17723( 3) - 29-Aug-2025 03:26:27 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17723 Version: 3 Check-in Time: 29-Aug-2025 03:26:27 STScI Edit Number: 2 Title The first UV investigation of a massive stripped-envelope core-collapse progenitor at high metallicity: The WO star WR 102 ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Roel Lefever Astronomisches Rechen-Institut Heidelberg Y CoI: Dr. Andreas Sander Astronomisches Rechen-Institut Heidelberg N CoI: Dr. Jorick Vink Armagh Observatory and Planetarium N CoI: Dr. Wolf-Rainer Hamann Universitat Potsdam N CoI: Prof. Lidia Oskinova Universitat Potsdam N CoI: Dr. Varsha Ramachandran Universitat Heidelberg N CoI: Dr. Tomer Shenar Tel Aviv University - Wise Observatory N CoI: Erin Rose Higgins Armagh Observatory and Planetarium N CoI: Dr. Helge Todt Universitat Potsdam N CoI: Dr. Daniel Pauli Institute of Astronomy, KU Leuven N CoI: Dr. Philip Louis Massey Lowell Observatory N CoI: Matheus Bernini Peron Astronomisches Rechen-Institut Heidelberg N CoI: Elisa Clara Schosser Universitat Heidelberg N CoI: Mr. Joris Josiek Universitat Heidelberg N CoI: Dr. Gemma Gonzalez-Tora Astronomisches Rechen-Institut Heidelberg N ------------------------------------------------------------------------------------ Abstract The WO-type Wolf-Rayet stars of the oxygen sequence represent the final stage in the life of a massive star. These stars offer a unique window to the evolutionary stages right before going supernovae and collapsing into black holes (BHs). A WO star is dominated by a strong stellar wind that further strips its outer layers. This large mass loss ultimately determines how much mass is left for a BH to form. Given the discrepancy between observed BH masses and final masses from stellar evolution, determining the wind structure and mass-loss rate is paramount. Moreover, the evolution of these stars and their winds is poorly constrained: whether some WO stars will undergo a stripped-envelope supernova (SNIbc) is currently under debate. Optical analyses exist but cannot reveal the whole picture: mayor wind drivers and nucleosynthesis indicators can only be observed in the UV. Yet, UV spectra of WO stars at Galactic metallicities are absent. Looking at the most evolved WO star in the Milky Way, WR 102, we propose to obtain pioneering UV data to understand massive, stripped core-collapse progenitors at high metallicity and shed light on the SNIbc puzzle. Being highly evolved and stripped objects, the abundances of WO stars also yield a unique insight into the highly uncertain C-O nuclear reaction rate. Using stellar atmosphere models with an inherent solution of the hydrodynamic equation, we will further be able to obtain consistent density stratifications for our targets and get a unique handle on the so far uncertain stellar mass. Thereby, we will be able to provide a crucial testbed for the circumstellar emvironment of highly stripped stars undergoing core collapse. ------------------------------------------------------------------------------------ Observations Description 17723( 3) - 29-Aug-2025 03:26:27 - [ 2] ------------------------ The spectra of WR102 (V-V3893-SGR) will be obtained using the COS G140L (800 Angstroem) grating. As this specific grating has a pass band of 913-1940 Angstroem, the FUV range of the spectrum is well covered and without gaps. The FUV range is crucial for our target star since prominent wind features in the spectra, along with P Cygni profiles, are paramount to break parameter ambiguity resulting often from optical spectra of Wolf-Rayet stars. More specifically, expectedly strong lines like O VI 1371 Angstroem and CIV 1548-50 Angstroem are of particular importance for wind parameter and abundance determinations in our analyses. As WR102 is quite reddened, with an E(B-V) = 1.26 (Tramper et al. 2015), the FUV regime of this star requires more exposure time than its visual magnitude of 14.20 suggests. Hence, the total of 12 orbits is necessary for our requirements. A total science exposure time of 30, 078s ensures an SNR of 13.3 at 1480 Angstroem, this latter value being chosen to avoid the SNR estimate being heavily influenced by strong spectral lines. In addition, this science exposure time ensures an SNR between 10 and 11 around wavelengths around 1320 Angstroem. ------------------------------------------------------------------------------------ 17723( 3) - 29-Aug-2025 03:26:27 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 V-V3893-SGR STAR, WOLF RAYET RA=17H45M47.5405S +/- 0.0192", J2000 V = 14.2 DEC=-26D10'26.78" +/- 0.0147" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. SIMBAD listed proper motion for this target. When retrieving targets with PM from SIMBAD, APT requests the coordinates be calculated with an epoch of the year 2000. Do not modify this epoch. Always review coordinates using the Target Confirmation tool, which graphically displays the PM. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 5.6455764155085035E-5 -5.9999999999999995E-5 0.0003241 ------------------------------------------------------------------------------------------------------------------------------------ 17723( 3) - 29-Aug-2025 03:26:27 - [ 4] Visit: 01 (visit1) 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 V-V3893-SGR COS/NUV ACQ/IMA PSA MIRRORA 1 20 S (20 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=1 1 2262 S G (2262 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=2 1 2588 S G (2588 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=3 1 2588 S G (2588 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=4 1 2588 S G (2588 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 | ------------------------------------------------------------------------------------------------------------------------------------ V-V3893-SGR 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE V-V3893-SGR 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 N/A G V-V3893-SGR 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 N/A G V-V3893-SGR 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 N/A G V-V3893-SGR 5 COS/FUV TIME-TA PSA G140L 800 none none none none 4 N/A G 17723( 3) - 29-Aug-2025 03:26:27 - [ 5] Visit: 02 (visit2) 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 V-V3893-SGR COS/NUV ACQ/IMA PSA MIRRORA 1 20 S (20 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=1 1 2262 S G (2262 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=2 1 2588 S G (2588 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=3 1 2588 S G (2588 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=4 1 2588 S G (2588 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 | ------------------------------------------------------------------------------------------------------------------------------------ V-V3893-SGR 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE V-V3893-SGR 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 N/A G V-V3893-SGR 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 N/A G V-V3893-SGR 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 N/A G V-V3893-SGR 5 COS/FUV TIME-TA PSA G140L 800 none none none none 4 N/A G 17723( 3) - 29-Aug-2025 03:26:27 - [ 6] Visit: 03 (visit3) 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 V-V3893-SGR COS/NUV ACQ/IMA PSA MIRRORA 1 20 S (20 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=1 1 2262 S G (2262 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=2 1 2588 S G (2588 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=3 1 2588 S G (2588 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=4 1 2588 S G (2588 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 | ------------------------------------------------------------------------------------------------------------------------------------ V-V3893-SGR 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE V-V3893-SGR 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 N/A G V-V3893-SGR 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 N/A G V-V3893-SGR 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 N/A G V-V3893-SGR 5 COS/FUV TIME-TA PSA G140L 800 none none none none 4 N/A G 17723( 3) - 29-Aug-2025 03:26:27 - [ 7] Visit: 10 (visit1) 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 V-V3893-SGR COS/NUV ACQ/IMA PSA MIRRORA 1 20 S (20 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=3 1 2588 S G see below (2200 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=4 1 2588 S G see below (2539 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 | ------------------------------------------------------------------------------------------------------------------------------------ V-V3893-SGR 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE V-V3893-SGR 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 2200.0 S G V-V3893-SGR 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 2539.0 S G 17723( 3) - 29-Aug-2025 03:26:27 - [ 8] Visit: 20 (visit2) 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 V-V3893-SGR COS/NUV ACQ/IMA PSA MIRRORA 1 20 S (20 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=1 1 2262 S G see below (2214 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=2 1 2588 S G see below (2539 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=3 1 2588 S G see below (2539 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 V-V3893-SGR COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=9403, FP-POS=4 1 2588 S G see below (2539 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 | ------------------------------------------------------------------------------------------------------------------------------------ V-V3893-SGR 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE V-V3893-SGR 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 2214.0 S G V-V3893-SGR 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 2539.0 S G V-V3893-SGR 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 2539.0 S G V-V3893-SGR 5 COS/FUV TIME-TA PSA G140L 800 none none none none 4 2539.0 S G 17723( 3) - 29-Aug-2025 03:26:27 - [ 9] Summary Form for Proposal 17723 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=9403, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names V-V3893-SGR ------------------------------------------------------------------------------------------------------------------------------------