14130( 4) - 14-Dec-2015 15:38:33 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14130 Version: 4 Check-in Time: 14-Dec-2015 15:38:33 STScI Edit Number: 0 Title Down the Tubes: Vetting the Apparent Water-rich Parent Body being Accreted by the White Dwarf GD 16 ------------------------------------------------------------------------------------ Type Cycle GO 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Carl Melis University of California - San Diego Y CoI: Dr. Patrick Dufour Universite de Montreal N ------------------------------------------------------------------------------------ Abstract How water is distributed in a planetary system critically affects the formation, evolution, and habitability of its constituent rocky bodies. White dwarf stars provide a unique method to probe the prevalence of water-rich rocky bodies outside of our Solar system and where they preferentially reside in a planetary system. However, as evidenced by the case of GD 362, some parent bodies that at first glance might appear to be water-rich can actually be quite water-scarce. At this time there are only a small number of plausibly water-rich rocky bodies that are being actively accreted by their host white dwarf star. Given such a sample size it is crucial to characterize each one in sufficient detail to remove interlopers like GD 362 that might otherwise affect future statistical analyses. In this proposal we seek to vet GD 16, a water-rich candidate yet to be observed with HST-COS that is the brightest remaining such target in the UV. ------------------------------------------------------------------------------------ Observations Description ------------------------ Detecting or constraining the absorption lines which inform our science goals requires observations in the 1800-2040 Ang range. Medium spectral resolution ultraviolet spectroscopy with COS and the G185M grating and a central wavelength of 1921 Ang will satisfy the observational requirements. Two FP-POS positions will be used to mitigate bad pixels and address fixed pattern noise. For the GALEX measured NUV flux of GD 16 (NUV AB magnitude of 16.22+/-0.02) it should be possible to obtain average S/N~20 in the 1800-2040 Ang wavelength range with a total on-source exposure time of ~12, 500 seconds. Signal-to-noise ratio of ~20 for the 1800-2040 Ang wavelength range will enable detection or tight limits on the abundances of silicon, carbon, and aluminum (the main science goals). Such a signal-to-noise ratio will also enable the detection or constraint of other elements (e.g., S, Ni, Co, Mn, and others). These estimates are made using the COS ETC assuming standard background parameters and with a GD 16 spectral energy distribution matched to precise optical photometry obtained by us for this proposal (note that this precise photometry limits any reddening to E(B-V)<~0.01). Our requested time estimate for COS is increased assuming 20 minutes of instrument overhead (including all acquisition and exposure overheads as suggested in the COS manual) per visit and 6 minutes of observatory overhead per orbit (spacecraft acquisition). In sum, we request 5 orbits for COS observations of GD 16. 14130( 4) - 14-Dec-2015 15:38:33 - [ 2] Observations will be done in the TIME-TAG mode using TAG-FLASH wavelength calibration. GD 16 is an ICRS object (SDSS position with less than 0.4" positional uncertainty), has a measured GALEX NUV flux, and is safe for the COS detectors in our desired setups. ------------------------------------------------------------------------------------ 14130( 4) - 14-Dec-2015 15:38:33 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 WOLF88 STAR, DA, DB, DZ RA=01H48M56.9390S +/- 0.001", J2000 V = 15.56 +/- 0.02 GALEX NUV ABmag = DEC=+19D02'26.56" +/- 0.001" 16.22+/-0.02 Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2009.0464 0.015797671211111843 -0.115 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14130( 4) - 14-Dec-2015 15:38:33 - [ 4] Visit: 01 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 WOLF88 COS/NUV ACQ/IMA PSA MIRRORB 1 30 S (30 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=3, BUFFER-TIME=1602, 1 1183 S G FLASH=YES (1183 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=4, BUFFER-TIME=1602, 1 1182 S G FLASH=YES (1182 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=3, BUFFER-TIME=1602, 1 1419 S G FLASH=YES (1419 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=4, BUFFER-TIME=1602, 1 1418 S G FLASH=YES (1418 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=3, BUFFER-TIME=1602, 1 1419 S G FLASH=YES (1419 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=4, BUFFER-TIME=1602, 1 1418 S G FLASH=YES (1418 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=3, BUFFER-TIME=1602, 1 1419 S G FLASH=YES (1419 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=4, BUFFER-TIME=1602, 1 1418 S G FLASH=YES (1418 S) ------------------------------------------------------------------------------------------------------------------------------------ 10 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=3, BUFFER-TIME=1602, 1 1419 S G FLASH=YES (1419 S) ------------------------------------------------------------------------------------------------------------------------------------ 11 WOLF88 COS/NUV TIME-TA PSA G185M 1921 FP-POS=4, BUFFER-TIME=1602, 1 1418 S G FLASH=YES (1418 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 | ------------------------------------------------------------------------------------------------------------------------------------ WOLF88 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A GE 14130( 4) - 14-Dec-2015 15:38:33 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ WOLF88 2 COS/NUV TIME-TA PSA G185M 1921 none none none none 1 N/A G WOLF88 3 COS/NUV TIME-TA PSA G185M 1921 none none none none 1 N/A G WOLF88 4 COS/NUV TIME-TA PSA G185M 1921 none none none none 2 N/A G WOLF88 5 COS/NUV TIME-TA PSA G185M 1921 none none none none 2 N/A G WOLF88 6 COS/NUV TIME-TA PSA G185M 1921 none none none none 3 N/A G WOLF88 7 COS/NUV TIME-TA PSA G185M 1921 none none none none 3 N/A G WOLF88 8 COS/NUV TIME-TA PSA G185M 1921 none none none none 4 N/A G WOLF88 9 COS/NUV TIME-TA PSA G185M 1921 none none none none 4 N/A G WOLF88 10 COS/NUV TIME-TA PSA G185M 1921 none none none none 5 N/A G WOLF88 11 COS/NUV TIME-TA PSA G185M 1921 none none none none 5 N/A G 14130( 4) - 14-Dec-2015 15:38:33 - [ 6] Summary Form for Proposal 14130 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1602, FLASH=YES, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G185M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names WOLF88 ------------------------------------------------------------------------------------------------------------------------------------