15461( 2) - 23-May-2018 13:53:48 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15461 Version: 2 Check-in Time: 23-May-2018 13:53:48 STScI Edit Number: 0 Title The detailed elemental composition of an exo-Pluto ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Carl Melis University of California - San Diego Y CoI: Dr. Patrick Dufour Universite de Montreal N CoI: Prof. Ben M. Zuckerman University of California - Los Angeles N CoI: Dr. Siyi Xu Gemini Observatory, Northern Operations N ------------------------------------------------------------------------------------ Abstract We have identified a new single, polluted, circumstellar disk-bearing white dwarf star first identified as a photometric white dwarf candidate in SDSS. SDSSJ0234-0406 is accreting extremely oxygen- and hydrogen-rich material that is otherwise depleted in all other rocky elements, suggesting that it is being polluted by a massive icy body. Similarities with the extrasolar Kuiper belt object-ingesting WD1425+540 suggest SDSSJ0234-0406 is being polluted by what could be an exo-Pluto analog. We propose COS FUV spectroscopic observations of SDSSJ0234-0406 that will allow us to confirm our interpretation and then obtain an exhaustive elemental composition for a Pluto-like body from another planetary system. These observations will address questions pertaining to the homogeneity of the formation and evolution of outer planetary systems and be a timely comparison to the New Horizons results for Pluto and eventually 2014 MU69. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our primary goal is to confirm the O-rich and rocky element-poor (Si, Fe) nature of SDSSJ0234-0406 and determine how much C, N, and S are present to place the origin of the accreted parent body. Our secondary goal is then to characterize additional elements. Modeling of absorption lines shows that the desired elements can be measured or sufficiently strongly constrained with observations in the 1130-1433 Angstrom range. We will perform medium spectral resolution ultraviolet spectroscopy with COS and the G130M grating to cover the 1130-1433 Angstrom range. In accordance with the COS2025 policies, we will only use two FP-POS positions (3 and 4). For the GALEX-measured FUV flux of SDSSJ0234-0406 (FUV AB magnitude of 17.27+/-0.035), we estimate how much time on source is necessary to obtain our desired S/N. It should be possible to obtain average S/N~15 in the 1130-1433 Angstrom wavelength range with total on-source exposure time of approximately 17, 000 seconds. These estimates are made using the COS ETC assuming standard background parameters and with a white dwarf spectral energy distribution matched to the parameters and flux level of our target. A signal-to-noise ratio of ~15 for the 1130-1433 Angstrom wavelength range will enable detection or tight limits on the abundances of O, Fe, Si, C, N, and S. Such a signal-to-noise ratio will also enable the detection or constraint of other 15461( 2) - 23-May-2018 13:53:48 - [ 2] elements (e.g., aluminum, phosphorus, chromium, manganese, or nickel). Our requested time estimates for COS are 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 7 orbits total for COS observations of SDSSJ0234-0406. Observations will be done in the TIME-TAG mode using TAG-FLASH wavelength calibration. SDSSJ0234-0406 is an ICRS object (SDSS position with less than 0.4" positional uncertainty), has measured GALEX UV fluxes, and is safe for the COS detectors in our desired setups. ------------------------------------------------------------------------------------ 15461( 2) - 23-May-2018 13:53:48 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ023415. STAR, DA, DB, DZ RA=02H34M15.5120S +/- 0.001", J2000 V = 16.3 +/- 0.01 m_FUV = 17.3, m_NUV = 51-040609.0 DEC=-04D06'9.06" +/- 0.001" 16.5 Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2008.9973 2.9756246170109844E-4 0.022393 0.0108609 ------------------------------------------------------------------------------------------------------------------------------------ 15461( 2) - 23-May-2018 13:53:48 - [ 4] Visit: 01 (SDSSJ0234COSFUV_3ORB) Visit Requirements: On Hold Comments: Additional Comments: COS/FUV observations of SDSSJ0234-0406 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 SDSSJ023415 COS/NUV ACQ/IMA PSA MIRRORB 1 32 S (32 .51-040609. GE S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ023415 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=4690, 1 2494 S .51-040609. G FLASH=YES (2494 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ023415 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=4690, 1 2916 S .51-040609. G FLASH=YES (2916 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ023415 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=4690, 1 2916 S .51-040609. G FLASH=YES (2916 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ023415.51-0406 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 09.0 GE SDSSJ023415.51-0406 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 09.0 G SDSSJ023415.51-0406 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 09.0 G SDSSJ023415.51-0406 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 09.0 G 15461( 2) - 23-May-2018 13:53:48 - [ 5] Visit: 02 (SDSSJ0234COSFUV_4ORB) Visit Requirements: On Hold Comments: Additional Comments: COS/FUV observations of SDSSJ0234-0406 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 SDSSJ023415 COS/NUV ACQ/IMA PSA MIRRORB 1 32 S (32 .51-040609. GE S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ023415 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=4690, 1 2494 S .51-040609. G FLASH=YES (2494 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ023415 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=4690, 1 2916 S .51-040609. G FLASH=YES (2916 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ023415 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=4690, 1 2916 S .51-040609. G FLASH=YES (2916 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ023415 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=4690, 1 2916 S .51-040609. G FLASH=YES (2916 S) 0 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ023415.51-0406 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 09.0 GE SDSSJ023415.51-0406 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 09.0 G SDSSJ023415.51-0406 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 09.0 G SDSSJ023415.51-0406 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 09.0 G SDSSJ023415.51-0406 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 09.0 G 15461( 2) - 23-May-2018 13:53:48 - [ 6] Summary Form for Proposal 15461 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=4690, FLASH=YES, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ023415.51-040609.0 ------------------------------------------------------------------------------------------------------------------------------------