13673( 2) - 15-Jul-2014 17:01:10 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13673 Version: 2 Check-in Time: 15-Jul-2014 17:01:10 STScI Edit Number: 0 Title The Metallicity Dependence of the Initial Mass Function ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Jason S. Kalirai Space Telescope Science Institute Y CoI: Dr. Mark R. Krumholz University of California - Santa Cruz N CoI: Dr. Charlie Conroy University of California - Santa Cruz N CoI: Dr. Aaron Dotter Australian National University N CoI: Dr. Noelia Noel University of Surrey N CoI: Dr. Ricardo Carrera Instituto de Astrofisica de Canarias N CoI: Prof. Anil C. Seth University of Utah N CoI: Prof. Jay Strader Michigan State University N ------------------------------------------------------------------------------------ Abstract We propose to measure the metallicity dependence of the initial mass function (IMF), through a high-precision study of the stellar luminosity function in a remote halo field of the Small Magellanic Cloud (SMC). In a previous HST investigation of an [Fe/H] = -1.1 SMC halo field, we achieved one of the most accurate measurements of the stellar IMF to date. Based on resolved photometry of 10, 000 stars, we demonstrated that the IMF over a mass of M = 0.37 to 0.93 Msun is a single power law with slope \alpha = -1.90 (dN/dM = M^\alpha; 3-sigma uncertainty of +0.15, -0.10). Comparing our measurement directly to high-precision local studies of the stellar IMF for stars with the same mass range but [Fe/H] = 0 provides firm new evidence that the IMF is flattening at low metallicities. Using 6 orbits on HST, we propose to now compare our IMF from the Kalirai et al. (2013) study to a new SMC halo field with a very similar set of general properties (e.g., density, star formation history, distance, binary fraction), yet one that is 3 times more metal-poor at [Fe/H] = -1.6. This new field has been carefully chosen from a large ground-based imaging and VLT multiobject spectroscopic survey as the most metal-poor population that is well characterized in the Magellenic Clouds. Using both the ACS and WFC3 instruments simultaneously on HST, we will measure ~3000 stars along the unevolved main-sequence of this population from F606W = 23 - 28.1. Over a mass range of M = 0.40 to 0.90 Msun, these measurements will provide a controlled experiment to determine the power-law slope of the IMF to an accuracy of 0.20, and yield a sensitive characterization of its metallicity dependence. ------------------------------------------------------------------------------------ Observations Description ------------------------ Visits 1 and 2 each target one field in the SMC halo with ACS (primary) and WFC3 (parallel). Each visit has 3 orbits in it, consisting of 6 exposures in F606W and 4 exposures in F814W in both camera. All exposures are dithered. The two fields in each respective visit are offset and placed in locations of the SMC halo that overlap our ground based spectroscopy and avoid obvious bright stars. The same orientation should be used in both visits. 13673( 2) - 15-Jul-2014 17:01:10 - [ 2] ------------------------------------------------------------------------------------ 13673( 2) - 15-Jul-2014 17:01:10 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 QJ0033-1 GALAXY, MAGELLANIC RA=00H33M41.0000S, J2000 V = 23 IRREGULAR DEC=-70D26'30.00" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 QJ0033-2 GALAXY, MAGELLANIC RA=00H33M55.0000S, J2000 V = 23 IRREGULAR DEC=-70D30'7.00" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 13673( 2) - 15-Jul-2014 17:01:10 - [ 4] Visit: 01 Visit Requirements: ORIENT 323D TO 335 D; ORIENT 237D TO 258 D; ORIENT 143D TO 179 D 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 QJ0033-1 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 915 S (915 POS TARG -0.312867, S) -0.848667; PAR 2 WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 995 S (995 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 QJ0033-1 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 915 S (915 POS TARG 0.107033, S) -0.814667; PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 945 S (945 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 5 QJ0033-1 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 915 S (915 POS TARG 0.0576333, S) -0.596367; PAR 6 WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1040 S S ER (1040 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 QJ0033-1 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 975 S (975 POS TARG -0.115267, S) -3.659767; PAR 8 WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1010 S S ER (1010 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 QJ0033-1 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 975 S (975 POS TARG 0.354033, S) -3.720667; PAR 10 WITH 9 ------------------------------------------------------------------------------------------------------------------------------------ 10 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1010 S S ER (1010 S) ------------------------------------------------------------------------------------------------------------------------------------ 11 QJ0033-1 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 975 S (975 POS TARG 0.478033, S) -3.488667; PAR 12 WITH 11 ------------------------------------------------------------------------------------------------------------------------------------ 12 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1100 S S ER (1100 S) ------------------------------------------------------------------------------------------------------------------------------------ 13 QJ0033-1 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 720 S (720 POS TARG -0.312867, S) -0.848667; PAR 14 WITH 13 ------------------------------------------------------------------------------------------------------------------------------------ 13673( 2) - 15-Jul-2014 17:01:10 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 14 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 800 S (800 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 15 QJ0033-1 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 670 S (670 POS TARG 0.107033, S) -0.814667; PAR 16 WITH 15 ------------------------------------------------------------------------------------------------------------------------------------ 16 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 17 QJ0033-1 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 670 S (670 POS TARG 0.0576333, S) -3.596367; PAR 18 WITH 17 ------------------------------------------------------------------------------------------------------------------------------------ 18 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 19 QJ0033-1 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 620 S (620 POS TARG -0.115267, S) -3.659767; PAR 20 WITH 19 ------------------------------------------------------------------------------------------------------------------------------------ 20 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 700 S (700 S ER 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 | ------------------------------------------------------------------------------------------------------------------------------------ QJ0033-1 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A ANY 2 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 1 N/A S TER QJ0033-1 3 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A ANY 4 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 1 N/A S TER QJ0033-1 5 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A ANY 6 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 1 N/A S TER QJ0033-1 7 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A ANY 8 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 2 N/A S TER QJ0033-1 9 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A ANY 10 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 2 N/A S TER QJ0033-1 11 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A 13673( 2) - 15-Jul-2014 17:01:10 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ANY 12 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 2 N/A S TER QJ0033-1 13 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 14 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER QJ0033-1 15 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 16 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER QJ0033-1 17 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 18 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER QJ0033-1 19 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 20 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER 13673( 2) - 15-Jul-2014 17:01:10 - [ 7] Visit: 02 Visit Requirements: SAME ORIENT AS 01 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 QJ0033-2 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 915 S (915 POS TARG -0.312867, S) -0.848667; PAR 2 WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 995 S (995 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 QJ0033-2 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 915 S (915 POS TARG 0.107033, S) -0.814667; PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 945 S (945 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 5 QJ0033-2 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 915 S (915 POS TARG 0.0576333, S) -0.596367; PAR 6 WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1040 S S ER (1040 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 QJ0033-2 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 975 S (975 POS TARG -0.115267, S) -3.659767; PAR 8 WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1010 S S ER (1010 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 QJ0033-2 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 975 S (975 POS TARG 0.354033, S) -3.720667; PAR 10 WITH 9 ------------------------------------------------------------------------------------------------------------------------------------ 10 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1010 S S ER (1010 S) ------------------------------------------------------------------------------------------------------------------------------------ 11 QJ0033-2 ACS/WFC ACCUM WFCENTER F606W CR-SPLIT=NO 1 975 S (975 POS TARG 0.478033, S) -3.488667; PAR 12 WITH 11 ------------------------------------------------------------------------------------------------------------------------------------ 12 ANY WFC3/UVI ACCUM UVIS-CENT F606W CR-SPLIT=NO 1 1100 S S ER (1100 S) ------------------------------------------------------------------------------------------------------------------------------------ 13 QJ0033-2 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 720 S (720 POS TARG -0.312867, S) -0.848667; PAR 14 WITH 13 ------------------------------------------------------------------------------------------------------------------------------------ 13673( 2) - 15-Jul-2014 17:01:10 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 14 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 800 S (800 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 15 QJ0033-2 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 670 S (670 POS TARG 0.107033, S) -0.814667; PAR 16 WITH 15 ------------------------------------------------------------------------------------------------------------------------------------ 16 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 17 QJ0033-2 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 670 S (670 POS TARG 0.0576333, S) -3.596367; PAR 18 WITH 17 ------------------------------------------------------------------------------------------------------------------------------------ 18 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 19 QJ0033-2 ACS/WFC ACCUM WFCENTER F814W CR-SPLIT=NO 1 620 S (620 POS TARG -0.115267, S) -3.659767; PAR 20 WITH 19 ------------------------------------------------------------------------------------------------------------------------------------ 20 ANY WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO 1 700 S (700 S ER 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 | ------------------------------------------------------------------------------------------------------------------------------------ QJ0033-2 1 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A ANY 2 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 1 N/A S TER QJ0033-2 3 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A ANY 4 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 1 N/A S TER QJ0033-2 5 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A ANY 6 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 1 N/A S TER QJ0033-2 7 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A ANY 8 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 2 N/A S TER QJ0033-2 9 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A ANY 10 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 2 N/A S TER QJ0033-2 11 ACS/WFC ACCUM WFCENTER F606W none none none none 2 N/A 13673( 2) - 15-Jul-2014 17:01:10 - [ 9] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ANY 12 WFC3/UVI ACCUM UVIS-CEN F606W none none none none 2 N/A S TER QJ0033-2 13 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 14 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER QJ0033-2 15 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 16 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER QJ0033-2 17 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 18 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER QJ0033-2 19 ACS/WFC ACCUM WFCENTER F814W none none none none 3 N/A ANY 20 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 3 N/A S TER 13673( 2) - 15-Jul-2014 17:01:10 - [ 10] Summary Form for Proposal 13673 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS-CENTER, WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 143D TO 179 D, ORIENT 237D TO 258 D, ORIENT 323D TO 335 D, PAR 10 WITH 9, PAR 12 WITH 11, PAR 14 WITH 13, PAR 16 WITH 15, PAR 18 WITH 17, PAR 2 WITH 1, PAR 20 WITH 19, PAR 4 WITH 3, PAR 6 WITH 5, PAR 8 WITH 7, POS TARG 0.107033, -0.814667, POS TARG 0.354033, -3.720667, POS TARG -0.115267, -3.659767, POS TARG -0.312867, -0.848667, POS TARG 0.0576333, -0.596367, POS TARG 0.0576333, -3.596367, POS TARG 0.478033, -3.488667, SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ANY, QJ0033-1, QJ0033-2 ------------------------------------------------------------------------------------------------------------------------------------