0 Assigned ID: 5324 ----- Attempting Submission 1 (Tue Mar 26 04:06:52 GMT 2024) ----- HST Phase I Proposal 5324 successfully submitted. Receipt: # 5324-1 ----- Attempting Submission 2 (Tue Mar 26 22:25:14 GMT 2024) ----- HST Phase I Proposal 5324 successfully submitted. Receipt: # 5324-2 ----- Attempting Submission 3 (Tue Mar 26 22:35:31 GMT 2024) ----- Hi Shelly After some extensive iteration of exposure times, I was able to make Visit 1 to be schedulable over two days, 23 Sep and 25 Sep. Hope this can be scheduled now, its taken quite some time and effort! regards raghvendra 926419979 ----- Attempting Submission 1 (Tue Aug 13 00:07:28 GMT 2024) ----- ----- Attempting Submission 2 (Mon Nov 18 02:21:37 GMT 2024) ----- HST Phase II Proposal 17753 successfully submitted. Receipt: # 17753-2 ----- Attempting Submission 3 (Thu Dec 19 20:01:50 GMT 2024) ----- HST Phase II Proposal 17753 successfully submitted. Receipt: # 17753-3 ----- Attempting Submission 5 (Tue Aug 26 22:25:20 GMT 2025) ----- The dramatic changes in the geometry and dynamics of the mass-ejection during the death throes of most stars that evolve in a Hubble time (i.e., with initial masses ~1-8 Msun), are widely believed to be due to binarity-induced formation of bound disks that power high-speed collimated jets. But observational evidence of this process are lacking. We propose to obtain multi-epoch UV spectra of the nearby (160 pc) late-spectral-type AGB star, pi1 Gru, that belongs to a newly-discovered class of AGB stars showing strong (and often variable) FUV fluxes -- suggestive of variable accretion of matter onto an accretion disk in a binary system. A STIS spectroscopic study of the prototype of this class, Y Gem, showing the presence of flickering and high-velocity infall and outflows, supports this hypothesis. ALMA observations of pi1 Gru reveal strong departures from spherical symmetery in its dusty molecular wind (spiral structure, fast polar bubbles) and the presence of a close companion at ~6 AU, confirmed by optical imaging using SPHERE/ZIMPOL. We will use the UV spectra of pi1 Gru to fit the UV continuum and derive the temperature and size of the accretion hot-spot. Using CLOUDY modelling, we will fit the emission lines to provide constraints on the physical parameters of the accreting flow. The line profiles, if resolved, will reveal the nature of the companion star. Our study will probe the early formation phase of bound disks in binary AGB stars, and provide valuable insights into the binary-induced accretion processes that make such disks, which have long been theorized to drive collimated outflows that produce aspherical morphologies in post-AGB objects. We will obtain multi-epoch UV spectra of pi1 Gru with COS using the G140L (center=1280 A) and G230L (center=2950 & 3360 A) gratings in TIME-TAG mode. The average GALEX FUV (NUV) flux of pi1 Gru is 277(2680) uy. For this source, using COS ETC, we find: FUV: Using the G140L grating, with Cen.Wave. setting lambda=1280 A(B[916-1195], A[1282-2148]) (spectral resolution R ~ 2000 - 5000), we will get a signal-to-noise ratio, S/N, of ~10 for the continuum with an exposure time of 12 min. NUV: Using the G230L grating with two Cen.Wave settings: (i) setting lambda=3360 A (A[2060-2457], B[3162 -3560] and (ii) setting lambda=2950 A (A[1651-2049], A[2751 3150]) (R ~1550 -2900), we get an S/N of ~10 for the continuum with an exposure time of ~1.1 min. As seen from the study of Y Gem (Setal18), the S/N for the lines will be much higher than for the continuum. The above selection of gratings and setting has been made in order to provide nearly fullwavelength coverage at lambda > 916 A in the FUV and NUV (for lambda < 3200 A) bands (since the G230L NUVB spectrum is expected to have negligible second-order contamination shortward of 3200 A.) There will be a ~300 A gap (between 2460 A and 2750 A) in the NUV spectra that we obtain, but it does not impact our ability to reach the science goals of our study. Stripe C of the COS/ MAMA detector may provide potentially useful data over wavelength bands 1900-2100 A for Cen.Wave.=2950 A and 2164 - 2361 A for Cen.Wave.=3360, with about 5% contamination from the first order spectra (ISR COS 2010-01), but these are not critical for our proposed study. Sahai has significant experience in the study of UV emission from astrophysical objects, and has led the publication of a number of well-cited papers related to this topic. In addition, Sahai has published a large number of papers on evolved stars using HST data, including the discovery of the mass-outflow from pi1 Gru and its amazing structure, and predicted the presence of a close companion, The co-Is, all experts in the study of mass-loss from evolved stars, bring valuable complementary experience to the project. Sahai brings over 3 decades of observational experience in studying evolved stars including planetary nebulae, using all major space-based and ground-based observatories (e.g., HST, Chandra, XMM-Newton, Spitzer, ISO, GALEX, SOFIA, Keck, VLA, ALMA) to the proposed study. He has extensive experience with modeling of multiwavelength data to investigate the complex processes of mass ejection in these stars. A highlight of his recent work is the discovery of a new sub-class of AGB stars that show highly variable UV and X-ray emission, likely associated with accretion activity around main-sequence companions -- such stars are the focus of the proposal. Decin's research expertise focusses on (i) the late stages of stellar evolution, (ii) exoplanets and (iii) spectrophotometric calibration of infrared instruments. In her research, she combines observations from world-class observatories, highly sophisticated radiation hydro-chemical numerical simulations, gas-phase and solid-state quantum- and laboratory chemistry, novel mathematical and artificial intelligence concepts. One of her recent papers, of strong relevance for the project here proposed was published in Science: Decin et al. 2020, Science 369, 1497. Montarges is an expert in visible in NIR and visible high angular observations both with interferometry and adaptive optics. He is an experienced user of radio-interferometric facilities such as ALMA and NOEMA, and of 3D dust radiative dust transfer code, and currently works on cool evolved stars and their mass loss. de Koter is an expert on the observational and theoretical studies of massive stars and late evolutionary phases of low-mass stars; his theoretical studies address the properties and dynamics of the photospheres and outflows of these stars in different chemical environments. Sahai will lead the scientific effort, being responsible for the overall management of the study, major scientific analyses and final publication of the results. Stellar Physics and Stellar Types Stellar Physics and Stellar Types 6 false true false false false false SUPPORTED STAR ACCRETION DISK AGB STAR CIRCUMSTELLAR MATTER S STAR NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 COS/FUV Spectroscopic No No G140L 1280 COS/NUV Spectroscopic No No G230L 2950 COS/NUV Spectroscopic No No G230L 3360 COS/FUV Spectroscopic No No G140L 1280 COS/NUV Spectroscopic No No G230L 2950 COS/NUV Spectroscopic No No G230L 3360 1756246882469 Timing link suitability includes constraints ([02 After 01 by 300.0 to 370.0 days]) The scheduling data was generated by CASM 33.1. 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