12872( 2) - 10-Jul-2012 17:22:08 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12872 Version: 2 Check-in Time: 10-Jul-2012 17:22:08 STScI Edit Number: 0 Title Characterizing the mass accretion rates in young low-mass stars at low metallicity ------------------------------------------------------------------------------------ Type Cycle GO 20 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Nicola Da Rio European Space Agency - ESTEC Y CoI: Dr. Massimo Robberto Space Telescope Science Institute N CoI: Dr. Dimitrios Gouliermis Max-Planck-Institut fur Astronomie, N Heidelberg CoI: Dr. Guido De Marchi European Space Agency - ESTEC N CoI: Prof. Nino Panagia Space Telescope Science Institute N CoI: Mr. Carlo F. Manara European Southern Observatory - Germany N CoI: Dr. Boyke Rochau Max-Planck-Institut fur Astronomie, N Heidelberg ------------------------------------------------------------------------------------ Abstract Mass accretion from circumstellar disks onto young pre-main sequence (PMS) stars is a key aspect in the evolution of both the central star and the surrounding material. Over the past few years, new observational studies have improved dramatically our knowledge on these accretion processes, in particular thanks to the Hubble Space Telescope. A recent work in the Orion Nebula Cluster - the prototypical few Myr old Galactic star formaing region - allowed us to obtain very accurate measurements of mass accretion rates (Mdot) for ~700 PMS stars. This enabled the analysis of the dependence of Mdot with stellar mass and age with unprecedented accuracy. Moreover, several recent works based on HST Halpha photometry have investigated accretion rates in metal-poor young regions of the Magellanic Clouds (MCs). These studies demonstrate a clear anti-correlation of Mdot with metallicity, but results are limited to intermediate mass stars (M~1Msun). We aim at completing the parameter space of these studies, i.e., study Mdot for low mass stars (down to 0.3 Msun, the peak of the initial mass function) in the Magellanic Clouds. This can be achieved through deep Halpha imaging of a particular region of the LMC, LH 95, whose low-mass PMS population has been already well characterized by us down to 0.2Msun. The methods we will use to derive Mdot from the proposed observations, together with the data already in our hands, have been fully tested in other regions of the MCs. The proposed observations will enable us to probe the role of metallicity in low-mass star formation, in order to set additional constraints on PMS theory. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program is awarded 4 primary orbits with ACS/WFC observations plus 4 parallell orbits with WFC3/UVIS. *The primary observations include, overall, 10 exposures in the ACS/WFC in the filter F658N, on a single pointing (with some dithering between them) 12872( 2) - 10-Jul-2012 17:22:08 - [ 2] *The parallel WFC3/UVIS will image in 3 filters: F555W (2 orbits, visit 1 and 3), F814W (1 orbit, visit 2), F656N (1 orbit, visit 4), for a total of 12 exposures As requested in Phase I, the orient angle must be constrained in order keep our parallel WFC3 observations pointed on the nearby cluster LH91. Therefore all these four orbits must be scheduled with an orient angle between 160 and 164. As requested in Phase I, and if this this is possible during the scheduling of the HST Cycle 20, we would like to have the 4 orbits of this program (4 visits), scheduled as far as possible in time from each other, withing the visibility period. This is useful for us to monitor stellar variability in our targeted cluster LH95. This means that whereas the 4 visits could be carried out sequentially, one after the other, we would benefit if they were scheduled in different (well separated) days. Real Time Justification ----------------------- N/A Calibration Justification ------------------------- N/A Additional Comments ------------------- Important comments concerning the scheduling of this program are described in the "Observing Description". ------------------------------------------------------------------------------------ 12872( 2) - 10-Jul-2012 17:22:08 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LH95 STELLAR CLUSTER, OB RA=05H37M5.0000S +/- 1", J2000 V = 28 ASSOCIATION, OPEN DEC=-66D21'47.00" +/- 1" CLUSTER, STAR FORMING REGION, YOUNG ASSOCIATION Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 12872( 2) - 10-Jul-2012 17:22:08 - [ 4] Visit: 01 Visit Requirements: ORIENT 160D TO 164 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LH95 ACS/WFC ACCUM WFCENTER F658N 1 100 S POS TARG 2, -3; PAR 3-4 see below WITH 1-2 ------------------------------------------------------------------------------------------------------------------------------------ 2 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1200 S POS TARG 2, -3 see below ------------------------------------------------------------------------------------------------------------------------------------ 3 LH95 WFC3/UVI ACCUM UVIS-CENT F555W 1 150 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 4 LH95 WFC3/UVI ACCUM UVIS-CENT F555W 1 1250 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 5 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1400 S POS TARG -2, 3; PAR 6-7 see below WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 LH95 WFC3/UVI ACCUM UVIS-CENT F555W 1 150 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 7 LH95 WFC3/UVI ACCUM UVIS-CENT F555W 1 1250 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LH95 1 ACS/WFC ACCUM WFCENTER F658N none none none none 1 106.0 S LH95 2 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1206.0 S LH95 3 WFC3/UVI ACCUM UVIS-CEN F555W none none none none 1 155.0 S S TER LH95 4 WFC3/UVI ACCUM UVIS-CEN F555W none none none none 1 1255.0 S S TER LH95 5 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1406.0 S LH95 6 WFC3/UVI ACCUM UVIS-CEN F555W none none none none 1 147.0 S S TER LH95 7 WFC3/UVI ACCUM UVIS-CEN F555W none none none none 1 1247.0 S S TER 12872( 2) - 10-Jul-2012 17:22:08 - [ 5] Visit: 02 Visit Requirements: ORIENT 160D TO 164 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LH95 ACS/WFC ACCUM WFCENTER F658N 1 100 S POS TARG -3, 2; PAR 3-4 see below WITH 1-2 ------------------------------------------------------------------------------------------------------------------------------------ 2 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1200 S POS TARG -3, 2 see below ------------------------------------------------------------------------------------------------------------------------------------ 3 LH95 WFC3/UVI ACCUM UVIS-CENT F814W 1 150 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 4 LH95 WFC3/UVI ACCUM UVIS-CENT F814W 1 1250 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 5 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1400 S POS TARG 3, -2; PAR 6-7 see below WITH 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 LH95 WFC3/UVI ACCUM UVIS-CENT F814W 1 150 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 7 LH95 WFC3/UVI ACCUM UVIS-CENT F814W 1 1250 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LH95 1 ACS/WFC ACCUM WFCENTER F658N none none none none 1 106.0 S LH95 2 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1206.0 S LH95 3 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 155.0 S S TER LH95 4 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 1255.0 S S TER LH95 5 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1406.0 S LH95 6 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 147.0 S S TER LH95 7 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 1247.0 S S TER 12872( 2) - 10-Jul-2012 17:22:08 - [ 6] Visit: 03 Visit Requirements: ORIENT 160D TO 164 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1350 S POS TARG 1, 4; PAR 2 see below WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 LH95 WFC3/UVI ACCUM UVIS-CENT F555W 1 1350 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 3 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1350 S POS TARG -1, -4; PAR 4 see below WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 LH95 WFC3/UVI ACCUM UVIS-CENT F555W 1 1350 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LH95 1 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1431.0 S LH95 2 WFC3/UVI ACCUM UVIS-CEN F555W none none none none 1 1515.0 S S TER LH95 3 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1431.0 S LH95 4 WFC3/UVI ACCUM UVIS-CEN F555W none none none none 1 1455.0 S S TER 12872( 2) - 10-Jul-2012 17:22:08 - [ 7] Visit: 04 Visit Requirements: ORIENT 160D TO 164 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1350 S POS TARG 1.7, -1.7; PAR see below 2 WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 LH95 WFC3/UVI ACCUM UVIS-CENT F656N 1 1350 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 3 LH95 ACS/WFC ACCUM WFCENTER F658N 1 1350 S POS TARG -1.7, 1.7; PAR see below 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 LH95 WFC3/UVI ACCUM UVIS-CENT F656N 1 1350 S S ER see below ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LH95 1 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1432.0 S LH95 2 WFC3/UVI ACCUM UVIS-CEN F656N none none none none 1 1515.0 S S TER LH95 3 ACS/WFC ACCUM WFCENTER F658N none none none none 1 1432.0 S LH95 4 WFC3/UVI ACCUM UVIS-CEN F656N none none none none 1 1455.0 S S TER 12872( 2) - 10-Jul-2012 17:22:08 - [ 8] Summary Form for Proposal 12872 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS-CENTER, WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 160D TO 164 D, PAR 2 WITH 1, PAR 3-4 WITH 1-2, PAR 4 WITH 3, PAR 6-7 WITH 5, POS TARG -1, -4, POS TARG -1.7, 1.7, POS TARG -2, 3, POS TARG -3, 2, POS TARG 1, 4, POS TARG 1.7, -1.7, POS TARG 2, -3, POS TARG 3, -2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W, F656N, F658N, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names LH95 ------------------------------------------------------------------------------------------------------------------------------------