15152( 5) - 10-Dec-2018 12:16:48 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15152 Version: 5 Check-in Time: 10-Dec-2018 12:16:48 STScI Edit Number: 3 Title Finally, the Progenitor of the Type Ib iPTF13bvn ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Schuyler D. Van Dyk California Institute of Technology Y CoI: Dr. Gaston Folatelli Universidad Nacional de La Plata (UNLP) N CoI: Dr. Melina C. Bersten Universidad Nacional de La Plata (UNLP) N CoI: Prof. Alex V. Filippenko University of California - Berkeley N CoI: Dr. Mario Hamuy Universidad de Chile N CoI: Prof. Keiichi Maeda Kyoto University N CoI: Prof. Ken'ichi Nomoto Institute for Physics and Mathematics of N the Universe CoI: Dr. Giuliano Pignata Universidad Andres Bello N CoI: Prof. Robert M. Quimby San Diego State University N CoI: Dr. WeiKang Zheng University of California - Berkeley N CoI: Dr. Hanindyo Kuncarayakti University of Turku N ------------------------------------------------------------------------------------ Abstract Supernovae (SNe) are among the most powerful events in the Universe and have a profound influence on galaxy evolution. Whereas we have been able to identify the luminous red supergiant progenitor stars of the most common core-collapse explosions, the hydrogen-rich Type II, the progenitors of hydrogen-poor Type Ib and Type Ic have been far more elusive. To strip away a SN Ib/c progenitor's outer layers, theoretical models with either (a) a highly-massive star with prodigious winds during the Wolf-Rayet phase or (b) a somewhat lower-mass star in a close, mass-exchange binary system have been proposed. One example exists so far of a progenitor identification, for the SN Ib iPTF13bvn in NGC 5806. Both models have been invoked to explain this event, although most evidence to date points toward the binary model. Our combined team observed this SN with WFC3 in Cycle 22, about 2 years after explosion, to investigate whether the progenitor had disappeared. As a result, we were able to report that indeed it had. We also attempted to better characterize the nature of the progenitor by subtracting our images from the pre-explosion HST data. Unfortunately, the old SN was apparently still conspicuously present. We therefore propose to reimage the SN site, when the SN should then be well below detectability, to produce high-quality templates of the host galaxy for subtraction. We can then finally fully reveal the progenitor and understand its true nature. iPTF13bvn is one of the most important historical SNe and will most probably be the best available case of a SN Ib progenitor for HST's remaining lifetime. It is imperative to understand the nature of this SN and its progenitor object. ------------------------------------------------------------------------------------ Observations Description ------------------------ We are reimaging, once again, the site of iPTF13bvn in NGC 5806, to better establish the characteristics of its progenitor. We know now that the object identified by Cao et al. (2013) is indeed the progenitor. However, we need to 15152( 5) - 10-Dec-2018 12:16:48 - [ 2] look at the site again, when the SN itself has finally faded below detectability. We have simply duplicated the observing schemes from GO-13684 (PI: Van Dyk) at F438W (B) and F555W (V ) and from GO-13822 (PI: Folatelli) at F814W (I), in order to go at least as deep as those previous observations. The new observations at F438W and F555W consist of line-dithered 1422-s exposures in each orbit (except for the first orbit, which consists of a 1365 s and a 1368 s exposure, to allow for guide star acquisition overhead) with WFC3/UVIS, and a trio of dithered 775-s exposures at F814W with ACS/WFC. If the remaining SN light continues to be powered by radioactive positron trapping, with a later contribution from 44Ti decay, then the SN should be at ~31--32 mag during Cycle 25. We will be able to perform a far better subtraction than from the pre-SN images from 2005 and, thus, far more significantly constrain the actual brightness and color of the progenitor. We will compare our measurements to current progenitor models for SNe Ib. The primary visibility window in Cycle 25 is 07 June to 17 Sep 2018. These observations can certainly also be scheduled during Cycle 26. Since the SN will have effectively faded, it should not make little difference if there is a time gap between the WFC3 and ACS visits. ------------------------------------------------------------------------------------ 15152( 5) - 10-Dec-2018 12:16:48 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 IPTF-13BVN EXT-STAR, SUPERNOVA, RA=15H00M0.1520S, J2000 V = 31 +/- 1 SUPERNOVA TYPE IB DEC=+01D52'53.17" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 15152( 5) - 10-Dec-2018 12:16:48 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 3.034 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.29 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15152( 5) - 10-Dec-2018 12:16:48 - [ 5] Visit: 01 (ACS-F814W) 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 IPTF-13BVN ACS/WFC ACCUM WFC F814W 1 775 S PATTERN 1 1 (2325 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 | ------------------------------------------------------------------------------------------------------------------------------------ IPTF-13BVN 1 ACS/WFC ACCUM WFC F814W 1 none none none 1 N/A IPTF-13BVN 1 ACS/WFC ACCUM WFC F814W 2 none none none 1 N/A IPTF-13BVN 1 ACS/WFC ACCUM WFC F814W 3 none none none 1 N/A 15152( 5) - 10-Dec-2018 12:16:48 - [ 6] Visit: 02 (WFC3-F438W-F555W) 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 IPTF-13BVN WFC3/UVI ACCUM UVIS F555W 1 1422 S PATTERN 3 1 S see below (5437 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 IPTF-13BVN WFC3/UVI ACCUM UVIS F438W FLASH=1 1 1300 S PATTERN 3 2 S see below (5408 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 | ------------------------------------------------------------------------------------------------------------------------------------ IPTF-13BVN 1 WFC3/UVI ACCUM UVIS F555W 1 none none none 1 1365.0 S S IPTF-13BVN 1 WFC3/UVI ACCUM UVIS F555W 2 none none none 1 1368.0 S S IPTF-13BVN 1 WFC3/UVI ACCUM UVIS F555W 3 none none none 2 1352.0 S S IPTF-13BVN 1 WFC3/UVI ACCUM UVIS F555W 4 none none none 2 1352.0 S S IPTF-13BVN 2 WFC3/UVI ACCUM UVIS F438W 1 none none none 3 1352.0 S S IPTF-13BVN 2 WFC3/UVI ACCUM UVIS F438W 2 none none none 3 1352.0 S S IPTF-13BVN 2 WFC3/UVI ACCUM UVIS F438W 3 none none none 4 1352.0 S S IPTF-13BVN 2 WFC3/UVI ACCUM UVIS F438W 4 none none none 4 1352.0 S S 15152( 5) - 10-Dec-2018 12:16:48 - [ 7] Summary Form for Proposal 15152 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS, WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=1 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 3 1, PATTERN 3 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F438W, F555W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names IPTF-13BVN ------------------------------------------------------------------------------------------------------------------------------------