16508( 5) - 17-May-2021 12:48:27 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16508 Version: 5 Check-in Time: 17-May-2021 12:48:27 STScI Edit Number: 2 Title Confirming a Failed Supernova Candidate in M51 ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Jacob Jencson University of Arizona Y CoI: Prof. David J. Sand University of Arizona N CoI: Prof. Jay Strader Michigan State University N CoI: Dr. Nathan Smith University of Arizona N CoI: Dr. Jennifer Andrews NOIRLab - Gemini North (HI) N CoI: Jeniveve Pearson University of Arizona N CoI: Dr. Stefano Valenti University of California - Davis N ------------------------------------------------------------------------------------ Abstract We request three orbits of ACS (F606W, F814W) and WFC3 IR (F110W, F160W) imaging at the location of a red supergiant star in M51 that has vanished, potentially as a 'failed supernova' that directly collapsed into a black hole. There is mounting evidence, both observational and theoretical, that 10-30% of core collapses do not yield a supernova explosion, but only one viable candidate for such a 'failed supernova' event has been observed thus far. Here, we have discovered a new, strong candidate for the disappearance of a luminous star in M51 which has been detected dozens of times with HST through late 2017. The star had the characteristics of a 25-30 M_sun red supergiant before it faded from view (>2.0 mag) in 2019 in a crowded region of a spiral arm. Deep HST multi-band imaging in the next few months will confirm the nature of the vanished star and rule out possible alternatives, such as a dust-obscured star. These observations will also constrain any fading remnant emission that may be associated with fallback accretion or an associated dust shell; depending on the results, this will be a prime target for further HST and JWST monitoring in future cycles. HST is the only currently available facility with the resolution and sensitivity, especially in the near-IR, necessary to perform this test. Confirmation of a second strong case for a 'failed supernova' will have broad consequences, not only for verifying this channel of stellar death, but for our understanding of stellar remnants, chemical enrichment, and ultimately models of black hole formation. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our primary science goal is to determine the nature of the fading source M51-DS1. To accomplish this we require three orbits total to observe in the optical (F606W, F814W) and near-infrared (F110W, F160W). The optical data (two orbits) will be with ACS/WFC, and the near-infrared (one orbit) with WFC3/IR. We split up our observations into three separate visits of one orbit each. For both the ACS and WFC3 observations, we use a standard four-point dither box for each orbit, with sub-pixel dithers in order to get closer to the native 16508( 5) - 17-May-2021 12:48:27 - [ 2] resolution of ACS. ------------------------------------------------------------------------------------ 16508( 5) - 17-May-2021 12:48:27 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M51DS1 STAR, CIRCUMSTELLAR RA=13H29M56.1600S, J2000 V = 24.0 MATTER, SUPERGIANT O DEC=+47D11'47.83" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 16508( 5) - 17-May-2021 12:48:27 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.262 Line_Spacing 0.192 Coordinate_Frame POS-TARG Pattern_Orient 18.39 Angle_Between_Sides 68.14 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.605 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16508( 5) - 17-May-2021 12:48:27 - [ 5] Visit: 01 (M51DS1_F606W) 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 M51DS1 ACS/WFC ACCUM WFC1 F606W 1 400 S PATTERN 1 1 see below (2208 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 | ------------------------------------------------------------------------------------------------------------------------------------ M51DS1 1 ACS/WFC ACCUM WFC1 F606W 1 none none none 1 552.0 S M51DS1 1 ACS/WFC ACCUM WFC1 F606W 2 none none none 1 552.0 S M51DS1 1 ACS/WFC ACCUM WFC1 F606W 3 none none none 1 552.0 S M51DS1 1 ACS/WFC ACCUM WFC1 F606W 4 none none none 1 552.0 S 16508( 5) - 17-May-2021 12:48:27 - [ 6] Visit: 02 (M51DS1_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 M51DS1 ACS/WFC ACCUM WFC1 F814W 1 400 S PATTERN 1 1 see below (2208 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 | ------------------------------------------------------------------------------------------------------------------------------------ M51DS1 1 ACS/WFC ACCUM WFC1 F814W 1 none none none 1 552.0 S M51DS1 1 ACS/WFC ACCUM WFC1 F814W 2 none none none 1 552.0 S M51DS1 1 ACS/WFC ACCUM WFC1 F814W 3 none none none 1 552.0 S M51DS1 1 ACS/WFC ACCUM WFC1 F814W 4 none none none 1 552.0 S 16508( 5) - 17-May-2021 12:48:27 - [ 7] Visit: 04 (M51DS1_IR) 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 M51DS1 WFC3/IR MULTIAC IR F110W NSAMP=9, SAMP-SEQ=STEP100 1 DEF PATTERN 3 1 CUM (1196.925 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 M51DS1 WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=STEP100 1 DEF PATTERN 3 2 CUM (1196.925 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 | ------------------------------------------------------------------------------------------------------------------------------------ M51DS1 1 WFC3/IR MULTIAC IR F110W 1 none none none 1 N/A CUM M51DS1 1 WFC3/IR MULTIAC IR F110W 2 none none none 1 N/A CUM M51DS1 1 WFC3/IR MULTIAC IR F110W 3 none none none 1 N/A CUM M51DS1 1 WFC3/IR MULTIAC IR F110W 4 none none none 1 N/A CUM M51DS1 2 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM M51DS1 2 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM M51DS1 2 WFC3/IR MULTIAC IR F160W 3 none none none 1 N/A CUM M51DS1 2 WFC3/IR MULTIAC IR F160W 4 none none none 1 N/A CUM 16508( 5) - 17-May-2021 12:48:27 - [ 8] Visit: 54 (M51DS1_IR) Visit Requirements: On Hold Comments: Additional Comments: HOPR repeat of visit 04 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 M51DS1 WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG 0.000, 0.000; CUM (299.231 SEQ 1-8 NON-INT S) ------------------------------------------------------------------------------------------------------------------------------------ 2 M51DS1 WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG 0.542, 0.182 CUM (299.231 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 M51DS1 WFC3/IR MULTIAC IR F110W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG 0.000, 0.000 CUM (299.231 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 M51DS1 WFC3/IR MULTIAC IR F110W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG 0.542, 0.182 CUM (299.231 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 M51DS1 WFC3/IR MULTIAC IR F110W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG 0.339, 0.485 CUM (299.231 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 M51DS1 WFC3/IR MULTIAC IR F110W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG -0.203, 0.303 CUM (299.231 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 M51DS1 WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG 0.339, 0.485 CUM (299.231 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 M51DS1 WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=STEP100 1 DEF POS TARG -0.203, 0.303 CUM (299.231 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 | ------------------------------------------------------------------------------------------------------------------------------------ M51DS1 1 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM M51DS1 2 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM 16508( 5) - 17-May-2021 12:48:27 - [ 9] 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 | ------------------------------------------------------------------------------------------------------------------------------------ M51DS1 3 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM M51DS1 4 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM M51DS1 5 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM M51DS1 6 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM M51DS1 7 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM M51DS1 8 WFC3/IR MULTIAC IR F160W none none none none 1 N/A CUM 16508( 5) - 17-May-2021 12:48:27 - [ 10] Summary Form for Proposal 16508 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=9, SAMP-SEQ=STEP100 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 3 1, PATTERN 3 2, POS TARG -0.203, 0.303, POS TARG 0.000, 0.000, POS TARG 0.339, 0.485, POS TARG 0.542, 0.182, SEQ 1-8 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F160W, F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M51DS1 ------------------------------------------------------------------------------------------------------------------------------------