11132( 5) - 06/13/07 09:50 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11132 Version: 5 Check-in Time: 13-Jun-2007 13:49:54 STScI Edit Number: 2 Title Constraining the age of the AB Dor system ------------------------------------------------------------------------------------ Type Cycle Parallel Pointing Tolerance GO 16 ------------------------------------------------------------------------------------ Investigators Contact? PI: Mr. Markus R. Janson Max-Planck-Institut fur Astronomie, Heidelberg CoI: Dr. Wolfgang Brandner University of California - Los Angeles N CoI: Prof. Thomas K. Henning Max-Planck-Institut fur Astronomie, N Heidelberg ------------------------------------------------------------------------------------ Abstract The zero-age main sequence K-type star AB Dor, with an age of 25 to 125 Myr, is the most active young star in the solar neighbourhood. It is part of a quadruple system of young stars. The mass of AB Dor C, the closest and lowest mass companion, has been derived from astrometric observations (with the VLA and adaptive optics at the VLT) to 94+-3 times the mass of Jupiter. The low mass (close to the hydrogen burning limit) combined with the young age makes AB Dor C a unique calibration source for evolutionary tracks for very low-mass stars and brown dwarfs, provided that a precise age estimate can be derived for the system. We propose to use the HST planetary camera to obtain resolved component photometry of the M-type pre-main sequence star AB Dor Ba and Bb in order to derive individual spectral types and luminosities, which will enable us to age-date the AB Dor system to better than +-20 Myr. In addition, the observations will help to constrain the Ba/Bb orbit, and hence to derive dynamical mass estimates as well. ------------------------------------------------------------------------------------ 11132( 5) - 06/13/07 09:50 - [ 2] Observations Description ------------------------ Seven exposures in six filters (F502N, F555W, F622W, F658N, F791W and F850LP) will be taken within a four-point dither pattern. Two exposures per dither position are taken with the F502N filter, once with a short exposure time in order not to saturate AB Dor A, and once with a long exposure time in order to achieve a good SNR for AB Dor Ba/Bb. Both AB Dor A and AB Dor Ba/Bb are included in all frames. Since a little bit of time remains in the second orbit after the dither loop has finished, we include also one exposure in the F439W filter, which can be used to estimate veiling effects of material accreting on the stars in the UV. Changed F658N filter to the correct WFPC2 H-alpha filter F656N, per the IS suggestion. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 11132( 5) - 06/13/07 09:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AB-DOR-B STAR, M V-IV RA=05H28M44.5000S +/- 1", DEC=- J2000 V = 13.0 65D26'47.00" +/- 1" Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. However, due to the presence of AB Dor A, the coordinates of AB Dor B were only accurate down to an arcminute. The coordinates were therefore subsequently changed based on NACO images to more accurately represent the position of AB Dor B. 11132( 5) - 06/13/07 09:50 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFPC2-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.559017 Line_Spacing 0.559017 Coordinate_Frame POS-TARG Pattern_Orient 26.56505 Angle_Between_Sides 143.130102 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 11132( 5) - 06/13/07 09:50 - [ 5] Visit: 01 Visit Priority: Visit Requirements: 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 AB-DOR-B WFPC2 IMAGE PC1 F622W ATD-GAIN=15 1 2 S PATTERN 1 1-7 ------------------------------------------------------------------------------------------------------------------------------------ 2 AB-DOR-B WFPC2 IMAGE PC1 F656N ATD-GAIN=15 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 3 AB-DOR-B WFPC2 IMAGE PC1 F791W ATD-GAIN=15 1 2 S ------------------------------------------------------------------------------------------------------------------------------------ 4 AB-DOR-B WFPC2 IMAGE PC1 F850LP ATD-GAIN=15 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 5 AB-DOR-B WFPC2 IMAGE PC1 F555W ATD-GAIN=15 1 4 S ------------------------------------------------------------------------------------------------------------------------------------ 6 AB-DOR-B WFPC2 IMAGE PC1 F502N ATD-GAIN=15 1 1 S ------------------------------------------------------------------------------------------------------------------------------------ 7 AB-DOR-B WFPC2 IMAGE PC1 F502N ATD-GAIN=15 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 8 AB-DOR-B WFPC2 IMAGE PC1 F439W ATD-GAIN=15 1 40 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 | ------------------------------------------------------------------------------------------------------------------------------------ AB-DOR-B 1 WFPC2 IMAGE PC1 F622W 1 none none none 1 N/A AB-DOR-B 1 WFPC2 IMAGE PC1 F622W 2 none none none 1 N/A AB-DOR-B 1 WFPC2 IMAGE PC1 F622W 3 none none none 1 N/A AB-DOR-B 1 WFPC2 IMAGE PC1 F622W 4 none none none 2 N/A AB-DOR-B 2 WFPC2 IMAGE PC1 F656N 1 none none none 1 N/A AB-DOR-B 2 WFPC2 IMAGE PC1 F656N 2 none none none 1 N/A AB-DOR-B 2 WFPC2 IMAGE PC1 F656N 3 none none none 2 N/A AB-DOR-B 2 WFPC2 IMAGE PC1 F656N 4 none none none 2 N/A AB-DOR-B 3 WFPC2 IMAGE PC1 F791W 1 none none none 1 N/A AB-DOR-B 3 WFPC2 IMAGE PC1 F791W 2 none none none 1 N/A AB-DOR-B 3 WFPC2 IMAGE PC1 F791W 3 none none none 2 N/A AB-DOR-B 3 WFPC2 IMAGE PC1 F791W 4 none none none 2 N/A AB-DOR-B 4 WFPC2 IMAGE PC1 F850LP 1 none none none 1 N/A AB-DOR-B 4 WFPC2 IMAGE PC1 F850LP 2 none none none 1 N/A AB-DOR-B 4 WFPC2 IMAGE PC1 F850LP 3 none none none 2 N/A AB-DOR-B 4 WFPC2 IMAGE PC1 F850LP 4 none none none 2 N/A AB-DOR-B 5 WFPC2 IMAGE PC1 F555W 1 none none none 1 N/A AB-DOR-B 5 WFPC2 IMAGE PC1 F555W 2 none none none 1 N/A AB-DOR-B 5 WFPC2 IMAGE PC1 F555W 3 none none none 2 N/A 11132( 5) - 06/13/07 09:50 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AB-DOR-B 5 WFPC2 IMAGE PC1 F555W 4 none none none 2 N/A AB-DOR-B 6 WFPC2 IMAGE PC1 F502N 1 none none none 1 N/A AB-DOR-B 6 WFPC2 IMAGE PC1 F502N 2 none none none 1 N/A AB-DOR-B 6 WFPC2 IMAGE PC1 F502N 3 none none none 2 N/A AB-DOR-B 6 WFPC2 IMAGE PC1 F502N 4 none none none 2 N/A AB-DOR-B 7 WFPC2 IMAGE PC1 F502N 1 none none none 1 N/A AB-DOR-B 7 WFPC2 IMAGE PC1 F502N 2 none none none 1 N/A AB-DOR-B 7 WFPC2 IMAGE PC1 F502N 3 none none none 2 N/A AB-DOR-B 7 WFPC2 IMAGE PC1 F502N 4 none none none 2 N/A AB-DOR-B 8 WFPC2 IMAGE PC1 F439W none none none none 2 N/A 11132( 5) - 06/13/07 09:50 - [ 7] Summary Form for Proposal 11132 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1-7; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F622W F656N F791W F850LP F555W F502N F439W ------------------------------------------------------------------------------------------------------------------------------------ Target Names AB-DOR-B ------------------------------------------------------------------------------------------------------------------------------------