17102( 2) - 14-Jul-2022 17:37:50 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17102 Version: 2 Check-in Time: 14-Jul-2022 17:37:50 STScI Edit Number: 0 Title Anchoring CNO with an Extremely Metal Deficient Galaxy ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Danielle Berg University of Texas at Austin Y CoI: Dr. Kristen B W McQuinn Rutgers the State University of New Jersey N CoI: Prof. John Chisholm University of Texas at Austin N CoI: Dr. Evan D. Skillman University of Minnesota - Twin Cities N CoI: Dr. Grace Telford Rutgers the State University of New Jersey N ------------------------------------------------------------------------------------ Abstract While oxygen and nitrogen have been widely observed in spiral and dwarf galaxies, the study of the next most abundant element, carbon, remains relatively unexplored, especially for the lowest metallicities relevant for high-z galaxies. Carbon has no strong collisionally-excited emission lines in the optical, however, by observing the CIII] 1907, 1909 and OIII] 1661, 1666 emission lines in the UV, we can obtain a very secure measurement of the C/O ratio in HII regions. Recent campaigns have been successfully using this method to measure C/O abundances in dwarf galaxies using HST/COS, however, extremely metal poor galaxies (XMPs; 12+log(O/H) < 7.3 or < 3% solar) are notoriously rare and have challengingly faint emission, and so no significant measurements of C/O yet exist for the most metal-poor nearby galaxies. The recent discovery of unexpectedly strong ultraviolet OIII] 1666 and rare NIII] 1750 emission from the HST/COS G160M spectrum of nearby XMP galaxy, Leo P (12+log(O/H)=7.17), reveals a unique opportunity to measure the CNO abundances in a chemically-young, high-ionization galaxy with exceptionally bright emission. We propose HST/COS G140L observations of Leo P to simultaneously measure the C, N, and O abundance in the most metal-poor XMP to date. These observations will allow us to (1) anchor the C/O and C/N relationships by extending the low-metallicity baseline, (2) explore the potential continuity in C/O versus O/H from dwarf galaxies to DLAs, (3) test the proposed link between C and N production, and (4) help constrain rest-frame UV emission-line diagnostics in chemically-young systems in preparation for the distant galaxies that will be observed with JWST. ------------------------------------------------------------------------------------ Observations Description ------------------------ In order to anchor the poorly constrained low-metallicity regime of the C/O-O/H relationship, we will use HST/COS spectroscopic measurements of the OIII] 1661, 1666 and CIII] 1907, 1909 emission lines of the extremely metal-deficient Leo P galaxy. This data will provide a crucial constraint on the C/O relationship in metal-poor dwarf galaxies, which yields important information on the time evolution and nucleosynthetic origins of these elements, and will provide an important template for early galaxy evolution. The most efficient observing strategy for these observations is to use the G140L grating on COS with the 1280 central wavelength setting, which allows simultaneous observations of all 17102( 2) - 14-Jul-2022 17:37:50 - [ 2] the necessary UV emission lines within Segment A. We have excellent input coordinates centered on the NUV surface brightness peak of the O-star Leo P from previous HST/COS observations, allowing us to utilize the time-efficient ACQ/IMAGE mode for target acquisition. Note that while the resolution of COS spectra is degraded for non-point sources, we have demonstrated in Berg+19 that the OIII] doublet is easily resolved and the CIII] doublet can be deblended in G140L spectra (allowing for an estimate of the CIII] electron density), even for targets with extended nebular emission that fills the COS aperture. We split our awarded 16 orbits up into 4 visits based on the updated COS guidelines to reduce observation failures. ------------------------------------------------------------------------------------ 17102( 2) - 14-Jul-2022 17:37:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LEO-P GALAXY, DWARF COMPACT RA=10H21M45.1217S +/- 0.01", J2000 V = 21.51 Galex NUV: 18.81 DEC=+18D05'16.93" +/- 0.01" Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 17102( 2) - 14-Jul-2022 17:37:50 - [ 4] Visit: 01 (G185M) Visit Requirements: 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 LEO-P COS/NUV ACQ/IMA PSA MIRRORA 1 35 S (35 GE S) Comments: The GSC II BOT flags this, but the GALEX BOT determines that it reaches saftey standards. ------------------------------------------------------------------------------------------------------------------------------------ 2 LEO-P COS/FUV TIME-TA PSA G140L 1280 FP-POS=ALL, SEGMENT=BOTH, 1 2381 S G FLASH=YES, BUFFER-TIME=5074 see below (10474 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 1 1 2374.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 2 2 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 3 3 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 4 4 2700.0 S G 17102( 2) - 14-Jul-2022 17:37:50 - [ 5] Visit: 02 (G185M) Visit Requirements: 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 LEO-P COS/NUV ACQ/IMA PSA MIRRORA 1 35 S (35 GE S) Comments: The GSC II BOT flags this, but the GALEX BOT determines that it reaches saftey standards. ------------------------------------------------------------------------------------------------------------------------------------ 2 LEO-P COS/FUV TIME-TA PSA G140L 1280 FP-POS=ALL, SEGMENT=BOTH, 1 2381 S G FLASH=YES, BUFFER-TIME=5074 see below (10474 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 1 1 2374.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 2 2 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 3 3 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 4 4 2700.0 S G 17102( 2) - 14-Jul-2022 17:37:50 - [ 6] Visit: 03 (G185M) Visit Requirements: 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 LEO-P COS/NUV ACQ/IMA PSA MIRRORA 1 35 S (35 GE S) Comments: The GSC II BOT flags this, but the GALEX BOT determines that it reaches saftey standards. ------------------------------------------------------------------------------------------------------------------------------------ 2 LEO-P COS/FUV TIME-TA PSA G140L 1280 FP-POS=ALL, SEGMENT=BOTH, 1 2381 S G FLASH=YES, BUFFER-TIME=5074 see below (10474 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 1 1 2374.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 2 2 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 3 3 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 4 4 2700.0 S G 17102( 2) - 14-Jul-2022 17:37:50 - [ 7] Visit: 04 (G185M) Visit Requirements: 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 LEO-P COS/NUV ACQ/IMA PSA MIRRORA 1 35 S (35 GE S) Comments: The GSC II BOT flags this, but the GALEX BOT determines that it reaches saftey standards. ------------------------------------------------------------------------------------------------------------------------------------ 2 LEO-P COS/FUV TIME-TA PSA G140L 1280 FP-POS=ALL, SEGMENT=BOTH, 1 2381 S G FLASH=YES, BUFFER-TIME=5074 see below (10474 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 1 1 2374.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 2 2 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 3 3 2700.0 S G LEO-P 2 COS/FUV TIME-TA PSA G140L 1280 none none none 4 4 2700.0 S G 17102( 2) - 14-Jul-2022 17:37:50 - [ 8] Summary Form for Proposal 17102 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=5074, FLASH=YES, FP-POS=ALL, SEGMENT=BOTH ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names LEO-P ------------------------------------------------------------------------------------------------------------------------------------