14687( 3) - 20-Jul-2016 15:29:10 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14687 Version: 3 Check-in Time: 20-Jul-2016 15:29:10 STScI Edit Number: 0 Title The Origin of the Leading Arm of the Magellanic Stream ------------------------------------------------------------------------------------ Type Cycle GO 24 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Andrew J. Fox Space Telescope Science Institute - ESA Y CoI: Dr. Kat A Barger Texas Christian University N CoI: Dr. Nicolas Lehner University of Notre Dame N CoI: Dr. Dana Ioana Casetti Southern Connecticut State University N CoI: Prof. Jay Christopher Howk University of Notre Dame N CoI: Prof. Paul A. Crowther University of Sheffield N CoI: Prof. Philipp Richter Universitat Potsdam N CoI: Dr. Elena D'Onghia University of Wisconsin - Madison N ------------------------------------------------------------------------------------ Abstract A vast debris field of gas connects the Magellanic Clouds and the Milky Way. Known as the Leading Arm (LA), this structure is actively feeding the Galactic disk with new fuel for star formation. Three main concentrations of gas exist, named LA I, LA II, and LA III, but the metallicity has only been measured in one of these three (S/H=0.25+/-0.07 solar in LA II), and the physical connections between the regions are unclear. Here we propose COS FUV spectroscopy of two additional targets (one star and one QSO) that probe LA I and LA III, to map the LA metallicity as a function of position. By comparing the LA chemical abundances in each region we will directly test models of LA formation (single stripping event vs multiple episodes) and therefore constrain the dynamics of the Magellanic System. The observations will also provide measurements of the dust content of the LA via the S/Fe ratio, and the high-ion content via the Si IV doublet, which traces the interaction between the LA and the hot halo of the Milky Way. Overall, this program will form a case study of the only gas structure accreting onto the Milky Way that can be traced to a neighboring galaxy, and will therefore explore the mechanisms by which galaxies fuel their star formation. ------------------------------------------------------------------------------------ Observations Description ------------------------ This is a 6-orbit proposal to observe two targets (one star and one QSO) in the direction of the Leading Arm of the Magellanic Stream. V01 observes a QSO (UVQSJ101629.20-315023.6, z=0.24) with the G130M/1291 setting, for four orbits. It uses an ACQ/SEARCH (2x2) and an ACQ/IMAGE, both with MIRRORB. V02 observes a B V star (CD14-A05, T_eff=15000; spectral type B5 IV, this target is not in SIMBAD since it was discovered and characterized by members of our team), for two orbits total, one with G130M/1291 and one with G160M/1600. This also uses an ACQ/SEARCH (2x2) and ACQ/IMAGE, both with MIRRORB. 14687( 3) - 20-Jul-2016 15:29:10 - [ 2] Note that CD14-A05 was not in the original Phase I proposal. Our original stellar target was SPM4.0. However, observations obtained after the Phase I deadline revealed that this target was a sub-dwarf, much closer than previously thought, and of no connection to the Leading Arm. Therefore we requested a target switch to CD14-A05 in HOPR 85049, approved by the TTRB on 7/7/16. ------------------------------------------------------------------------------------ 14687( 3) - 20-Jul-2016 15:29:10 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 UVQSJ101629. ISM, ABSORPTION LINE RA=10H16M29.2080S +/- 0.4", J2000 V = 18.45 FUV=17.32, NUV=17.13, 20-315023.6 SYSTEM - GALACTIC, HIGH DEC=-31D50'23.64" +/- 0.4" Magnitude given above is B (V VELOCITY CLOUD, TIDAL unavailable) TAIL Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 2 CD14-A05 STAR, B3-B5 V-IV RA=11H10M58.3400S +/- 0.4", J2000 V = 15.8 GALEX NUV=16.83, FUV=16.70 DEC=-73D14'9.63" +/- 0.4" Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 14687( 3) - 20-Jul-2016 15:29:10 - [ 4] Visit: 01 (UVQSJ1016) 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 UVQSJ101629 COS/NUV ACQ/SEA PSA MIRRORB SCAN-SIZE=2, STEP-SIZE=1.767, 1 49 S (49 .20-315023. RCH CENTER=FLUX-WT S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 2 UVQSJ101629 COS/NUV ACQ/IMA PSA MIRRORB 1 49 S (49 .20-315023. GE S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 3 UVQSJ101629 COS/FUV TIME-TA PSA G130M 1291 FP-POS=1, BUFFER-TIME=3546 1 2086 S .20-315023. G (2086 S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 4 UVQSJ101629 COS/FUV TIME-TA PSA G130M 1291 FP-POS=2, BUFFER-TIME=3546 1 2958 S .20-315023. G (2958 S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 5 UVQSJ101629 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=3546 1 2958 S .20-315023. G (2958 S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 6 UVQSJ101629 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=3546 1 2958 S .20-315023. G (2958 S) 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 | ------------------------------------------------------------------------------------------------------------------------------------ UVQSJ101629.20-3150 1 COS/NUV ACQ/SEA PSA MIRRORB none none none none 1 N/A 23.6 RCH UVQSJ101629.20-3150 2 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 23.6 GE UVQSJ101629.20-3150 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 23.6 G UVQSJ101629.20-3150 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 23.6 G UVQSJ101629.20-3150 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 23.6 G UVQSJ101629.20-3150 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 23.6 G 14687( 3) - 20-Jul-2016 15:29:10 - [ 5] Visit: 02 (CD14-A05) 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 CD14-A05 COS/NUV ACQ/SEA PSA MIRRORB CENTER=FLUX-WT, SCAN-SIZE=2, 1 36 S (36 RCH STEP-SIZE=1.767 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CD14-A05 COS/NUV ACQ/IMA PSA MIRRORB 1 36 S (36 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CD14-A05 COS/FUV TIME-TA PSA G130M 1291 FP-POS=ALL, BUFFER-TIME=2700 1 542 S G (2168 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CD14-A05 COS/FUV TIME-TA PSA G160M 1600 FP-POS=ALL, BUFFER-TIME=2700 1 734 S G (2936 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 | ------------------------------------------------------------------------------------------------------------------------------------ CD14-A05 1 COS/NUV ACQ/SEA PSA MIRRORB none none none none 1 N/A RCH CD14-A05 2 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE CD14-A05 3 COS/FUV TIME-TA PSA G130M 1291 none none none 1 1 N/A G CD14-A05 3 COS/FUV TIME-TA PSA G130M 1291 none none none 2 1 N/A G CD14-A05 3 COS/FUV TIME-TA PSA G130M 1291 none none none 3 1 N/A G CD14-A05 3 COS/FUV TIME-TA PSA G130M 1291 none none none 4 1 N/A G CD14-A05 4 COS/FUV TIME-TA PSA G160M 1600 none none none 1 2 N/A G CD14-A05 4 COS/FUV TIME-TA PSA G160M 1600 none none none 2 2 N/A G CD14-A05 4 COS/FUV TIME-TA PSA G160M 1600 none none none 3 2 N/A G CD14-A05 4 COS/FUV TIME-TA PSA G160M 1600 none none none 4 2 N/A G 14687( 3) - 20-Jul-2016 15:29:10 - [ 6] Summary Form for Proposal 14687 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, ACQ/SEARCH, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=2700, BUFFER-TIME=3546, CENTER=FLUX-WT, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, FP-POS=ALL, SCAN-SIZE=2, STEP-SIZE=1.767 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names CD14-A05, UVQSJ101629.20-315023.6 ------------------------------------------------------------------------------------------------------------------------------------