14813( 3) - 18-Jul-2016 11:50:22 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14813 Version: 3 Check-in Time: 18-Jul-2016 11:50:22 STScI Edit Number: 2 Title A highly dynamical debris disc in an evolved planetary system ------------------------------------------------------------------------------------ Type Cycle GO 24 ------------------------------------------------------------------------------------ Investigators Contact? PI: Mr. Christopher James Manser The University of Warwick Y CoI: Prof. Boris T. Gaensicke The University of Warwick N CoI: Prof. Detlev G. Koester Universitat Kiel N CoI: Prof. Tom R. Marsh The University of Warwick N CoI: Dr. Dimitri Veras The University of Warwick N ------------------------------------------------------------------------------------ Abstract Our HST/COS survey for the photospheric pollution by planetary debris undisputably demonstrates that at least 25% of white dwarfs host an evolved planetary system. The debris discs holding the material that accretes onto the white dwarf are produced by the tidal disruption of asteroids, and are observed in nearly 40 systems by infrared excess emission from micron-sized dust. In a small number of cases, we have also detected double-peaked Ca II 860 nm emission lines from a metal-rich gaseous disc in addition to photospheric pollution and circumstellar dust. Our ground-based monitoring of the brightest of these systems, SDSS J1228+1040, over the last eleven years shows a dramatic morphological change in the emission line profiles on the time-scale of years. The evolution of the line profiles is consistent with the precession of an eccentric disc on a period of ~25 years, indicating a recent dynamical interaction within the underlying dust disc. This could either be related to the initial circularisation of the disc, or a secondary impact onto an existing disc. We expect that the accretion rate onto the white dwarf varies on the same timescale as the Ca II emission lines, and there is the tantalising possibility to detect changes in the bulk abundances, if the impact of a planetesimal with a different bulk abundance stirred up the disc. We request a small amount of COS time to monitor the debris abundances over the next three HST Cycles to test this hypothesis, and bolster our understanding of the late evolution of planetary systems. ------------------------------------------------------------------------------------ Observations Description ------------------------ We request the 3 visits to be spaced as equally apart as possible over the 3 years, as we require the multiple observations for time-resolved spectroscopy of the absorption lines present in the UV. ------------------------------------------------------------------------------------ 14813( 3) - 18-Jul-2016 11:50:22 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ1228+10 STAR, DA, DISK, RA=12H28M59.9350S +/- 0.1", J2000 V = 16.2 GALEX FUV=15.62 +/- 0.02 GALEX 40 EXTRA-SOLAR PLANETARY DEC=+10D40'33.25" +/- 0.1" NUV=15.85 +/- 0.02 SYSTEM Reference Frame: ICRS Extended: NO Comments: SDSSJ1228+1040 has been observed three times with COS (HST programs 11561, 12906, and the first of this monitoring proposal in March 2016) - no bright object limit concerns. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.0024897624718717283 -0.026699999999999998 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14813( 3) - 18-Jul-2016 11:50:22 - [ 3] Visit: 01 (SDSS1228+1040 epoch 2) 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ1228+1 COS/NUV ACQ/IMA PSA MIRRORB 1 14 S (14 040 GE S) Comments: Target acquisition based on an uploaded WD model spectrum that has been scale to the COS data from a previous observation. ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ1228+1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1119, FP-POS=1 1 1222 S 040 G (1222 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ1228+1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1119, FP-POS=2 1 1221 S 040 G (1221 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ1228+1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=651, FP-POS=3 1 1408 S 040 G (1408 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ1228+1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=651, FP-POS=4 1 1409 S 040 G (1409 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ1228+1040 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE SDSSJ1228+1040 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G SDSSJ1228+1040 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G SDSSJ1228+1040 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G SDSSJ1228+1040 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G 14813( 3) - 18-Jul-2016 11:50:22 - [ 4] Summary Form for Proposal 14813 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1119, BUFFER-TIME=651, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ1228+1040 ------------------------------------------------------------------------------------------------------------------------------------