17120( 6) - 31-Jul-2024 15:50:31 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17120 Version: 6 Check-in Time: 31-Jul-2024 15:50:31 STScI Edit Number: 3 Title Are all massive Kuiper belt objects built the same? ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Carl Melis University of California - San Diego Y CoI: Dr. Patrick Dufour Universite de Montreal N CoI: Dr. Alycia J. Weinberger Carnegie Institution of Washington N CoI: Dr. Beth L. Klein University of California - Los Angeles N CoI: Prof. Ben M. Zuckerman University of California - Los Angeles N CoI: Dr. Siyi Xu NOIRLab - Gemini North (HI) N ------------------------------------------------------------------------------------ Abstract We have identified GaiaJ0628-5054 as a single, polluted, white dwarf star that 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 hitherto unique extrasolar Kuiper belt object-ingesting WD1425+540 suggest GaiaJ0628-5054 is being polluted by what could be a rare second example of an extrasolar Kuiper belt object. We propose COS FUV spectroscopic observations of GaiaJ0628-5054 that will allow us to confirm our interpretation and then explore the range of rocky mass fractions for extrasolar Kuiper belt object analogs. These observations will have immediate value in assessing the validity of internal structure models for Pluto, Charon, and Arrokoth by providing a contrast of New Horizons interpretations for outer solar system bodies against what is observed in other planetary systems. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our primary goal is to further assess the O-rich and rocky element-poor (Si, Fe) nature of the polluted white dwarf star GaiaJ0628-5054 and determine how much C, N, and S are present to identify the origin of the accreted parent body. Our secondary goal is then to characterize additional elements that may enhance our understanding of the accreted material which appears to be a Kuiper belt object analog. Modeling of absorption lines shows that the desired elements can be measured or sufficiently strongly constrained with observations in the 1100-1350 Angstrom range. We will perform medium spectral resolution ultraviolet spectroscopy with COS and the G130M grating to cover the 1100-1350 Angstrom range. No GALEX-measured FUV flux exists for GaiaJ0628-5054; we instead estimate an FUV AB magnitude of 17.0 based off of spectral energy distribution fitting to optical and infrared data combined with an accurate atmospheric model that fits them. We estimate how much time on source is necessary to obtain our desired signal-to-noise with this estimated FUV magnitude and a small amount of interstellar reddening (consistent with its location in the Galaxy). It should be possible to obtain average signal-to-noise~20 in the 1100-1350 Angstrom 17120( 6) - 31-Jul-2024 15:50:31 - [ 2] wavelength range with total on-source exposure time of roughly 12, 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. 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 5 orbits total for COS observations of Gaia J0628-5054. Observations will be done in the TIME-TAG mode using TAG-FLASH wavelength calibration. The target white dwarf is an ICRS object (Gaia DR3 position with less than 0.4" positional uncertainty), has an estmated UV flux, and is safe for the COS detectors in our desired setups. ------------------------------------------------------------------------------------ 17120( 6) - 31-Jul-2024 15:50:31 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GAIA-EDR3-55 STAR, DB RA=06H28M27.1885S +/- 0.000258", J2000 V = 16.0 +/- 0.05 mFUV~17 507067141975 DEC=-50D54'47.32" +/- 0.000283" 81824 Reference Frame: ICRS Extended: NO Comments: Gaia DR3 Main astrometry. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 0.005673083905517535 0.056542 0.0137792 ------------------------------------------------------------------------------------------------------------------------------------ 17120( 6) - 31-Jul-2024 15:50:31 - [ 4] Visit: 01 (GaiaJ0628) Visit Requirements: On Hold Comments: Additional Comments: G130M grating observations of GaiaJ0628-5054. 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 GAIA-EDR3-5 COS/NUV ACQ/IMA PSA MIRRORB 1 20 S (20 55070671419 GE S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 2 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1226 S 55070671419 G BUFFER-TIME=3000 (1226 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 3 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1227 S 55070671419 G BUFFER-TIME=3000 (1227 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 4 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 5 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 6 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 7 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 8 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 9 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 10 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 17120( 6) - 31-Jul-2024 15:50:31 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GAIA-EDR3-555070671 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 4197581824 GE GAIA-EDR3-555070671 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 4197581824 G GAIA-EDR3-555070671 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 4197581824 G GAIA-EDR3-555070671 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 4197581824 G GAIA-EDR3-555070671 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 4197581824 G GAIA-EDR3-555070671 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 4197581824 G GAIA-EDR3-555070671 7 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 4197581824 G GAIA-EDR3-555070671 8 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 4197581824 G GAIA-EDR3-555070671 9 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 4197581824 G GAIA-EDR3-555070671 10 COS/FUV TIME-TA PSA G130M 1291 none none none none 5 N/A 4197581824 G GAIA-EDR3-555070671 11 COS/FUV TIME-TA PSA G130M 1291 none none none none 5 N/A 4197581824 G 17120( 6) - 31-Jul-2024 15:50:31 - [ 6] Visit: 51 (GaiaJ0628) Visit Requirements: On Hold Comments: Additional Comments: G130M grating observations of GaiaJ0628-5054. HOPR copy of visit 01. 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 GAIA-EDR3-5 COS/NUV ACQ/IMA PSA MIRRORB 1 20 S (20 55070671419 GE S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 2 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1226 S 55070671419 G BUFFER-TIME=3000 (1226 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 3 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1227 S 55070671419 G BUFFER-TIME=3000 (1227 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 4 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 5 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 6 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 7 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 8 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 9 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 10 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 17120( 6) - 31-Jul-2024 15:50:31 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1367 S 55070671419 G BUFFER-TIME=3000 (1367 S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ GAIA-EDR3-555070671 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 4197581824 GE GAIA-EDR3-555070671 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 4197581824 G GAIA-EDR3-555070671 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 4197581824 G GAIA-EDR3-555070671 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 4197581824 G GAIA-EDR3-555070671 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 4197581824 G GAIA-EDR3-555070671 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 4197581824 G GAIA-EDR3-555070671 7 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 4197581824 G GAIA-EDR3-555070671 8 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 4197581824 G GAIA-EDR3-555070671 9 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 4197581824 G GAIA-EDR3-555070671 10 COS/FUV TIME-TA PSA G130M 1291 none none none none 5 N/A 4197581824 G GAIA-EDR3-555070671 11 COS/FUV TIME-TA PSA G130M 1291 none none none none 5 N/A 4197581824 G 17120( 6) - 31-Jul-2024 15:50:31 - [ 8] Visit: 52 (GaiaJ0628) Visit Requirements: On Hold Comments: Additional Comments: G130M grating observations of GaiaJ0628-5054. Re-try to get last 2 orbits. 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 GAIA-EDR3-5 COS/NUV ACQ/IMA PSA MIRRORB 1 20 S (20 55070671419 GE S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 2 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1196 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1105 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1197 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1106 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1362 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1245 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1362 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1245 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 | ------------------------------------------------------------------------------------------------------------------------------------ GAIA-EDR3-555070671 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 4197581824 GE GAIA-EDR3-555070671 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 1105.0 S 4197581824 G GAIA-EDR3-555070671 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 1106.0 S 4197581824 G GAIA-EDR3-555070671 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 1245.0 S 4197581824 G GAIA-EDR3-555070671 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 1245.0 S 4197581824 G 17120( 6) - 31-Jul-2024 15:50:31 - [ 9] Visit: 53 (GaiaJ0628) Visit Requirements: On Hold Comments: Additional Comments: HOPR repeat of visit 52 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 GAIA-EDR3-5 COS/NUV ACQ/IMA PSA MIRRORB 1 20 S (20 55070671419 GE S) 7581824 ------------------------------------------------------------------------------------------------------------------------------------ 2 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1196 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1105 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1197 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1106 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=3, 1 1362 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1245 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 GAIA-EDR3-5 COS/FUV TIME-TA PSA G130M 1291 FLASH=YES, FP-POS=4, 1 1362 S 55070671419 G BUFFER-TIME=3000 see below 7581824 (1245 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 | ------------------------------------------------------------------------------------------------------------------------------------ GAIA-EDR3-555070671 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 4197581824 GE GAIA-EDR3-555070671 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 1105.0 S 4197581824 G GAIA-EDR3-555070671 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 1106.0 S 4197581824 G GAIA-EDR3-555070671 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 1245.0 S 4197581824 G GAIA-EDR3-555070671 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 1245.0 S 4197581824 G 17120( 6) - 31-Jul-2024 15:50:31 - [ 10] Summary Form for Proposal 17120 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=3000, FLASH=YES, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names GAIA-EDR3-5550706714197581824 ------------------------------------------------------------------------------------------------------------------------------------