15110( 4) - 02-Oct-2017 14:17:48 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15110 Version: 4 Check-in Time: 02-Oct-2017 14:17:48 STScI Edit Number: 0 Title A Study of the UV Environment for Three Small Planets Transiting a Nearby M-Dwarf ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Laura Kreidberg Harvard University Y CoI: Dr. Caroline Morley Harvard University N CoI: Dr. Eliza M.-R. Kempton University of Maryland N CoI: Dr. Leslie Rogers University of Chicago N CoI: Dr. Ian Crossfield Massachusetts Institute of Technology N ------------------------------------------------------------------------------------ Abstract We propose to measure the ultraviolet (UV) spectrum of the M-dwarf K2-3. This nearby system hosts three transiting super-Earths, including one that is a possible candidate to host life. All three planets are excellent targets for atmospheric study, and raise the exciting prospect of comparative planetology with the newly discovered seven planet TRAPPIST-1 system. However, M-dwarfs are bright and active in the UV, which can push their planets' atmospheres out of chemical equilibrium and drive atmospheric mass loss. Some of the most strongly affected molecules, including water, methane, and ozone, are key diagnostics of the planets' formation history, habitability, and even inhabitation. Our measurement of K2-3's UV spectrum will allow us to characterize the impact of photochemistry and mass loss on the planets' atmospheres, thus providing an essential foundation for future investigations of this benchmark system. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will observe the spectrum of the M0-dwarf K2-3 with COS over the wavelength range 1150 - 3200 Angstroms. We will use a combination of the G130M, G160M, and G230L gratings with a range of central-wavelength settings to acquire the complete spectrum. All data will be obtained in TIME-TAG mode so that we can constrain the star's flaring activity. We will use the FLASH=YES setting to maximize exposure time on target. These observations are based on the successful set-up used by the MUSCLES program to measure M-dwarf spectra (GO Programs 12464, 13640). We calculated exposure times needed to achieve a signal-to-noise SNR > 5 for major stellar emission lines in each grating (CII for G130M, C IV for G160M, and Mg II for G230L). We based our calculations on measurements of the spectrum of GJ 832 (an M-dwarf with the closest spectral type to K2-3) from the MUSCLES program (France et al. 2016). To estimate NUV exposure times, we scaled GJ 832 spectrum by K2-3's relative NUV brightness measurements from GALEX (K2-3 is 14x fainter). K2-3 was not detected by GALEX in the FUV band, so for the FUV exposure times, we assumed that K2-3 has the same instrinsic flux as GJ 832 and scaled the expected signal by the distance to the star (K2-3 is 9x more 15110( 4) - 02-Oct-2017 14:17:48 - [ 2] distant than GJ 832, so we expect a roughly 80x smaller signal). The MUSCLES spectrum for GJ 832 has SNR of 75, 40, and 180, for the C IV, CII, and Mg II lines. These data were obtained with exposure times of 15119, 7671, and 2756s using the G160M, G160M, and G230L gratings, respectively. Based on these results and our expectations for the brightness of K2-3, we require 5376, 9600, and 170 s in G130M, G160M, and G230L for a total of 6 orbits accounting for time to acquire the target. There are transiting planets in the system, but the expected signal from the planets is small compared to our photon-noise limited uncertainties. Just to be safe, we include a phase constraint so that the observations do not coincide with the transit of the innermost planet, which is the most likely to have an evaporating exosphere with UV line emission. ------------------------------------------------------------------------------------ 15110( 4) - 02-Oct-2017 14:17:48 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 UCAC4-443-05 STAR, M V-IV RA=11H29M20.3760S +/- 0.5", J2000 V = 12.17 4906 DEC=-01D27'17.33" +/- 0.5" Reference Frame: Other: SIMBAD Extended: NO 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 0.005888564795741611 -0.0736 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 15110( 4) - 02-Oct-2017 14:17:48 - [ 4] Visit: 01 (K2-3 UV spectrum) Visit Requirements: Period 10.05465988 D AND ZERO-PHASE HJD2457627.8435051 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 UCAC4-443-0 COS/NUV ACQ/IMA PSA MIRRORB 1 623.6 S PHASE 0.05 TO 0.9 54906 GE (623.6 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 UCAC4-443-0 COS/NUV TIME-TA PSA G230L 2950 FLASH=YES, FP-POS=ALL, 1 60.0 S 54906 G BUFFER-TIME=1798. (240 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 UCAC4-443-0 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, BUFFER-TIME=5771., 1 706 S (706 54906 G FP-POS=3, SEGMENT=BOTH S) ------------------------------------------------------------------------------------------------------------------------------------ 4 UCAC4-443-0 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, BUFFER-TIME=5771., 1 2915 S 54906 G FP-POS=4, SEGMENT=BOTH (2915 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 UCAC4-443-0 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, BUFFER-TIME=5771., 1 1682 S 54906 G FP-POS=3, SEGMENT=BOTH (1682 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 UCAC4-443-0 COS/FUV TIME-TA PSA G160M 1589 FLASH=YES, BUFFER-TIME=13529., 1 996. S 54906 G FP-POS=1, SEGMENT=BOTH (996 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 UCAC4-443-0 COS/FUV TIME-TA PSA G160M 1589 FLASH=YES, BUFFER-TIME=13529., 1 2915. S 54906 G FP-POS=2, SEGMENT=BOTH (2915 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 UCAC4-443-0 COS/FUV TIME-TA PSA G160M 1589 FLASH=YES, BUFFER-TIME=13529., 1 2915. S 54906 G FP-POS=3, SEGMENT=BOTH (2915 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 UCAC4-443-0 COS/FUV TIME-TA PSA G160M 1589 FLASH=YES, BUFFER-TIME=13529., 1 2915. S 54906 G FP-POS=4, SEGMENT=BOTH (2915 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 | ------------------------------------------------------------------------------------------------------------------------------------ UCAC4-443-054906 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE UCAC4-443-054906 2 COS/NUV TIME-TA PSA G230L 2950 none none none 1 1 N/A G UCAC4-443-054906 2 COS/NUV TIME-TA PSA G230L 2950 none none none 2 1 N/A G UCAC4-443-054906 2 COS/NUV TIME-TA PSA G230L 2950 none none none 3 1 N/A G 15110( 4) - 02-Oct-2017 14:17:48 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ UCAC4-443-054906 2 COS/NUV TIME-TA PSA G230L 2950 none none none 4 1 N/A G UCAC4-443-054906 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G UCAC4-443-054906 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G UCAC4-443-054906 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A G UCAC4-443-054906 6 COS/FUV TIME-TA PSA G160M 1589 none none none none 3 N/A G UCAC4-443-054906 7 COS/FUV TIME-TA PSA G160M 1589 none none none none 4 N/A G UCAC4-443-054906 8 COS/FUV TIME-TA PSA G160M 1589 none none none none 5 N/A G UCAC4-443-054906 9 COS/FUV TIME-TA PSA G160M 1589 none none none none 6 N/A G 15110( 4) - 02-Oct-2017 14:17:48 - [ 6] Summary Form for Proposal 15110 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=13529., BUFFER-TIME=1798., BUFFER-TIME=5771., FLASH=YES, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, FP-POS=ALL, SEGMENT=BOTH ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PHASE 0.05 TO 0.9, Period 10.05465988 D AND ZERO-PHASE HJD2457627.8435051 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M, G230L, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names UCAC4-443-054906 ------------------------------------------------------------------------------------------------------------------------------------