17441( 5) - 21-Jan-2025 17:47:15 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17441 Version: 5 Check-in Time: 21-Jan-2025 17:47:15 STScI Edit Number: 1 Title UV spectroscopy of runaways from thermonuclear supernovae ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Kareem El-Badry California Institute of Technology Y CoI: Dr. Ken Shen University of California - Berkeley N CoI: Prof. Boris T. Gaensicke University of Warwick N ------------------------------------------------------------------------------------ Abstract We propose COS FUV spectroscopy of four newly-discovered hypervelocity white dwarfs that are runaways from double white dwarf binaries in which one component exploded in a type Ia supernova. Our targets have radial velocities ranging from 1100 to 2300 km/s -- the fastest stellar radial velocities ever measured. They are hot (20, 000-140, 000 K) and bright in the UV. The primary goal is measurement of their abundance patterns, particularly the abundances of Fe, Si, Mg, and Mn. The surfaces of these stars are predicted to be heavily polluted with supernova ejecta. Abundance measurements will constrain the yields of the supernovae from which these stars were born and the masses of the exploded white dwarfs, both clarifying their formation histories and informing models for their thermal evolution. Optical spectroscopy has shown that their atmospheres consist mostly of carbon and oxygen, but the abundances of most metals can only be measured in the UV at these temperatures. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain 11 orbits of HST/COS medium-resolution FUV spectroscopy of four hot, inflated WDs. The three brightest objects, with FUV = 17.9, 18.0, and 18.2 mag, will be observed for two orbits each, while the faintest target, with FUV = 19.5 mag, will be observed for 5 orbits. The FUV magnitudes are measured from GALEX for two targets and estimated based on the effective temperature and optical SED for the other two. The extinction is low ($E(B-V) < 0.2$), and the expected FUV magnitudes are well-constrained. None of the targets have nearby bright UV sources that would risk damaging the detector. We will acquire each target using the NUV channel with an ACQ/IMAG sequence, and then switch to the FUV channel, using the G140L grating with the 1105 AA central wavelength, spanning 1130-2000 AA. Detailed modeling of the photospheric abundances (particularly Fe, Si, Mg, and Mn), requires a signal-to-noise ratio ~30. Using the COS ETC with model spectra generated for our targets based on their optical spectra and broadband SEDs, and accounting for the targets' individual visibility windows and instrumental overheads, we find that we can achieve SNR = 26-33 at 1300 AA in one orbit each for the 3 brightest targets, and SNR = 20 in 5 orbits for the faintest target. ------------------------------------------------------------------------------------ 17441( 5) - 21-Jan-2025 17:47:15 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 J1235-3752 STAR, SDO RA=12H35M31.8000S +/- 0.01", J2000 V = 19.0 +/- 0.1 NUV = 18.89, FUV = DEC=-37D52'35.53" +/- 0.01" 19.49 Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 -0.0017571181276592712 0.09287213882 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 J0927-6335 STAR, SDO RA=09H27M42.6800S +/- 0.01", J2000 V = 19.3 +/- 0.1 NUV = 18.3, FUV = 18.0 DEC=-63D35'40.33" +/- 0.01" Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 -0.005131311719612245 0.04293 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 J0546+0836 STAR, SDO RA=05H46M17.6000S +/- 0.01", J2000 V = 19.0 +/- 0.1 NUV = 18.4, FUV = 18.2 DEC=+08D36'6.65" +/- 0.01" Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 -8.434879237248091E-4 -0.07503 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4 J1332-3541 STAR, SDO RA=13H32M57.9800S +/- 0.01", J2000 V = 19.4 +/- 0.1 NUV = 18.23, FUV = DEC=-35D41'10.68" +/- 0.01" 17.94 Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 -0.011425433173360113 0.06937 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17441( 5) - 21-Jan-2025 17:47:15 - [ 3] Visit: 01 (J0927) 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 J0927-6335 COS/NUV ACQ/IMA PSA MIRRORA 1 10 S (10 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J0927-6335 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1145, FP-POS=1 1 1255 S G (1255 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J0927-6335 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1217, FP-POS=2 1 1256 S G (1256 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J0927-6335 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1312, FP-POS=3 1 1422 S G (1422 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 J0927-6335 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1384, FP-POS=4 1 1423 S G (1423 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 | ------------------------------------------------------------------------------------------------------------------------------------ J0927-6335 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J0927-6335 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A G J0927-6335 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A G J0927-6335 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A G J0927-6335 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A G 17441( 5) - 21-Jan-2025 17:47:15 - [ 4] Visit: 02 (J0546) 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 J0546+0836 COS/NUV ACQ/IMA PSA MIRRORA 1 10 S (10 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J0546+0836 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1010, FP-POS=1 1 1120 S G see below (1042 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J0546+0836 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1082, FP-POS=2 1 1120 S G see below (1042 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J0546+0836 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1177, FP-POS=3 1 1287 S G see below (1175 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 J0546+0836 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1249, FP-POS=4 1 1287 S G see below (1175 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 | ------------------------------------------------------------------------------------------------------------------------------------ J0546+0836 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J0546+0836 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 1042.0 S G J0546+0836 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 1042.0 S G J0546+0836 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 1175.0 S G J0546+0836 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 1175.0 S G 17441( 5) - 21-Jan-2025 17:47:15 - [ 5] Visit: 03 (J1332) 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 J1332-3541 COS/NUV ACQ/IMA PSA MIRRORA 1 10 S (10 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1332-3541 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1032, FP-POS=1 1 1142 S G see below (1056 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1332-3541 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1100, FP-POS=2 1 1142 S G see below (1056 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1332-3541 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1190, FP-POS=3 1 1309 S G see below (1202 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 J1332-3541 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1190, FP-POS=4 1 1309 S G see below (1202 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1332-3541 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J1332-3541 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 1056.0 S G J1332-3541 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 1056.0 S G J1332-3541 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 1202.0 S G J1332-3541 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 1202.0 S G 17441( 5) - 21-Jan-2025 17:47:15 - [ 6] Visit: 04 (J1235) 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 J1235-3752 COS/NUV ACQ/IMA PSA MIRRORA 1 13 S (13 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1235-3752 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=2273, FP-POS=1 1 2383 S G see below (2306 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1235-3752 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=2723, FP-POS=2 1 2723 S G see below (2595 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 J1235-3752 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=2723, FP-POS=3 1 2723 S G see below (2595 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 J1235-3752 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=2723, FP-POS=4 1 2723 S G see below (2595 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 J1235-3752 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=477, FP-POS=ALL 1 587 S G see below (1976 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1235-3752 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J1235-3752 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 2306.0 S G J1235-3752 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 2595.0 S G J1235-3752 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 3 2595.0 S G J1235-3752 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 4 2595.0 S G J1235-3752 6 COS/FUV TIME-TA PSA G140L 1105 none none none 1 5 494.0 S G 17441( 5) - 21-Jan-2025 17:47:15 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1235-3752 6 COS/FUV TIME-TA PSA G140L 1105 none none none 2 5 494.0 S G J1235-3752 6 COS/FUV TIME-TA PSA G140L 1105 none none none 3 5 494.0 S G J1235-3752 6 COS/FUV TIME-TA PSA G140L 1105 none none none 4 5 494.0 S G 17441( 5) - 21-Jan-2025 17:47:15 - [ 8] Visit: 05 (J1332) 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 J1332-3541 COS/NUV ACQ/IMA PSA MIRRORA 1 10 S (10 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 J1332-3541 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1190, FP-POS=3 1 1309 S G see below (1065 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 J1332-3541 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=1190, FP-POS=4 1 1309 S G see below (1065 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 | ------------------------------------------------------------------------------------------------------------------------------------ J1332-3541 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE J1332-3541 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 1065.0 S G J1332-3541 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 1065.0 S G 17441( 5) - 21-Jan-2025 17:47:15 - [ 9] Summary Form for Proposal 17441 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1010, BUFFER-TIME=1032, BUFFER-TIME=1082, BUFFER-TIME=1100, BUFFER-TIME=1145, BUFFER-TIME=1177, BUFFER-TIME=1190, BUFFER-TIME=1217, BUFFER-TIME=1249, BUFFER-TIME=1312, BUFFER-TIME=1384, BUFFER-TIME=2273, BUFFER-TIME=2723, BUFFER-TIME=477, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, FP-POS=ALL ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names J0546+0836, J0927-6335, J1235-3752, J1332-3541 ------------------------------------------------------------------------------------------------------------------------------------