------------ 12 WAVE STIS/FUV ACCUM 52X0.05 G140M 1222 1 DEF (0 S) -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 14921( 4) - 23-Jun-2017 13:54:06 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD-3167 1 STIS/CCD ACQ F28X50OI MIRROR none none none none 1 N/A I HD-3167 2 STIS/CCD ACQ/PEA 52X0.05D G430L 4300 none none none none 1 N/A K 1 HD-3167 3 STIS/FUV TIME-TA 52X0.05D G140M 1222 none none none none 1 1593.0 S -MAMA G 1 WAVE 4 STIS/FUV ACCUM 52X0.05 G140M 1222 none none none none 1 N/A -MAMA HD-3167 5 STIS/FUV TIME-TA 52X0.05D G140M 1222 none none none none 2 N/A -MAMA G 1 WAVE 6 STIS/FUV ACCUM 52X0.05 G140M 1222 none none none none 2 N/A -MAMA HD-3167 7 STIS/FUV TIME-TA 52X0.05D G140M 1222 none none none none 3 N/A -MAMA G 1 WAVE 8 STIS/FUV ACCUM 52X0.05 G140M 1222 none none none none 3 N/A -MAMA HD-3167 9 STIS/FUV TIME-TA 52X0.05D G140M 1222 none none none none 4 N/A -MAMA G 1 WAVE 10 STIS/FUV ACCUM 52X0.05 G140M 1222 none none none none 4 N/A -MAMA HD-3167 11 STIS/FUV TIME-TA 52X0.05D G140M 1222 none none none none 5 N/A -MAMA G 1 WAVE 12 STIS/FUV ACCUM 52X0.05 G140M 1222 none none none none 5 N/A -MAMA 14921( 4) - 23-Jun-2017 13:54:06 - [ 6] Summary Form for Proposal 14921 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.05, 52X0.05D1, F28X50OII ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/PEAK, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=900, WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PHASE 0.990600 TO 0.99325255, Period 29.8454 D AND ZERO-PHASE HJD2457394.9788, SCHED 100%, SEQ 1-4 NON-INT, SEQ 11-12 NON-INT, SEQ 5-6 NON-INT, SEQ 7-8 NON-INT, SEQ 9-10 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140M, G430L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD-3167, WAVE ------------------------------------------------------------------------------------------------------------------------------------