17751( 4) - 16-Oct-2024 20:12:16 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17751 Version: 4 Check-in Time: 16-Oct-2024 20:12:16 STScI Edit Number: 0 Title Imaging a monster: HST observations of the asymmetric edge-on disk IRAS 23077+6707 (Dracula's Chivito) ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Kristina Monsch Center for Astrophysics | Harvard & Y Smithsonian CoI: Dr. Josh Bennett Lovell Smithsonian Institution Astrophysical Y Observatory CoI: Dr. Karl Stapelfeldt Jet Propulsion Laboratory N CoI: Dr. David Wilner Smithsonian Institution Astrophysical N Observatory CoI: Dr. Jeremy J. Drake Lockheed Martin Space N CoI: Dr. Cecilia Garraffo Smithsonian Institution Astrophysical N Observatory CoI: Mr. Ammar Bayyari University of Hawaii N CoI: Dr. Garrett K. Keating Center for Astrophysics | Harvard & N Smithsonian CoI: Dr. John Henry Debes Space Telescope Science Institute - ESA - N JWST CoI: Dr. Michael L. Sitko Space Science Institute N ------------------------------------------------------------------------------------ Abstract We propose the first sub-arcsecond imaging campaign of the giant, asymmetric edge-on disk IRAS 23077+6707 (Dracula's Chivito/DraChi) to study its dust grain structure and evolution from 0.4-1.7 microns. DraChi is enormous: spanning approx. 14 arcsec on the sky, it is far in excess of any average protoplanetary disk extents, making it the largest protoplanetary disk thus far discovered. Moreover, this disk is highly asymmetric, yet has only been imaged at low resolution from the ground with Pan-STARRS. These images show not only two faint filaments in the disk's northern part that extend well beyond 20 arcsec, but also various brightness asymmetries. We propose the imaging of this enigmatic disk in only three HST orbits using the WFC3/UVIS broadband filters F438W, F606W and F814W and the WFC3/IR broadband filters F105W, F125W and F160W to map at unprecedented angular scales the wavelength dependence of the disk's midplane thickness, determine the dust grain properties and the degree of their vertical settling and ultimately probe the extent to which ongoing planet formation is driving DraChi's asymmetric substructures. ------------------------------------------------------------------------------------ Observations Description ------------------------ We require HST observations using in total three WFC3 UVIS and three IR filters. For WFC3/UVIS we selected filters F438W, F606W and F814W to cover the full breadth of the optical spectrum previously only studied by Pan-STARRS. These filters will image the scattered light emission arising from the smallest, sub-micron-sized dust grains entrained in the uppermost layers of the disk's atmosphere. As a bonus, the combination of filters F606W and F814W is 17751( 4) - 16-Oct-2024 20:12:16 - [ 2] ideal for distinguishing faint jet emission (if present) from the disk's reflected light, which is present in both bands, while jet-emission should be nearly absent in F814W. Similar filter combinations have proven highly successful in previous cycles targeting other edge-on disks. In order to leverage HST's full IR-capabilities and obtain the first resolved IR images of DraChi, the images from the optical filters will be combined with three rather short IR exposures obtained by WFC3/IR using the F105W, F125W and F160W filters. This filter combination will allow us to probe the scattered light emission arising from larger dust grains that are located in deeper and less elevated layers than the optically scattering dust and thus allow us to measure DraChi's vertical disk extent across a decade of wavelengths. Exposure times for each filter were chosen such that the faint, northern filaments will be detected with an SNR of at least 60, while ensuring the observations will not saturate for the bright, central regions of the disk, for which we estimate obtaining an SNR of at least 1000. While being a non-standard approach, we will not perform any dither maneuvers for the UVIS filters, as the combination of dithered images is usually done using interpolation, which however blurs the final image. Typical scale heights of previously studied edge-on disks are close to 7 au (e.g. Williams & Cieza 2011, Stapelfeldt et al. 2014), which is close to 0.05 arcsec at the distance to nearby star-forming regions. The undithered HST PSF is aprox. 0.1 arcsec at F606W, but blurs to approx. 0.15 arcsec when the dithered images are combined. Consequently, dithering would make it significantly harder to retrieve the disk's scale height from fitting of the combined images, which is one of our main science goals. Instead we will opt for CR-splitting the UVIS-exposures with no dither, and subsequently remove the hot pixels via median filtering. For WFC3/IR, however, the pixel scale is about 3x larger than for WFC3/UVIS, and thus blurring from dithered images matters a lot less at IR-wavelengths and consequently a 4-point dither maneuver will be performed for each WFC3/IR exposure. Additionally, for WFC3/IR the 512x512 subarray will be used, which reduces the data volume and the overheads for buffer readout. ------------------------------------------------------------------------------------ 17751( 4) - 16-Oct-2024 20:12:16 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 IRAS23077+67 STAR, HERBIG AE/BE, RA=23H09M43.6450S, J2000 V = 14.23 +/- 0.1 Pan-STARRS g: 14.40, 07 PRE-MAIN SEQUENCE STAR, DEC=+67D23'38.94" r: 14.09, i: 13.94, z: 13.85, y: 13.69 PROTOPLANETARY DISK Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Fluxes were calculated within a 14arcsec aperture centred on the source position. 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 ------------------------------------------------------------------------------------------------------------------------------------ 17751( 4) - 16-Oct-2024 20:12:16 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 5.26 Line_Spacing 5.26 Coordinate_Frame POS-TARG Pattern_Orient 0 Angle_Between_Sides 90 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17751( 4) - 16-Oct-2024 20:12:16 - [ 5] Visit: 01 Visit Requirements: SCHED 50% 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 IRAS23077+6 WFC3/UVI ACCUM UVIS1 F438W CR-SPLIT=4, FLASH=15 1 2000 S 707 S (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 IRAS23077+6 WFC3/UVI ACCUM UVIS1 F438W CR-SPLIT=NO, FLASH=20 1 100 S (100 707 S S) ------------------------------------------------------------------------------------------------------------------------------------ 3 IRAS23077+6 WFC3/UVI ACCUM UVIS1 F606W CR-SPLIT=2, FLASH=5 1 600 S (600 707 S S) ------------------------------------------------------------------------------------------------------------------------------------ 4 IRAS23077+6 WFC3/UVI ACCUM UVIS1 F814W CR-SPLIT=2, FLASH=10 1 950 S (950 707 S S) ------------------------------------------------------------------------------------------------------------------------------------ 5 IRAS23077+6 WFC3/UVI ACCUM UVIS1 F814W CR-SPLIT=NO, FLASH=15 1 70 S (70 707 S S) ------------------------------------------------------------------------------------------------------------------------------------ 6 IRAS23077+6 WFC3/IR MULTIAC IRSUB512 F125W SAMP-SEQ=SPARS25, NSAMP=8 1 DEF SEQ 6-8 NON-INT; PATTERN 707 CUM (645.207 1 6 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 IRAS23077+6 WFC3/IR MULTIAC IRSUB512 F105W SAMP-SEQ=SPARS25, NSAMP=8 1 DEF PATTERN 1 7 707 CUM (645.207 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 IRAS23077+6 WFC3/IR MULTIAC IRSUB512 F160W SAMP-SEQ=SPARS25, NSAMP=8 1 DEF PATTERN 1 8 707 CUM (645.207 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 | ------------------------------------------------------------------------------------------------------------------------------------ IRAS23077+6707 1 WFC3/UVI ACCUM UVIS1 F438W none none none 1 1 N/A S IRAS23077+6707 1 WFC3/UVI ACCUM UVIS1 F438W none none none 2 1 N/A S IRAS23077+6707 1 WFC3/UVI ACCUM UVIS1 F438W none none none 3 1 N/A S IRAS23077+6707 1 WFC3/UVI ACCUM UVIS1 F438W none none none 4 1 N/A S 17751( 4) - 16-Oct-2024 20:12:16 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ IRAS23077+6707 2 WFC3/UVI ACCUM UVIS1 F438W none none none none 1 N/A S IRAS23077+6707 3 WFC3/UVI ACCUM UVIS1 F606W none none none 1 2 N/A S IRAS23077+6707 3 WFC3/UVI ACCUM UVIS1 F606W none none none 2 2 N/A S IRAS23077+6707 4 WFC3/UVI ACCUM UVIS1 F814W none none none 1 2 N/A S IRAS23077+6707 4 WFC3/UVI ACCUM UVIS1 F814W none none none 2 2 N/A S IRAS23077+6707 5 WFC3/UVI ACCUM UVIS1 F814W none none none none 2 N/A S IRAS23077+6707 6 WFC3/IR MULTIAC IRSUB512 F125W 1 none none none 3 N/A CUM IRAS23077+6707 6 WFC3/IR MULTIAC IRSUB512 F125W 2 none none none 3 N/A CUM IRAS23077+6707 6 WFC3/IR MULTIAC IRSUB512 F125W 3 none none none 3 N/A CUM IRAS23077+6707 6 WFC3/IR MULTIAC IRSUB512 F125W 4 none none none 3 N/A CUM IRAS23077+6707 7 WFC3/IR MULTIAC IRSUB512 F105W 1 none none none 3 N/A CUM IRAS23077+6707 7 WFC3/IR MULTIAC IRSUB512 F105W 2 none none none 3 N/A CUM IRAS23077+6707 7 WFC3/IR MULTIAC IRSUB512 F105W 3 none none none 3 N/A CUM IRAS23077+6707 7 WFC3/IR MULTIAC IRSUB512 F105W 4 none none none 3 N/A CUM IRAS23077+6707 8 WFC3/IR MULTIAC IRSUB512 F160W 1 none none none 3 N/A CUM IRAS23077+6707 8 WFC3/IR MULTIAC IRSUB512 F160W 2 none none none 3 N/A CUM IRAS23077+6707 8 WFC3/IR MULTIAC IRSUB512 F160W 3 none none none 3 N/A CUM IRAS23077+6707 8 WFC3/IR MULTIAC IRSUB512 F160W 4 none none none 3 N/A CUM 17751( 4) - 16-Oct-2024 20:12:16 - [ 7] Summary Form for Proposal 17751 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IRSUB512, UVIS1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2, CR-SPLIT=4, CR-SPLIT=NO, FLASH=10, FLASH=15, FLASH=20, FLASH=5, NSAMP=8, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 6, PATTERN 1 7, PATTERN 1 8, SCHED 50%, SEQ 6-8 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F105W, F125W, F160W, F438W, F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names IRAS23077+6707 ------------------------------------------------------------------------------------------------------------------------------------