17096( 3) - 03-Oct-2022 10:42:34 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17096 Version: 3 Check-in Time: 03-Oct-2022 10:42:34 STScI Edit Number: 0 Title Linking the UV Bump with PAHs in Low Metallicity Starburst II Zw 40 ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Thomas Lai California Institute of Technology Y CoI: Dr. Lee Armus California Institute of Technology N CoI: Prof. Aaron S. Evans The University of Virginia N CoI: Dr. Sean Linden University of Massachusetts - Amherst N CoI: Dr. Jeffrey Austin Sterling Rich Carnegie Institution of Washington N Jr. ------------------------------------------------------------------------------------ Abstract We proposed to explore the connection between the 2175 angstrom UV bump and the Polycyclic Aromatic Hydrocarbons (PAHs) together with the cluster properties in a prototypical blue compact dwarf II Zw 40 using the FUV-NUV-optical filters F140LP, F225W, and F438W. The debate on what the carriers of the UV bump are is still unsettled, but PAH is one of the most plausible candidates. II Zw 40 has one of the highest star formation rate densities in the local Universe and has been found to exhibit strong 3.3 micron emission powered by the smallest PAHs. Our observation will take the advantage of the scheduled JWST GO1 program and use it as a supplement to showcase the combined power of the HST UV imaging and JWST IFUs to achieve our goal. Blue compact dwarf allows us to study starburst phenomena in the early Universe since they serve as powerful low-z, spatially resolvable analogs to high-z galaxies. Using HST multi-band imaging, we will constrain the strength of the UV bump and compare it with the spatially resolved dust properties in the IR revealed by JWST's IFUs. With our observation, we will also make possible a complete inventory of star clusters in II Zw 40 to further study cluster formation and evolution in this galaxy. There are existing archival HST UV data but they are not deep enough to meet our scientific objective. Our proposed program will obtain a much deeper UV mapping of II Zw 40 so that the amplitude of the UV bump can be better constrained. In total, we request 5 orbits of the HST observing time. ------------------------------------------------------------------------------------ Observations Description ------------------------ HST images will be obtained using the ACS/SBC F140LP and WFC3/UVIS F225W and F438W filters. The exposure time for each filter is estimated using the HST ETC. For each filter, we use 4 point dithering with a post flash of 20 e-. The SED used in the ETC is 5 Myr old simple stellar population with Z_sun=0.4 from (Bruzual & Charlot, 2003). A set of the available HST archival data, including STIS F25QTZ and F25CN270 together with ACS F555W, is used to set the spectral normalize point for the exposure time estimation. The proposed observations will allow us to achieve a SNR>7 in the faintest clusters visible in the STIS image (see Sect. Justify Duplication for detail). We request 2 orbits in each of the F140LP and F225W filter to obtain deep UV images and 1 orbit for the optical filter F438W. Note that if these faint clusters are younger, their 17096( 3) - 03-Oct-2022 10:42:34 - [ 2] spectral energy distributions peak even higher in the bluer filters, and would be 1-2 magnitudes brighter than described above. In total, we request 5 orbits targeting II Zw 40 in this program. ------------------------------------------------------------------------------------ 17096( 3) - 03-Oct-2022 10:42:34 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 UGCA-116 GALAXY, STARBURST RA=05H55M42.6450S, J2000 V = 11.46 DEC=+03D23'32.23" Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17096( 3) - 03-Oct-2022 10:42:34 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-SBC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.179 Line_Spacing 0.116 Coordinate_Frame POS-TARG Pattern_Orient 20.02 Angle_Between_Sides 63.65 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.173 Line_Spacing 0.112 Coordinate_Frame POS-TARG Pattern_Orient 23.884 Angle_Between_Sides 81.785 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17096( 3) - 03-Oct-2022 10:42:34 - [ 5] Visit: 01 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 UGCA-116 ACS/SBC ACCUM SBC F140LP 1 1300 S PATTERN 1 1 (5200 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 | ------------------------------------------------------------------------------------------------------------------------------------ UGCA-116 1 ACS/SBC ACCUM SBC F140LP 1 none none none 1 N/A UGCA-116 1 ACS/SBC ACCUM SBC F140LP 2 none none none 1 N/A UGCA-116 1 ACS/SBC ACCUM SBC F140LP 3 none none none 2 N/A UGCA-116 1 ACS/SBC ACCUM SBC F140LP 4 none none none 2 N/A 17096( 3) - 03-Oct-2022 10:42:34 - [ 6] Visit: 02 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 UGCA-116 WFC3/UVI ACCUM UVIS2 F225W CR-SPLIT=NO, FLASH=15 1 1296 S PATTERN 2 1 S (5184 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 | ------------------------------------------------------------------------------------------------------------------------------------ UGCA-116 1 WFC3/UVI ACCUM UVIS2 F225W 1 none none none 1 N/A S UGCA-116 1 WFC3/UVI ACCUM UVIS2 F225W 2 none none none 1 N/A S UGCA-116 1 WFC3/UVI ACCUM UVIS2 F225W 3 none none none 2 N/A S UGCA-116 1 WFC3/UVI ACCUM UVIS2 F225W 4 none none none 2 N/A S 17096( 3) - 03-Oct-2022 10:42:34 - [ 7] Visit: 03 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 UGCA-116 WFC3/UVI ACCUM UVIS2 F438W FLASH=15, CR-SPLIT=NO 1 500 S PATTERN 2 1 S (2000 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 | ------------------------------------------------------------------------------------------------------------------------------------ UGCA-116 1 WFC3/UVI ACCUM UVIS2 F438W 1 none none none 1 N/A S UGCA-116 1 WFC3/UVI ACCUM UVIS2 F438W 2 none none none 1 N/A S UGCA-116 1 WFC3/UVI ACCUM UVIS2 F438W 3 none none none 1 N/A S UGCA-116 1 WFC3/UVI ACCUM UVIS2 F438W 4 none none none 1 N/A S 17096( 3) - 03-Oct-2022 10:42:34 - [ 8] Summary Form for Proposal 17096 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures SBC, UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/SBC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO, FLASH=15 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140LP, F225W, F438W ------------------------------------------------------------------------------------------------------------------------------------ Target Names UGCA-116 ------------------------------------------------------------------------------------------------------------------------------------