16048( 4) - 31-Jan-2020 16:22:56 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16048 Version: 4 Check-in Time: 31-Jan-2020 16:22:56 STScI Edit Number: 1 Title Extremely Metal Poor Galaxies: Understanding the Boundaries of Galaxy Evoution ------------------------------------------------------------------------------------ Type Cycle GO 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Kristen B W McQuinn Rutgers the State University of New Jersey Y CoI: Dr. Danielle Berg The Ohio State University N CoI: Dr. Grace Telford Rutgers University N CoI: Dr. Andrew Eugene Dolphin Raytheon Company N ------------------------------------------------------------------------------------ Abstract After decades of fruitless searches, we are finally starting to find star-foming galaxies with exceptionally low gas-phase oxygen abundances in the nearby universe. Such galaxies have properties at the limit of what we expect from galaxy evoution models, providing unique boundary conditions for low-mass galaxies in the present-day universe. Termed 'extremely metal-poor' or XMP galaxies, with abundances <5% solar, these galaxies nearly ubiquitously disagree with expectations of the well-established luminosity-metallicity relation (LZR) of dwarf galaxies. There are two exceptions. The first is the nearby galaxy Leo P (D=1.6 Mpc), whose low abundance is consistent with inefficient star formation and metal-loss via galactic winds. The second is the newly discovered XMP galaxy J1005+3722. Tantalizingly close at 2.7 Mpc, the galaxy has a robust, direct-method oxygen abundance of 12+log(O/H) = 7.25 and, similar to Leo P, is consistent with the LZR. We request HST ACS imaging of the stellar populations in J1005+3722 to derive the star formation and chemical enrichment history of the galaxy and determine whether (i) the galaxy has experienced constant or delayed star formation, and (ii) the low oxygen abundance is consistent with expectations from secular processes (i.e., low star formation rates and metal expulsion). J1005+3722 is in the expected abundance regime of galaxies at high-redshift that will be identified by JWST, but forever out-of-reach for detailed study. It is through the analysis possible on galaxies like J1005+3722 in the local universe, where the observations are best, that we build our foundational knowledge of metal-poor galaxies and help prepare for JWST. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of this proposal is to measure the distance, search for variable stars, and reconstruct and interpret the star formation history (SFH) and chemical enrichment history of the newly discovered XMP dwarf galaxy J1005+3722 from a deep color-magnitude diagram (CMD). Orbit allocation = 13 orbits. Most visits span 2-orbits with the ACS with the final vist spanning 3-orbits; each orbit is split between one F606W and one F814W exposure (with no CR-splits). Small ditherings are performed between exposures in order to remove hot pixels and to smooth the detector response. We don't intend to cover the interchip gap. Ditherings are performed using POS-TARG, and following the basic 16048( 4) - 31-Jan-2020 16:22:56 - [ 2] UDF dither pattern, shifted around by 2-3 pix. The observations will complete a total of 4 uniquely positioned UDF dither patterns plus an additional set of F606W and F814W images with a POS-TARG offset of 0.05, 0.05. The first visit is requested within a given range of orientations. This range has been chosen to minimize the impact of a bright foreground star on the photometry of the galaxy and to ensure the galaxy is not impacted by the chip gap. Subsequent visits are requested to be obtained with the same ORIENT as the first visit in order to maximize the sky area covered at full depth. We request the visits to be executed sequentially within a maximum time span of 3 days, ideally avoiding 12 hour intervals in the observations as this matches the cadence of the expected variable star light curves. The request sequence of data will ensure optimal sampling of the light curves of short period variable stars such as RR Lyrae, which will provide an independent constraint on the SFH of the galaxy, the main science goal of our progam. ------------------------------------------------------------------------------------ 16048( 4) - 31-Jan-2020 16:22:56 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 J1005+3722 GALAXY, AMORPHOUS RA=10H05M13.5500S, J2000 V = 19 IRREGULAR, STAR FORMING DEC=+37D22'53.15" REGION Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 16048( 4) - 31-Jan-2020 16:22:56 - [ 4] Visit: 01 (Visit 01) Visit Requirements: ORIENT 358D TO 60 D; ORIENT 177D TO 235 D; ORIENT 315D TO 320 D; ORIENT 145D TO 156 D; SEQ 01, 02, 03, 04, 05, 06 WITHIN 3 D On Hold Comments: Additional Comments: We request a range of orientations in this first visit and the same orientation in the subsequent visits. Visits are also requested to be executed sequentially within a 3 day period. 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 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1115 S (1115 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1309 S (1309 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1368 S POS TARG 0.148, 0.086 (1368 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1169 S POS TARG 0.148, 0.086 (1169 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1005+3722 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A J1005+3722 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A J1005+3722 3 ACS/WFC ACCUM WFCENTER F814W none none none none 2 N/A J1005+3722 4 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A 16048( 4) - 31-Jan-2020 16:22:56 - [ 5] Visit: 02 (Visit 02) Visit Requirements: SAME ORIENT AS 01; AFTER 01 BY 4 H TO 3 D On Hold Comments: Additional Comments: Please avoid scheduling windows in increments of 12 hours after previous visit. 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 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1115 S POS TARG 0.222, 0.240 (1115 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1309 S POS TARG 0.222, 0.240 (1309 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1368 S POS TARG 0.074, 0.154 (1368 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1169 S POS TARG 0.074, 0.154 (1169 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1005+3722 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A J1005+3722 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A J1005+3722 3 ACS/WFC ACCUM WFCENTER F814W none none none none 2 N/A J1005+3722 4 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A 16048( 4) - 31-Jan-2020 16:22:56 - [ 6] Visit: 03 (Visit 03) Visit Requirements: SAME ORIENT AS 01; AFTER 02 BY 4 H TO 3 D On Hold Comments: Additional Comments: Please avoid scheduling windows in increments of 12 hours after previous visit. 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 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1115 S POS TARG 0.085, 0.105 (1115 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1309 S POS TARG 0.085, 0.105 (1309 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1368 S POS TARG 0.233, 0.191 (1368 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1169 S POS TARG 0.233, 0.191 (1169 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1005+3722 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A J1005+3722 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A J1005+3722 3 ACS/WFC ACCUM WFCENTER F814W none none none none 2 N/A J1005+3722 4 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A 16048( 4) - 31-Jan-2020 16:22:56 - [ 7] Visit: 04 (Visit 04) Visit Requirements: SAME ORIENT AS 01; AFTER 03 BY 4 H TO 3 D On Hold Comments: Additional Comments: Please avoid scheduling windows in increments of 12 hours after previous visit. 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 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1115 S POS TARG 0.307, 0.345 (1115 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1309 S POS TARG 0.307, 0.345 (1309 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1368 S POS TARG 0.159, 0.259 (1368 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1169 S POS TARG 0.159, 0.259 (1169 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1005+3722 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A J1005+3722 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A J1005+3722 3 ACS/WFC ACCUM WFCENTER F814W none none none none 2 N/A J1005+3722 4 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A 16048( 4) - 31-Jan-2020 16:22:56 - [ 8] Visit: 05 (Visit 05) Visit Requirements: SAME ORIENT AS 01; AFTER 04 BY 4 H TO 3 D On Hold Comments: Additional Comments: Please avoid scheduling windows in increments of 12 hours after previous visit. 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 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1105 S POS TARG 0.805, 0.0 (1105 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1299 S POS TARG 0.085, 0.0 (1299 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1368 S POS TARG 0.233, 0.086 (1368 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1169 S POS TARG 0.233, 0.086 (1169 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1005+3722 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A J1005+3722 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A J1005+3722 3 ACS/WFC ACCUM WFCENTER F814W none none none none 2 N/A J1005+3722 4 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A 16048( 4) - 31-Jan-2020 16:22:56 - [ 9] Visit: 06 (Visit 06) Visit Requirements: SAME ORIENT AS 01; AFTER 05 BY 4 H TO 3 D On Hold Comments: Additional Comments: Please avoid scheduling windows in increments of 12 hours after previous visit. 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 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1115 S POS TARG 0.307, 0.240 (1115 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1309 S POS TARG 0.307, 0.240 (1309 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1368 S POS TARG 0.159, 0.154 (1368 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1169 S POS TARG 0.159, 0.154 (1169 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 J1005+3722 ACS/WFC ACCUM WFCENTER F606W 1 1141 S POS TARG 0.0, 0.105 (1141 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 J1005+3722 ACS/WFC ACCUM WFCENTER F814W 1 1371 S POS TARG 0.0, 0.105 (1371 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1005+3722 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A J1005+3722 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A J1005+3722 3 ACS/WFC ACCUM WFCENTER F814W none none none none 2 N/A J1005+3722 4 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A J1005+3722 5 ACS/WFC ACCUM WFCENTER F606W none none none none 3 N/A J1005+3722 6 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A 16048( 4) - 31-Jan-2020 16:22:56 - [ 10] Summary Form for Proposal 16048 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 4 H TO 3 D, AFTER 02 BY 4 H TO 3 D, AFTER 03 BY 4 H TO 3 D, AFTER 04 BY 4 H TO 3 D, AFTER 05 BY 4 H TO 3 D, ORIENT 145D TO 156 D, ORIENT 177D TO 235 D, ORIENT 315D TO 320 D, ORIENT 358D TO 60 D, POS TARG 0.0, 0.105, POS TARG 0.074, 0.154, POS TARG 0.085, 0.0, POS TARG 0.085, 0.105, POS TARG 0.148, 0.086, POS TARG 0.159, 0.154, POS TARG 0.159, 0.259, POS TARG 0.222, 0.240, POS TARG 0.233, 0.086, POS TARG 0.233, 0.191, POS TARG 0.307, 0.240, POS TARG 0.307, 0.345, POS TARG 0.805, 0.0, SAME ORIENT AS 01, SEQ 01, 02, 03, 04, 05, 06 WITHIN 3 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names J1005+3722 ------------------------------------------------------------------------------------------------------------------------------------