15172( 3) - 28-Aug-2017 20:09:31 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15172 Version: 3 Check-in Time: 28-Aug-2017 20:09:31 STScI Edit Number: 0 Title Validating early stellar encounters as the cause of dynamically hot planetary systems ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Paul George Kalas University of California - Berkeley Y CoI: Dr. Thomas M. Esposito University of California - Berkeley N CoI: Dr. James R. Graham University of California - Berkeley N CoI: Dr. Michael P. Fitzgerald University of California - Los Angeles N CoI: Dr. Gaspard Duchene University of California - Berkeley N CoI: Dr. Grant Kennedy The University of Warwick N CoI: Dr. Mark Booth Universitat Jena N CoI: Dr. Andrew Shannon The Pennsylvania State University N CoI: Dr. Jean-Francois Lestrade Observatoire de Paris N ------------------------------------------------------------------------------------ Abstract One of the key questions concerning exoplanetary systems is why some are dynamically cold, such as TRAPPIST-1, whereas others are dynamically hot, with highly eccentric planets and/or perturbed debris disks. Dynamical theory describes a variety of plausible mechanisms, but few can be empirically tested since the critical dynamical evolution that sets the final planetary architecture is short-lived. One rare system available for testing dynamical upheaval scenarios is the 400 Myr-old Fomalhaut system. In Cycle 22 we coronagraphically studied Fomalhaut C, which is a wide M-dwarf companion to Fomalhaut A, in order to test our prediction that the unresolved, Herschel-detected debris disk around Fomalhaut C may be highly perturbed because of a recent close interaction with Fomalhaut A. Using HST/STIS we discovered a highly asymmetric feature extending northward of Fomalhaut C by 3" that resembles our model of a dynamically hot disk. However, it may be a background galaxy and the definitive test of its physical relationship to Fomalhaut C is to demonstrate common proper motion. Using Keck adaptive optics follow-up observations in J band, we did not detect the feature, and hence follow-up HST observations are the only way to test for common proper motion. Here we request a very small program to revisit Fomalhaut C with STIS in order to validate the initial discovery as a debris disk (1" proper motion between HST epochs). The astrophysical significance is demonstrating that the Fomalhaut system is a valuable case for studying dynamical upheavals via stellar encounters that are inferred to occur in the evolution of many other planetary systems. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our observing plan builds on the successful Cycle 22 observing sequence (GO-13725). The absolute roll constraints are chosen so that the circumstellar feature (PA = 0 degrees) will not intersect the diffraction spikes or BAR5. Scheduling windows appear to be available through the end of November 2017. Fomalhaut C will be occulted at the bent finger with width ~0.3". The bent 15172( 3) - 28-Aug-2017 20:09:31 - [ 2] finger (BAR 5) is a newly supported coronagraphic mode for STIS that is ideal for fainter targets such as Fomalhaut C (Gaspar & Schneider, GO-12923). Two orbits of integration on Fomalhaut C will be executed at two different telescope ORIENTs separated from each other by 25-30 degrees, with ORIENTs selected to avoid having the disk feature behind a diffraction spike or the finger obscuration. A GROUP WITHIN 1.9 orbits is specified in order to achieve two contiguous, non-interrupted orbits to achieve PSF stability (needed for PSF subtraction during data reduction). To go to BAR5, the acquision is on BAR10 and each exposure has a POS TARG X = 16.34596, Y = -7.20172 arcsec. Though a BAR5 aperture is available in the APT, from Cycle 22 we know that the BAR10 acquision combined with this POS TARG places the target at the tip of the bent finger instead of farther down the bent finger (closer to the right edge of the CCD). ------------------------------------------------------------------------------------ 15172( 3) - 28-Aug-2017 20:09:31 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 -ALF-PSA-C STAR, DISK RA=22H48M4.4700S +/- 0.1", J2000 V = 12.624 DEC=-24D22'7.50" +/- 0.1" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 0.024432741291624368 -0.17751 0.130 ------------------------------------------------------------------------------------------------------------------------------------ 15172( 3) - 28-Aug-2017 20:09:31 - [ 4] Visit: 01 (Fom C - Roll 1) Visit Requirements: ORIENT 28D TO 45 D; ORIENT 225D TO 227 D; GROUP 01, 02 WITHIN 1.9 Orbits 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 -ALF-PSA-C STIS/CCD ACQ 50CCD MIRROR 1 0.8 S (0.8 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -ALF-PSA-C STIS/CCD ACCUM BAR10 MIRROR CR-SPLIT=6, GAIN=4 1 2274 S POS TARG 16.34596, (2274 S) -7.20172 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ -ALF-PSA-C 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 1 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 2 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 3 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 4 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 5 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 6 1 N/A 15172( 3) - 28-Aug-2017 20:09:31 - [ 5] Visit: 02 (Fom C - Roll 2) Visit Requirements: ORIENT 25D TO 30D FROM 01 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 -ALF-PSA-C STIS/CCD ACQ 50CCD MIRROR 1 0.8 S (0.8 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -ALF-PSA-C STIS/CCD ACCUM BAR10 MIRROR CR-SPLIT=6, GAIN=4 1 2274 S POS TARG 16.34596, (2274 S) -7.20172 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ -ALF-PSA-C 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 1 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 2 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 3 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 4 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 5 1 N/A -ALF-PSA-C 2 STIS/CCD ACCUM BAR10 MIRROR none none none 6 1 N/A 15172( 3) - 28-Aug-2017 20:09:31 - [ 6] Summary Form for Proposal 15172 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 50CCD, BAR10 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=6, GAIN=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 01, 02 WITHIN 1.9 Orbits, ORIENT 225D TO 227 D, ORIENT 25D TO 30D FROM 01, ORIENT 28D TO 45 D, POS TARG 16.34596, -7.20172 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names -ALF-PSA-C ------------------------------------------------------------------------------------------------------------------------------------