17299( 5) - 11-Jun-2024 16:20:24 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17299 Version: 5 Check-in Time: 11-Jun-2024 16:20:24 STScI Edit Number: 1 Title A detailed far-ultraviolet study of the planetary debris accreting onto the magnetic white dwarf Feige 7 ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Boris T. Gaensicke The University of Warwick Y CoI: Prof. Stella Stopkowicz Universität des Saarlandes N CoI: Dr. John D. Landstreet The University of Western Ontario N ------------------------------------------------------------------------------------ Abstract Both photospheric metal pollution from the accretion of planetary debris, and strong (>MG) fields are, separately, detected among ~20% of all white dwarfs. However, the two features combined have so far only been observed in cool (<10000K) and old (>1Gyr) white dwarfs. The reason for this clustering is not well understood, but it may be related to how planet formation and the formation of magnetic fields depend on the white dwarf progenitor mass. We have identified Feige 7 as the first warm (~20000K) young (~200Myr) and strongly magnetic (~18MG) white dwarf that is actively accreting the debris of tidally disrupted planetesimals. The discovery of this system opens up the unprecedented opportunity to study atomic physics of C, Si, and potentially O, S, and Fe in an field that is orders of magnitude higher than what can be achieved in a laboratory on Earth. Modelling the Zeeman-split metal transitions, we will measure the photospheric abundances and infer the composition of the planetary debris. Comparison of these results with published composition studies will reveal if Feige 7 is distinct from the well-studied non-magnetic white dwarfs accreting planetary debris. Using spin-phase resolved spectroscopy, we will map both the magnetic field topology (from the Ly alpha Zeeman components) and the surface distribution of the accreted debris. This will represent the first detailed study of the accretion process, and inform our understanding of the lateral spreading of the planetary material accreted onto the white dwarf. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of these COS observations is to obtain phase-resolved COS/G130M FUV spectroscopy of the magnetic white dwarf Feige 77, fully sampling its spin period of 2.2h. The beat with the 96min HST orbit requires four consecutive orbits to achieve this goal. We split the observations into two visits, using each 1222A and 1291A as central wavelengths in one of them. Visit 1 (1291A) only uses FP-POS=3, 4 because of the COS 2025 policy, which generates a warning message. Visit 2 (1222A) uses FP-POS=1, 2, 3, 4. 17299( 5) - 11-Jun-2024 16:20:24 - [ 2] Apart from impacting the schedulability of this program, we do not foresee any negative effect should HST drop to a 2-gyro mode. This target (WDJ004345.98-100025.02 = Feige 7) was previously observed with COS/G130M as part of program 16642, the maximum flux level is ~1.5e-13erg/cm2/s/A. We use the same target acquisition as in the previous observation. https://archive.stsci.edu/cgi-bin/mastpreview?mission=hst&dataid=LEQC20010 ------------------------------------------------------------------------------------ 17299( 5) - 11-Jun-2024 16:20:24 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 FEIGE-7 STAR, DB RA=00H43M45.8278S +/- 0.0295", J2000 V = 14.5 +/- 0.05 DEC=-10D00'27.17" +/- 0.0172" Reference Frame: ICRS Extended: NO Comments: This target was previously observed with COS/G130M (exposure LEQC20010, https://archive.stsci.edu/cgi-bin/mastpreview?mission=hst&d ataid=LEQC20010), the maximum flux level is ~1.5e-13erg/cm2/s/A. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 -0.009858735263552344 -0.134876 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17299( 5) - 11-Jun-2024 16:20:24 - [ 4] Visit: 01 (Visit 1) Visit Requirements: On Hold Comments: Additional Comments: Only two FP-POS settings allowed for the 1291A central wavelength. 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 FEIGE-7 COS/FUV ACQ/PEA PSA G130M 1291 1 2 S (2 S) KXD ------------------------------------------------------------------------------------------------------------------------------------ 2 FEIGE-7 COS/FUV ACQ/PEA PSA G130M 1291 STEP-SIZE=0.9, NUM-POS=5, 1 2 S (2 S) KD CENTER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=3 1 2368 S G (2368 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=4 1 2693 S G (2693 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=3 1 2693 S G (2693 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=4 1 2693 S G (2693 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 | ------------------------------------------------------------------------------------------------------------------------------------ FEIGE-7 1 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KXD FEIGE-7 2 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KD FEIGE-7 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G FEIGE-7 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G FEIGE-7 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A G FEIGE-7 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A G 17299( 5) - 11-Jun-2024 16:20:24 - [ 5] Visit: 02 (Visit 2) Visit Requirements: On Hold Comments: Additional Comments: Only two FP-POS settings allowed for the 1291A central wavelength. 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 FEIGE-7 COS/FUV ACQ/PEA PSA G130M 1291 1 2 S (2 S) KXD ------------------------------------------------------------------------------------------------------------------------------------ 2 FEIGE-7 COS/FUV ACQ/PEA PSA G130M 1291 STEP-SIZE=0.9, NUM-POS=5, 1 2 S (2 S) KD CENTER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 FEIGE-7 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=195, FP-POS=1 1 2270 S G (2270 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 FEIGE-7 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=195, FP-POS=2 1 2693 S G (2693 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 FEIGE-7 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=195, FP-POS=3 1 2693 S G (2693 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 FEIGE-7 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=195, FP-POS=4 1 2693 S G (2693 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 | ------------------------------------------------------------------------------------------------------------------------------------ FEIGE-7 1 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KXD FEIGE-7 2 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KD FEIGE-7 3 COS/FUV TIME-TA PSA G130M 1222 none none none none 1 N/A G FEIGE-7 4 COS/FUV TIME-TA PSA G130M 1222 none none none none 2 N/A G FEIGE-7 5 COS/FUV TIME-TA PSA G130M 1222 none none none none 3 N/A G FEIGE-7 6 COS/FUV TIME-TA PSA G130M 1222 none none none none 4 N/A G 17299( 5) - 11-Jun-2024 16:20:24 - [ 6] Visit: 03 (Repeat of Visit 01) Visit Requirements: On Hold Comments: Additional Comments: Only two FP-POS settings allowed for the 1291A central wavelength. 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 FEIGE-7 COS/FUV ACQ/PEA PSA G130M 1291 1 2 S (2 S) KXD ------------------------------------------------------------------------------------------------------------------------------------ 2 FEIGE-7 COS/FUV ACQ/PEA PSA G130M 1291 STEP-SIZE=0.9, NUM-POS=5, 1 2 S (2 S) KD CENTER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 3 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=3 1 2305 S G see below (2247 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=4 1 2680 S G see below (2571 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=3 1 2680 S G see below (2571 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 FEIGE-7 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=195, FP-POS=4 1 2680 S G see below (2571 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 | ------------------------------------------------------------------------------------------------------------------------------------ FEIGE-7 1 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KXD FEIGE-7 2 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KD FEIGE-7 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2247.0 S G FEIGE-7 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2571.0 S G FEIGE-7 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 2571.0 S G FEIGE-7 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 2571.0 S G 17299( 5) - 11-Jun-2024 16:20:24 - [ 7] Summary Form for Proposal 17299 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAKD, ACQ/PEAKXD, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=195, CENTER=DEF, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, NUM-POS=5, STEP-SIZE=0.9 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M ------------------------------------------------------------------------------------------------------------------------------------ Target Names FEIGE-7 ------------------------------------------------------------------------------------------------------------------------------------