second submission -2007122312 Assigned ID: 703 ----- Attempting Submission 1 (Fri Mar 06 19:35:00 GMT 2020) ----- HST Phase I Proposal 703 successfully submitted. Receipt: # 703-1 ----- Attempting Submission 2 (Fri Mar 06 23:05:26 GMT 2020) ----- The Magellanic Clouds are connected to an extended tail of neutral and ionized gas known as the Magellanic Stream. The Stream's mass, morphology, spatial extent and metallicity cannot be fully explained by current numerical simulations, which assume tidal interactions or ram-pressure stripping as the origin mechanism. Preliminary results from new hydrodynamical simulations suggest that the existence of a warm corona around the LMC significantly affects the formation of the Stream; these simulations may for the first time be able to explain both the Stream's large ionized gas mass and the existence of its Leading Arm. A warm corona is motivated by the LMC's high mass and by the detection of interstellar CIV absorption in the spectra of hot stars in the LMC. To test and validate the warm-corona hypothesis, we propose to analyze 30 archival HST/COS spectra of AGN at LMC impact parameters between 3 and 35 kpc to determine the extent and properties of the LMC corona. Using measurements of SiIV and CIV absorption, we will derive the corona's size, density profile, ionization state, and temperature, which is crucial to constrain our modeling of the Magellanic system. This archival analysis offers the potential to solve the 50-year enigma of the origin of the Magellanic Stream. PI Dr Elena D'Onghia, is an expert in numerical simulations of the Magellanic Stream and will coordinate the whole project and ensure its execution on schedule and the release of the simulation products. She will also supervise graduate student Scott Lucchini who will carry out the simulations as part of his PhD thesis work. Mr Scott Lucchini is a graduate student working with D'Onghia on the modeling of the Stream and has implemented the warm LMC corona part of the simulation Dr Andrew Fox is an expert in the reduction, analysis, and interpretation of HST/COS spectra of diffuse gas in the Universe. He has led five HST GO proposals in closely related science areas (Milky Way CGM), all of which have led to refereed publications and NASA press releases, and has first-authored 11 ApJ papers using UV spectroscopy. Dr Bart Wakker has an extensive background in studies of the interstellar and intergalactic medium, having published over 100 papers on these subjects, using data from ground-based radio and optical telescopes, as well as many of the UV space instruments (IUE, FUSE, FOS, GHRS, STIS, COS), being PI on 11 HST observing and 4 HST archival projects, as well as Co-PI or Admin-PI on 7 others. Dr. Nicolas Lehner is an expert in the reduction, analysis, and interpretation of HST/COS spectra of interstellar, intergalactic, and circumgalactic gas in the Universe at all redshifts. He is the PI of several HST GO and AR programs, including one Large and two Legacy programs that all led to numerous refereed publications and several NASA press releases. Dr. Chris Howk is an expert in analyzing interstellar absorption in complicated stellar spectra including supergiant early-type stars and with PI Wakker was responsible for the first detection of coronal CIV in the LMC. He has led several large programs in the Milky disk, halo, and in the LMC that have used as UV background objects hot stars of all types. Galaxies Galaxies 0 Regular false false true false false SUPPORTED