15361( 4) - 12-Jul-2017 10:53:58 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15361 Version: 4 Check-in Time: 12-Jul-2017 10:53:58 STScI Edit Number: 0 Title The Mysterious High-Velocity Ejecta Jets in Cassiopeia A ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Robert A. Fesen Dartmouth College Y CoI: Dr. Dan Milisavljevic Smithsonian Institution Astrophysical N Observatory ------------------------------------------------------------------------------------ Abstract The young Galactic remnant Cas A provides perhaps our clearest look at the explosion of a high mass, core-collapse supernova. Two opposing streams or "jets" of high-velocity debris extending outward along its northeastern and southwestern limbs have expansion velocities more than twice that of the remnant's bright main shell. Interpretation of these NE-SW jets has been controversial. However, SN debris located at the farthest tip of the NE jet has been found to be S, Ar, Ca-rich but O-poor suggesting an origin deep inside the progenitor possibly due to an overturning of layers as predicted in some aspherical explosion models. Recent WFC3/IR images taken of the NE jet revealed a far richer debris field than previously realized, with ejecta knots found out to the very edge of the camera's FOV. This leaves uncertain the jet's true maximum velocity and total kinetic energy. The lack of a complete census of the jet's structure and kinematics critically limits understanding on the nature of these puzzling kinematic and chemically distinct features. We propose to obtain WFC3/IR images of the remnant's NE jet out beyond existing HST images to complete a survey of its S-rich ejecta and explore the presence of even higher-velocity, Fe-rich ejecta predicted by supernova models. Detection of very high-velocity Fe-rich material in the jet would represent a breakthrough in our understanding of Cas A and core-collapse supernovae in general. ------------------------------------------------------------------------------------ Observations Description ------------------------ The aim of this project is to obtain WFC3/IR images of two regions near the young supernova remnant, Cassiopeia A, in two filters: the F098M filter to detect [S III] 9069, 9531 and [S II] 10250-10, 400 emission lines, while the F160N filter images will detect [Fe II] 1.64 emission from Fe-rich ejecta. Two adjacent and slightly overlapping fields will be imaged in both filters. We will employ a four point dither pattern for these images. The features we are trying to detect are small (0.5" or less) emission blobs using the F098M filter, and eitehr small ejecta knots/blobs of patches of diffuse emission in the F164N images. These images will serve as the first set of images to be combined with a nearly identical set of images taken in Cycle 25. ------------------------------------------------------------------------------------ 15361( 4) - 12-Jul-2017 10:53:58 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CAS-A-NE-JET ISM, EJECTA, EMISSION RA=23H24M2.0000S +/- 0.4", J2000 V = 24 +/- 2 -1 LINE NEBULA DEC=+58D51'0.00" +/- 0.4" Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 2 CAS-A-NE-JET ISM, EJECTA, EMISSION RA=23H24M17.0000S, J2000 V = 25 +/- 2 -2 LINE NEBULA DEC=+58D51'50.00" Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 15361( 4) - 12-Jul-2017 10:53:58 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 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 ------------------------------------------------------------------------------------------------------------------------------------ 15361( 4) - 12-Jul-2017 10:53:58 - [ 4] Visit: 01 Visit Requirements: ORIENT 111.7D TO 112.1 D; AFTER 01-OCT-2018; GROUP 01, 02 WITHIN 60D 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 CAS-A-NE-JE WFC3/IR MULTIAC IR-FIX F098M NSAMP=15, SAMP-SEQ=SPARS50 1 DEF PATTERN 1 1 T-1 CUM (2811.754 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CAS-A-NE-JE WFC3/IR MULTIAC IR-FIX F164N NSAMP=13, SAMP-SEQ=STEP100 1 DEF PATTERN 1 2 T-1 CUM (2796.93 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 | ------------------------------------------------------------------------------------------------------------------------------------ CAS-A-NE-JET-1 1 WFC3/IR MULTIAC IR-FIX F098M 1 none none none 1 N/A CUM CAS-A-NE-JET-1 1 WFC3/IR MULTIAC IR-FIX F098M 2 none none none 1 N/A CUM CAS-A-NE-JET-1 1 WFC3/IR MULTIAC IR-FIX F098M 3 none none none 1 N/A CUM CAS-A-NE-JET-1 1 WFC3/IR MULTIAC IR-FIX F098M 4 none none none 1 N/A CUM CAS-A-NE-JET-1 2 WFC3/IR MULTIAC IR-FIX F164N 1 none none none 2 N/A CUM CAS-A-NE-JET-1 2 WFC3/IR MULTIAC IR-FIX F164N 2 none none none 2 N/A CUM CAS-A-NE-JET-1 2 WFC3/IR MULTIAC IR-FIX F164N 3 none none none 2 N/A CUM CAS-A-NE-JET-1 2 WFC3/IR MULTIAC IR-FIX F164N 4 none none none 2 N/A CUM 15361( 4) - 12-Jul-2017 10:53:58 - [ 5] Visit: 02 Visit Requirements: ORIENT 111.7D TO 112.1 D; AFTER 01-OCT-2018 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 CAS-A-NE-JE WFC3/IR MULTIAC IR-FIX F098M NSAMP=15, SAMP-SEQ=SPARS50 1 DEF PATTERN 1 1 T-2 CUM (2811.754 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CAS-A-NE-JE WFC3/IR MULTIAC IR-FIX F164N NSAMP=13, SAMP-SEQ=STEP100 1 DEF PATTERN 1 2 T-2 CUM (2796.93 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 | ------------------------------------------------------------------------------------------------------------------------------------ CAS-A-NE-JET-2 1 WFC3/IR MULTIAC IR-FIX F098M 1 none none none 1 N/A CUM CAS-A-NE-JET-2 1 WFC3/IR MULTIAC IR-FIX F098M 2 none none none 1 N/A CUM CAS-A-NE-JET-2 1 WFC3/IR MULTIAC IR-FIX F098M 3 none none none 1 N/A CUM CAS-A-NE-JET-2 1 WFC3/IR MULTIAC IR-FIX F098M 4 none none none 1 N/A CUM CAS-A-NE-JET-2 2 WFC3/IR MULTIAC IR-FIX F164N 1 none none none 2 N/A CUM CAS-A-NE-JET-2 2 WFC3/IR MULTIAC IR-FIX F164N 2 none none none 2 N/A CUM CAS-A-NE-JET-2 2 WFC3/IR MULTIAC IR-FIX F164N 3 none none none 2 N/A CUM CAS-A-NE-JET-2 2 WFC3/IR MULTIAC IR-FIX F164N 4 none none none 2 N/A CUM 15361( 4) - 12-Jul-2017 10:53:58 - [ 6] Summary Form for Proposal 15361 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, NSAMP=15, SAMP-SEQ=SPARS50, SAMP-SEQ=STEP100 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01-OCT-2018, GROUP 01, 02 WITHIN 60D, ORIENT 111.7D TO 112.1 D, PATTERN 1 1, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F098M, F164N ------------------------------------------------------------------------------------------------------------------------------------ Target Names CAS-A-NE-JET-1, CAS-A-NE-JET-2 ------------------------------------------------------------------------------------------------------------------------------------