13379( 3) - 14-Nov-2013 11:20:32 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13379 Version: 3 Check-in Time: 14-Nov-2013 11:20:32 STScI Edit Number: 0 Title Multiple stellar populations in the young Large Magellanic Cloud cluster NGC1856 ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Antonino Paolo Milone Australian National University Y CoI: Dr. Luigi R. Bedin Osservatorio Astronomico di Padova N CoI: Prof. Giampaolo Piotto Universita degli Studi di Padova N CoI: Dr. Antonio Aparicio Instituto de Astrofisica de Canarias N CoI: Dr. Anna Fabiola Marino Australian National University N CoI: Dr. Matteo Monelli Instituto de Astrofisica de Canarias N CoI: Dr. Andrea J. Bellini Space Telescope Science Institute N CoI: Dr. R. Michael Rich University of California - Los Angeles N ------------------------------------------------------------------------------------ Abstract The recent discovery of multiple sequences in the color-magnitude diagram of Galactic globular clusters have demonstrated that star clusters have experienced a complex star-formation history. Apparently, the only way to explain the main sequence splitting appears to be the product of hot CNO burning, including He, which can be enriched up to an astonishingly high Y~0.40. Recent discoveries have demonstrated that the CMDs of a large fraction of intermediate-age clusters in the Magellanic Clouds (~70 %) are not consistent with the simple, single stellar population hypothesis. The conditions under which star clusters experience the formation of multiple generations remain controversial. A breakthrough understanding of the problem can be provided by the young stellar clusters, where second generation of stars may be forming, or just formed. However, these objects have been poorly studied to date. To properly constraint the multipopulation phenomenon, we propose deep UVIS imaging of the ~300 Myrs old LMC star cluster NGC 1856 which, according to a recent study, is the best candidate to host multiple stellar populations. The proposed observations will allow us to accurately measure possible age difference between the stellar populations providing fundamental clues on the formation mechanism. Our simulations of WFC3 performance suggest that our observing strategy allow us to detect a main sequence split caused by an He difference as small as Delta Y ~0.03. ------------------------------------------------------------------------------------ Observations Description ------------------------ This is a proposal aimed at obtaining high accuracy photometry of the MC cluster NGC 1856 in the UV WFC3/UVIS/F336W and optical WFC3/UVIS/F814W bands. Real Time Justification ----------------------- Calibration Justification ------------------------- 13379( 3) - 14-Nov-2013 11:20:32 - [ 2] Additional Comments ------------------- ------------------------------------------------------------------------------------ 13379( 3) - 14-Nov-2013 11:20:32 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-1856 STELLAR CLUSTER, RA=05H09M30.3900S, J2000 V = 10.06 GLOBULAR CLUSTER DEC=-69D07'45.40" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 13379( 3) - 14-Nov-2013 11:20:32 - [ 4] Visit: 01 Visit Requirements: SCHED 100% On Hold Comments: Additional Comments: NGC-1856 - part 1 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 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 90 S (90 POS TARG -3, -3; PAR 2 S ER S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-1856 ACS/WFC ACCUM WFCENTER F814W FLASH=16 1 42 S (42 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG -3, -3; PAR 4 S ER S) WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG 0, 0; PAR 6 S ER S) WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 704 S (704 POS TARG +3, +3; PAR 8 S ER S) WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC-1856 ACS/WFC ACCUM WFCENTER F814W 1 559 S (559 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-1856 1 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A NGC-1856 3 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 4 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 5 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 6 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 7 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 8 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A 13379( 3) - 14-Nov-2013 11:20:32 - [ 5] Visit: 02 Visit Requirements: SCHED 100%; ORIENT 44D TO 46D FROM 01 On Hold Comments: Additional Comments: NGC-1856 - part 1 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 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 90 S (90 POS TARG -3, -3; PAR 2 S ER S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-1856 ACS/WFC ACCUM WFCENTER F814W FLASH=16 1 42 S (42 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG -3, -3; PAR 4 S ER S) WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG 0, 0; PAR 6 S ER S) WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 704 S (704 POS TARG +3, +3; PAR 8 S ER S) WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC-1856 ACS/WFC ACCUM WFCENTER F814W 1 559 S (559 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-1856 1 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A NGC-1856 3 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 4 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 5 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 6 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 7 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 8 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A 13379( 3) - 14-Nov-2013 11:20:32 - [ 6] Visit: 03 Visit Requirements: SCHED 100%; ORIENT 89D TO 91D FROM 01 On Hold Comments: Additional Comments: NGC-1856 - part 1 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 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 90 S (90 POS TARG -3, -3; PAR 2 S ER S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-1856 ACS/WFC ACCUM WFCENTER F814W FLASH=16 1 42 S (42 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG -3, -3; PAR 4 S ER S) WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG 0, 0; PAR 6 S ER S) WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 704 S (704 POS TARG +3, +3; PAR 8 S ER S) WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC-1856 ACS/WFC ACCUM WFCENTER F814W 1 559 S (559 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-1856 1 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A NGC-1856 3 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 4 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 5 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 6 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 7 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 8 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A 13379( 3) - 14-Nov-2013 11:20:32 - [ 7] Visit: 04 Visit Requirements: SCHED 100%; ORIENT 134D TO 136D FROM 01 On Hold Comments: Additional Comments: NGC-1856 - part 1 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 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 90 S (90 POS TARG -3, -3; PAR 2 S ER S) WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-1856 ACS/WFC ACCUM WFCENTER F814W FLASH=16 1 42 S (42 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG -3, -3; PAR 4 S ER S) WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F336W FLASH=8 1 711 S (711 POS TARG 0, 0; PAR 6 S ER S) WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-1856 ACS/WFC ACCUM WFCENTER F475W 1 665 S (665 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-1856 WFC3/UVI ACCUM UVIS-CENT F814W FLASH=8 1 704 S (704 POS TARG +3, +3; PAR 8 S ER S) WITH 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC-1856 ACS/WFC ACCUM WFCENTER F814W 1 559 S (559 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-1856 1 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A NGC-1856 3 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 4 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 5 WFC3/UVI ACCUM UVIS-CEN F336W none none none none 1 N/A S TER NGC-1856 6 ACS/WFC ACCUM WFCENTER F475W none none none none 1 N/A NGC-1856 7 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-1856 8 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A 13379( 3) - 14-Nov-2013 11:20:32 - [ 8] Summary Form for Proposal 13379 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS-CENTER, WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=16, FLASH=8 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 134D TO 136D FROM 01, ORIENT 44D TO 46D FROM 01, ORIENT 89D TO 91D FROM 01, PAR 2 WITH 1, PAR 4 WITH 3, PAR 6 WITH 5, PAR 8 WITH 7, POS TARG +3, +3, POS TARG -3, -3, POS TARG 0, 0, SCHED 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W, F475W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC-1856 ------------------------------------------------------------------------------------------------------------------------------------