0 Assigned ID: 5545 ----- Attempting Submission 1 (Tue Mar 26 18:28:05 GMT 2024) ----- HST Phase I Proposal 5545 successfully submitted. Receipt: # 5545-1 ----- Attempting Submission 2 (Tue Mar 26 22:27:15 GMT 2024) ----- 0 ----- Attempting Submission 1 (Fri Aug 16 20:25:07 GMT 2024) ----- HST Phase II Proposal 17751 successfully submitted. Receipt: # 17751-1 ----- Attempting Submission 2 (Fri Oct 11 04:13:10 GMT 2024) ----- HST Phase II Proposal 17751 successfully submitted. Receipt: # 17751-2 ----- Attempting Submission 3 (Tue Oct 15 22:23:22 GMT 2024) ----- 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. 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 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. PI: Kristina Monsch Kristina Monsch is a Postdoctoral Fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). She has expertise in theoretical analyses of disk and stellar evolution, having authored multiple papers in these topics. She is a co-I/co-PI on a range of ongoing observational studies of protoplanetary disk structures/substructures, including that of Dracula's Chivito, which is the object of interest of this proposal. Kristina will perform the reduction and analysis of the HST data and will lead the publication and presentation of these results. Co-PI: Joshua B. Lovell Joshua Bennett Lovell is a Submillimeter Array (SMA) Postdoctoral Fellow at the Harvard-Smithsonian Center for Astrophysics. He has expertise in observational analyses of disks, having authored multiple papers analysing debris disks with HST and ALMA, including interpreting their dynamical histories and asymmetries. Josh is a co-PI/co-I on a range of ongoing observational studies of debris and protoplanetary disk structures/substructures (including that or Dracula's Chivito, the object of interest in this proposal), and including in additional theoretical disk asymmetry modelling. Co-I: Karl Stapelfeldt Karl Stapelfeldt is NASA's Exoplanet Program Chief Scientist at JPL. He has led HST imaging of edge-on protoplanetary disks since their initial discovery in HST Cycle 4, including scattered light modeling of individual objects, variability studies, and surveys to identify new objects in this class, He has been PI of seven HST GO programs in pursuit of these objectives and principal author on more than a dozen papers on edge-on disks. He is curator of the community disk database https://circumstellardisks.org. Co-I: John H. Debes John Debes is an expert in STIS coronagraphy and has worked on COS, STIS, and WFC3 data in the past. He is also familiar with radiative transfer models of protoplanetary disks. Co-I: David Wilner David Wilner has more than two decades of experience investigating the properties of protoplanetary disks at millimeter wavelengths, including studies of radial and vertical structure, grain growth, chemistry, and kinematics using continuum and spectral line observations from the VLA, SMA and ALMA. Co-I: Jeremy J. Drake Jeremy J. Drake is an expert on stellar outer atmospheres, stellar magnetic activity, and on UV, EUV, and X-ray emission of stars. He has more than two decades of experience working with Chandra, XMM-Newton and HST data. Co-I: Garrett K. Keating Garrett K. Keating is an expert in analysis of interferometric continuum and spectral line data, and will support multi-wavelength analysis of the data. Co-I: Ammar Bayyari Ammar Bayyari is a PhD student in physics and astronomy at the University of Hawaii Manoa. He has experience in observing near-IR using SpeX medium-resolution 0.8-5.5 micron spectrograph and imager for NASA's Infrared Telescope Facility (IRTF), and experience in full SED radiative transfer modeling of protoplanetary disks. Co-I: Michael L. Sitko Michael Sitko is an expert in observing near-IR using SpeX medium-resolution 0.8-5.5 micron spectrograph and imager for NASA's Infrared Telescope Facility (IRTF), and experience in full SED radiative transfer modeling of protoplanetary disks. Co-I: Cecilia Garraffo Cecilia Garraffo is an Astrophysicist at the Chandra X-ray Center. She is an expert on stellar rotation, the resulting energetic radiation, and its effects on exoplanet environments. Stellar Physics and Stellar Types Exoplanets and Exoplanet Formation 6 false false false false false false false false SUPPORTED STAR HERBIG AE/BE PRE-MAIN SEQUENCE STAR PROTOPLANETARY DISK 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. J2000 J2000 Pan-STARRS g: 14.40, r: 14.09, i: 13.94, z: 13.85, y: 13.69 WFC3/UVIS Imaging No No F438W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F105W WFC3/IR Imaging No No F125W WFC3/IR Imaging No No F160W POS-TARG DITHER 5.26 LINE 5.26 false false 90 4 0 WFC3-IR-DITHER-BOX-MIN 1 false 1729021980633 /private/var/folders/y_/tlgj9dy14lnfchth7yq3v6f80000gn/T/OPVisit13050237976882135523.xml The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. 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