Assigned ID: 969 ----- Attempting Submission 1 (Sat Feb 25 00:13:10 GMT 2012) ----- ----- Attempting Submission 1 (Tue Jul 10 15:36:05 GMT 2012) ----- Characterizing the mass accretion rates in young low-mass stars at low metallicity 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. 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) *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. N/A N/A Important comments concerning the scheduling of this program are described in the "Observing Description". RESOLVED STELLAR POPULATIONS 12 false 0.0 0.0 false false false false SUPPORTED STELLAR CLUSTER OB ASSOCIATION OPEN CLUSTER STAR FORMING REGION YOUNG ASSOCIATION This object was generated by the targetselector and retrieved from the SIMBAD database. 2MASS-J05370431-6622007 J2000 J2000 ACS/WFC Imaging No No F658N WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F658N WFC3/UVIS Imaging No No F814W C:\Users\Nicola\AppData\Local\Temp\OPVisit457187143556667821.xml The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. 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(Tic-Visit :proposal-id 12872 :visit-id "02" :proposal-version -1 :trans-version "20120604" :date "10-Jul-2012 17:33:23.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2007664 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12872 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12872 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3246 :al-overhead-at-end 110 :internal-dur-at-end 699 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3582 :pcs-gap 0 ) true 1 0 C:\Users\Nicola\AppData\Local\Temp\OPVisit1083619346955283334.xml The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. 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