removed Flexible Data Center as this might violate anonymity rules 427446496 Assigned ID: 1577 ----- Attempting Submission 1 (Wed Apr 07 22:00:43 GMT 2021) ----- HST Phase I Proposal 1577 successfully submitted. Receipt: # 1577-1 ----- Attempting Submission 2 (Thu Apr 08 22:20:29 GMT 2021) ----- HST Phase I Proposal 1577 successfully submitted. Receipt: # 1577-2 ----- Attempting Submission 3 (Fri Apr 09 19:30:49 GMT 2021) ----- We propose a major transformation of the evolutionary synthesis code Starburst99 to meet the needs of the community in the coming decade. A new generation of stellar evolution models optimized for (but not limited to) massive stars has been developed. These models account for the latest progress in nuclear physics, convective processes, differential rotation, and mass loss. They cover the full abundance range from super-solar to metal-free. At the same time, we made enormous strides in exploring the stellar surfaces. The HST ULLYSES program provides the most complete and highest quality ultraviolet spectral library of hot, massive stars. In conjunction with ancillary optical-near-infrared spectra obtained at ESO/VLT and state-of-the-art non-LTE, blanketed, spherical atmospheres, a new generation of stellar-population models can be developed with the synthesis code Starburst99. These models will allow us to understand the processes in star-forming galaxies in the local universe studied, e.g., by the HST Treasury program CLASSY, as well as in galaxies close to the epoch of reionization discovered by JWST. Specific questions to be addressed include (i) quantifying the effects of dust attenuation on the spectral energy distribution, (ii) probing galaxy-scale outflows by providing stellar spectral templates, (iii) providing models for the hardness of the ionizing radiation fields, (iv) exploring the shape of the uppermost stellar initial mass function, and (v) detecting shortcomings in stellar models. We will also convert the current Starburst99 Unix Solaris code into a Linux compatible distribution and migrate the software and the interface to a new, user-friendly platform. The PI Claus Leitherer led the development and release of the original version of Starburst99 in 1999. Since then he participated in numerous collaborations that produced regular upgrades to Starburst99. These collaborations utilized Starburst99 to model UV/optical/near-IR data of star-forming galaxies with an emphasis on the properties of stellar populations. Dr Leitherer has the overall oversight and will lead the technical aspects of the project. Co-I John Chisholm is an expert on the UV properties of star-forming galaxies in the local universe and at high redshift. He is a co-PI of the CLASSY project, and a member of the MEGASAURA team. Co-I Lucimara Martins' expertise is on theoretical and empirical stellar spectral libraries and their implementation in population synthesis codes. She has prior hands-on experience with the Starburst99 code. Co-I Georges Meynet is the lead of the Geneva stellar evolution group. He is a recognized expert on the evolution of massive stars and will serve as our liaison with the Geneva group for the implementation of the tracks. Co-I Andreas Sander is co-developer of the PoWR stellar atmosphere code and has strong expertise in the interpretation of the spectra of hot stars. Co-I Aida Wofford has multi-year experience with analyzing HST UV spectra of star-forming galaxies. She is an experienced Starburst99 user, with an emphasis on modeling metal-poor galaxies Galaxies Stellar Populations and the Interstellar Medium 0 Legacy false false true true false SUPPORTED