0 Assigned ID: 977 ----- Attempting Submission 1 (Fri Apr 05 23:43:47 GMT 2019) ----- HST Phase I Proposal 977 (boom-cyc27.apt) successfully submitted. Receipt: # 977-1 ----- Attempting Submission 2 (Fri Apr 05 23:47:47 GMT 2019) ----- Hi Tala, i've made the changes as recommended. thanks for all your help! there is is 178 sec of unused visibility in first orbit, i tried to make the orbit planner use it by AUTO-ADJUST, but it didn't help raghvendra 1502472307 ----- Attempting Submission 1 (Tue Jul 23 17:23:00 GMT 2019) ----- ----- Attempting Submission 2 (Wed Apr 08 00:32:07 GMT 2020) ----- The Boomerang Nebula, is the coldest (naturally occurring) object in the Universe. CO(1-0) observations of it show a massive ultra-cold outflow in absorption against the microwave background, implying that the nebula has cooled below the temperature of the cosmic background radiation. Its extreme properties make it the Rosetta Stone for understanding the mass-loss processes that govern late stellar evolution. Our recent ALMA study shows that the Boomerang is the product of a common-envelope event (CEE) in a binary system, while the primary was an RGB/early-AGB star, which ejected the primary's envelope that now forms the ultra-cold outflow. It is likely that the companion merged into the primary's core, leaving a single G-type star with a large dusty disk. This disk may be the launch site of a jet that has sculpted the inner regions of the ultra-cold outflow, producing the bipolar nebula at the center. HST polarised-light imaging shows the presence of two point-symmetric spurs around the central star, that likely result from such a jet. Previous ground-based spectroscopy shows absorption and emission lines that are likely associated with this jet. We propose to obtain long-slit spectroscopy with STIS in order to confirm the presence of the jet and probe its spatio-kinematic structure. These data will provide us with unprecedented details of the product of a CEE event, and the launching of jets from the central source - a fundamental, yet very poorly understood astrophysical process. Our analysis will use the results of a recent theoretical study that shows how one can constrain basic properties of the jet engine by studying the jet properties. We will use STIS with G750M centered at 6581\,\AA~and a mosaic of 10 parallel slits aligned along the axis of the central bipolar nebula (i.e. PA=353\arcdeg), to probe the spatio-kinematic structure of the jet and shocked regions where it impacts the walls of the bipolar cavity. We will use the the $52{''}\times$0\farcs2 slit to obtain spectra in the $\lambda\lambda$6295-6867\,\AA range with $\sim$50\,\kms~spectral and 0.05 arcsec spatial resolution. We will thus cover the H$\alpha$, [NII]\,6548,6583 and [SII]\,6717,6731 lines, the [OI]6300 line will be near the edge, but still visible. The average H$\alpha$, [NII] and [SII] average line intensities are in the range $\sim3.5\times10^{-15}-1.5\times10^{-15}$ erg\,s$^{-1}$\,cm$^{-2}$\,arcsec$^{-2}$. The line-widths (marginally resolved) are about $70-90$\,\kms. Since the line intensities are likely not uniform, we assume a variation of a factor 3, and a minimum S/N ratio of about 10 in the regions of lowest intensity in our weakest lines, i.e., [SII]\,6717,6731, which are important for measuring the densities in the jet; the S/N obtained on the H$\alpha$ absorption line will be larger. A high S/N for the latter is important, as it is the only tracer that we have for the unshocked gas in the jet. Using the STIS Exposure Time Calculator, we estimate that an exposure time of about 1100\,s will be needed. Thus, for our mosaic of 10 slits, we will need 183 minutes of exposure time, i.e., 4 orbits (with 50\,min per orbit to allow increase in Scheduling Flexibility, as per the APT). From the observed PA of the bipolar nebula (353\arcdeg), we compute an $ORIENT=PA+46.3\arcdeg\sim39\arcdeg$ or $PA+226.3\arcdeg\sim219\arcdeg$ (as per the STIS handbook). We therefore request a slit ORIENT range $PA=34\arcdeg-44\arcdeg$, or $214\arcdeg-224\arcdeg$, in order to probe the emission from the highly-collimated jet precisely. This ORIENT range, although restricted, allows a substantial $\gtrsim$1-month long window for scheduling. All investigators on this proposal have decades of experience studying evolved stars, including pre-planetary and planetary nebulae, both via observations and modeling, and are well recognized internationally for their work. All team members have published a large number of well-cited papers dealing with the analysis of HST data on PNe. The PI, 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. Dr. Nyman was, with Sahai, the co-discoverer of the Boomerang Nebula as the Coldest place in the Universe. Both Drs. Vlemmings and Nyman have been main co-authors in recent studies of the Boomerang Nebula, using ALMA. They have also been very active in the study of mass-ejection on the AGB and beyond, using molecular-line observations. Prof. Blackman is one of the world's top experts in theoretical studies of jet and disk formation during the AGB-to-PN transition. 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 6 false false false false false false 0.0 0.0 false SUPPORTED STAR POST-AGB STAR YES J2000 J2000 STIS/CCD Spectroscopic No No G750M 6581 POS-TARG MOSAIC DITHER 3 0.2 pattern should produce a mosaice of 10 parallel slits, with a grid spacing of 0.2 arcsec for each slit location, there should be 3 dithered exposures STIS-ALONG-SLIT false true 0.380325 10 0.0 POS-TARG STIS-PERP-TO-SLIT 90.0 1 true 1586305849723 /tmp/OPVisit13786538037726910362.xml The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. 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