15898( 2) - 08-Jul-2019 15:05:06 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15898 Version: 2 Check-in Time: 08-Jul-2019 15:05:06 STScI Edit Number: 0 Title Planetary Pollution from the Habitable Zone of a White Dwarf ------------------------------------------------------------------------------------ Type Cycle GO 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Jay Farihi University College London Y CoI: Prof. Boris T. Gaensicke The University of Warwick N CoI: Dr. Seth Redfield Wesleyan University N CoI: Dr. Odette Fabiola Toloza The University of Warwick N Castillo ------------------------------------------------------------------------------------ Abstract On 24 Mar 2019, using high-cadence photometry, we discovered the second white dwarf system with planetary transit events. We have confirmed the period of numerous events to all be 25 h, which corresponds to a semimajor axis well within the habitable zone of the stellar remnant. The transit activity is essentially continuous at the few to several percent level, from blue to red wavelengths with no color dependence. Here we propose STIS near-ultraviolet spectroscopy to constrain the bulk chemistry of the planetary material accreted by the white dwarf. These observations will be sensitive to silicon and carbon, which cannot be accessed via ground-based observations, and are key components of both rocky and icy planetary materials. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of this program is to obtain high S/N near-ultraviolet spectroscopy of the white dwarf WD1054-226 to probe for metal absorption lines. The visit structure is straigh-forward: we acquire the target with the F28X50LP broad-band filter, and then switch to G230L time-tagged spectroscopy. ------------------------------------------------------------------------------------ 15898( 2) - 08-Jul-2019 15:05:06 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 WD1054-226 STAR, DA RA=10H56M38.6314S, J2000 V = 16.0 +/- 0.1 DEC=-22D52'56.08" Reference Frame: ICRS Extended: NO Comments: GALEX NUV= Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.005710661781372037 0.297948 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 15898( 2) - 08-Jul-2019 15:05:06 - [ 3] Visit: 01 (WD1054-226) 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 WD1054-226 STIS/CCD ACQ F28X50LP MIRROR 1 1 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 WD1054-226 STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=450 1 2175 S -MAMA G (2175 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WD1054-226 STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=450 1 2827 S -MAMA G (2827 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WD1054-226 STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=450 1 2804 S -MAMA G (2804 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 WD1054-226 STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=450 1 2804 S -MAMA G (2804 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 | ------------------------------------------------------------------------------------------------------------------------------------ WD1054-226 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A WD1054-226 2 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 1 N/A -MAMA G WD1054-226 3 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 2 N/A -MAMA G WD1054-226 4 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 3 N/A -MAMA G WD1054-226 5 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 4 N/A -MAMA G 15898( 2) - 08-Jul-2019 15:05:06 - [ 4] Summary Form for Proposal 15898 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.5, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=450 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names WD1054-226 ------------------------------------------------------------------------------------------------------------------------------------