0----- Attempting Submission 1 (Sun Jul 10 14:46:37 GMT 2016) -----The Primordial Binary Fraction in Trumpler 14: Frequency and Multiplicity ParametersThis is an astrometric proposal designed to identify and characterize the properties of medium- and long-period (orbital periods ranging from 1.8 to 100 years) visual binaries in the mass range between ~4 and 20 Mo in the young compact cluster Trumpler 14 in the Carina Nebula. We aim to probe the virtually unexplored population of intermediate- and high-mass binaries that will experience a Roche-lobe overflow during their post-main-sequence evolution. These binaries are of particular interest because they are expected to be the progenitors of supernovae Type Ia, b, and c, X-ray binaries, double neutron stars and double black holes. Multiplicity properties of young stars can be further used to constrain the outcome of the star-formation process and hence distinguish between various formation scenarios. The medium- and long-period binaries (P> 0.5 yr) are hard to detect and expensive to characterize with traditional ground-based spectroscopy. Knowledge of their orbital properties is however crucial to properly estimate the overall fraction of OB stars whose evolution is affected by binary interaction and to predict the outcome of such interaction. Because of the well characterized PSF of WFC3/UVIS and its temporal stability, HST is the only facility able to characterize the properties of OB-type medium-period binaries in Tr14, and Tr14 is the only nearby high-density OB-type young cluster.This is the second epoch of a three year-long proposal, designed to characterize intermediate and long period binaries by measuring their orbital parameters such as orbital period, mass ratio, orbital separation and eccentricity.
The binaries we are looking for are barely resolved and require a very careful characterization of the PSF. For this reason we are acquiring as many exposures as possible within each orbit. This will allow us not only to derive the most accurate PSF library for each epoch, but also to obtain a very well characterized geometric distortion calibration in two narrow band filters.
We are repeating the observing strategy designed for the first cycle. Observations have been organized in two visits:
1) Visit 01 will observe Tr14 only in the filter F631N and should be executed between March and April
2) Visit 02 will use the Tr14 again in both filters F631N and F953N; this visit should be be execute at the end of the cycle between August and September.
Orientation angles have been chosen to be consistent with the requested observing window. Eleven e- of postflash have been added to each exposure to mitigate the effects of CTE. Because of the very high backgroun (Tr14 is in the Carina Nebula) we will use the first epoch dataset to carefuly verify that the ammount of postflash is not too high.
In the phaseI we asked to observe Tr14 using subarray 2Kx2K, in preparing the phaseII we realized that using full frame observations will not affect the quality of pour astrometry, but will allow us to increase the fraction of monitored stars, therefore we have slightly modified our observing strategy.RESOLVED STELLAR POPULATIONS12falsefalsefalsefalsefalsefalseAVAILABLESTELLAR CLUSTEREMISSION LINE NEBULAOB ASSOCIATIONSTAR FORMING REGIONYOUNG ASSOCIATIONThis object was generated by the targetselector and retrieved from the SIMBAD database.J2000J2000WFC3/UVISImagingNoNoF631NWFC3/UVISImagingNoNoF953NWFC3/UVISImagingNoNoF631NWFC3/UVISImagingNoNoF631NWFC3/UVISImagingNoNoF953NWFC3/UVISImagingNoNoF631NWFC3/UVISImagingNoNoF631NWFC3/UVISImagingNoNoF953NWFC3/UVISImagingNoNoF631NWFC3/UVISImagingNoNoF631NWFC3/UVISImagingNoNoF953NThe scheduling data was generated by CASM 24.2.CASM was run in Phase II mode./Users/sabbi/Science/PROPOSALS/phase2/GO-14647/OP-cache/GO-14647-v01.xml(Tic-Visit
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