14782( 3) - 12-Dec-2016 19:53:03 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14782 Version: 3 Check-in Time: 12-Dec-2016 19:53:03 STScI Edit Number: 1 Title Is the atmosphere of the extremely irradiated exoplanet WASP-43b in a blow-off state? ------------------------------------------------------------------------------------ Type Cycle GO 24 ------------------------------------------------------------------------------------ Investigators Contact? PI: Mr. Lorenzo Pino Universita degli Studi di Padova Y CoI: Dr. David Ehrenreich Observatoire de Geneve N CoI: Dr. Vincent Bourrier Observatoire de Geneve N CoI: Mr. Aurelien Wyttenbach Observatoire de Geneve N CoI: Dr. Christophe Lovis Observatoire de Geneve N CoI: Prof. Giampaolo Piotto Universita degli Studi di Padova N CoI: Dr. Valerio Nascimbeni Universita degli Studi di Padova N CoI: Dr. Francesco Pepe Observatoire de Geneve N ------------------------------------------------------------------------------------ Abstract In the past months we have obtained evidence that an unusual phenomenon is happening in the atmosphere of one of the Hot Jupiters with shortest period. High-resolution spectroscopy from the ground reveals a transit spectrum where the sodium absorption signal from the planet peaks at 2-3%, which is larger than the planet transit depth in white light and 100 times larger than the well HST-established detection of sodium in HD 209458b (Charbonneau et al. 2002). Only in the UV have such large signatures been observed, for lighter hydrogen, carbon and oxygen atoms being blown-off by hydrodynamical atmospheric escape. So far, sodium atoms have never been observed higher than the thermosphere, where they should get promptly ionized. Analysis of ground-based data is challenging because the spectroscopic signatures can be mimicked by the Earth atmosphere, and a sophisticated removal of telluric contamination is necessary. Our observations show that an efficient telluric correction for this target, particularly faint in the sodium region, is impossible, making a space-based confirmation necessary. In a single transit, HST/STIS could obtain a 5-sigma confirmation of the signal. This detection would unambiguously show that the planetary atmosphere is in a state of extreme blow-off, with large exospheric densities allowing for a high recombination rate able to maintain sodium in a neutral state even high up in the atmosphere. This would represent the first constraint on atmospheric evaporation obtained in the optical, and would thus open a new, UV-independent path to the characterization of evaporating atmospheres, crucial in the post-HST era. ------------------------------------------------------------------------------------ Observations Description ------------------------ We are going to collect STIS spectra during one transit of WASP-43b. In order to have enough out-of-transit and in-transit data 4 orbits are required. Two orbits will be collected before the transit of the planet to establish the baseline flux, one during and one after the transit. This strategy allows to measure the drop in stellar flux due to the transit of the planet. Key to the success of the program is extremely precise photometry, of which HST/STIS has already demonstrated to be capable. 14782( 3) - 12-Dec-2016 19:53:03 - [ 2] We are going to use the STIS CCD G750M observing mode centred at 6094 A to observe sodium at R ~ 5000, and with the 52'' x 2'' slit to minimize flux losses. The duration of the transit is of 2200 s excluding ingress and egress, thus it is possible to completely cover it with the third orbit. Each orbit is split in ~ 270 s exposures with sub-array reading (efficiency > 90 %), to sample the transit of the planet finely enough while keeping a high duty cycle. Additional comments: Experience gained from past proposals by several groups (14461, 14410, 12473, 11572 among others) has shown that maximized photometric precision and efficient thermal breathing trends removal is key to the success of HST transit observations. This is achieved with three main precautions: - We set WAVECAL=NO for the visit and perform manual wavelength calibrations during Earth occultation to acquire a consevutive time series in each orbit. - A short exposure (1 sec) is performed before the scientific time series, following the method indicated in Sing et al., 2015, MNRAS, 446, 2428. This is to minimize the impact of possible systematics in the first exposure. - Again following past proposals, we set the other STIS settings in order to maximize counts and reduce readout time overheads: CR-SPLIT=NO, GAIN=4, SIZEAXIS2=128. ------------------------------------------------------------------------------------ 14782( 3) - 12-Dec-2016 19:53:03 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GSC-05490-00 STAR, EXTRA-SOLAR RA=10H19M38.0080S, J2000 V = -3.6 V = 12.5 +/- 0.1 APASS r = 11.9 141 PLANET, K V-IV DEC=-09D48'22.59" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 -0.0029227028771761847 -0.0432 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14782( 3) - 12-Dec-2016 19:53:03 - [ 4] Visit: 01 (First visit) Visit Requirements: Period 0.813473978 D AND ZERO-PHASE HJD2455528.868634 On Hold Comments: Additional Comments: For this proposal it is necessary to have a visit of four orbits in a continuous block, because the transit of the planet has to be fully sampled. 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 GSC-05490-0 STIS/CCD ACQ F28X50LP MIRROR 1 1 S (1 S) PHASE 0.8058 TO 0.8161; 0141 GS ACQ SCENARIO BASE1B3 ------------------------------------------------------------------------------------------------------------------------------------ 2 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, GAIN=4, 1 1 S (1 S) 0141 SIZEAXIS2=128, WAVECAL=NO Comments: Short exposure to minimize instrument systematic of first exposure in each orbit (e.g. HST proposal 12473). ------------------------------------------------------------------------------------------------------------------------------------ 3 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, SIZEAXIS2=128, 8 279 S 0141 GAIN=4, WAVECAL=NO (2232 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WAVE STIS/CCD ACCUM 52X0.2 G750M 6094 1 DEF (0 S) Comments: Explicit WAVECAL, auto-wave disabled ------------------------------------------------------------------------------------------------------------------------------------ 5 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, GAIN=4, 1 1 S (1 S) 0141 SIZEAXIS2=128, WAVECAL=NO Comments: Short exposure to minimize instrument systematic of first exposure in each orbit (e.g. HST proposal 12473). ------------------------------------------------------------------------------------------------------------------------------------ 6 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, SIZEAXIS2=128, 10 269 S 0141 GAIN=4, WAVECAL=NO (2690 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 WAVE STIS/CCD ACCUM 52X0.2 G750M 6094 1 DEF (0 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, GAIN=4, 1 1 S (1 S) 0141 SIZEAXIS2=128, WAVECAL=NO Comments: Short exposure to minimize instrument systematic of first exposure in each orbit (e.g. HST proposal 12473). ------------------------------------------------------------------------------------------------------------------------------------ 9 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, SIZEAXIS2=128, 10 269 S 0141 GAIN=4, WAVECAL=NO (2690 S) ------------------------------------------------------------------------------------------------------------------------------------ 10 WAVE STIS/CCD ACCUM 52X0.2 G750M 6094 1 DEF (0 S) ------------------------------------------------------------------------------------------------------------------------------------ 14782( 3) - 12-Dec-2016 19:53:03 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, GAIN=4, 1 1 S (1 S) 0141 SIZEAXIS2=128, WAVECAL=NO Comments: Short exposure to minimize instrument systematic of first exposure in each orbit (e.g. HST proposal 12473). ------------------------------------------------------------------------------------------------------------------------------------ 12 GSC-05490-0 STIS/CCD ACCUM 52X2 G750M 6094 CR-SPLIT=NO, SIZEAXIS2=128, 10 269 S 0141 GAIN=4, WAVECAL=NO (2690 S) ------------------------------------------------------------------------------------------------------------------------------------ 13 WAVE STIS/CCD ACCUM 52X0.2 G750M 6094 1 DEF (0 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GSC-05490-00141 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A GSC-05490-00141 2 STIS/CCD ACCUM 52X2 G750M 6094 none none none none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 1 none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 2 none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 3 none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 4 none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 5 none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 6 none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 7 none 1 N/A GSC-05490-00141 3 STIS/CCD ACCUM 52X2 G750M 6094 none none 8 none 1 N/A WAVE 4 STIS/CCD ACCUM 52X0.2 G750M 6094 none none none none 1 N/A GSC-05490-00141 5 STIS/CCD ACCUM 52X2 G750M 6094 none none none none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 1 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 2 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 3 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 4 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 5 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 6 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 7 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 8 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 9 none 2 N/A GSC-05490-00141 6 STIS/CCD ACCUM 52X2 G750M 6094 none none 10 none 2 N/A WAVE 7 STIS/CCD ACCUM 52X0.2 G750M 6094 none none none none 2 N/A GSC-05490-00141 8 STIS/CCD ACCUM 52X2 G750M 6094 none none none none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 1 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 2 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 3 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 4 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 5 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 6 none 3 N/A 14782( 3) - 12-Dec-2016 19:53:03 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 7 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 8 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 9 none 3 N/A GSC-05490-00141 9 STIS/CCD ACCUM 52X2 G750M 6094 none none 10 none 3 N/A WAVE 10 STIS/CCD ACCUM 52X0.2 G750M 6094 none none none none 3 N/A GSC-05490-00141 11 STIS/CCD ACCUM 52X2 G750M 6094 none none none none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 1 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 2 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 3 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 4 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 5 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 6 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 7 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 8 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 9 none 4 N/A GSC-05490-00141 12 STIS/CCD ACCUM 52X2 G750M 6094 none none 10 none 4 N/A WAVE 13 STIS/CCD ACCUM 52X0.2 G750M 6094 none none none none 4 N/A 14782( 3) - 12-Dec-2016 19:53:03 - [ 7] Summary Form for Proposal 14782 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.2, 52X2, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO, GAIN=4, SIZEAXIS2=128, WAVECAL=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, PHASE 0.8058 TO 0.8161, Period 0.813473978 D AND ZERO-PHASE HJD2455528.868634 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G750M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names GSC-05490-00141, WAVE ------------------------------------------------------------------------------------------------------------------------------------