HSTbanner

AR 14568 (Archival Research)

Thu Jul 25 12:35:11 GMT 2024

Principal Investigator: D. Hillier
PI Institution: University of Pittsburgh
Investigators (xml)

Title: Spectroscopic Analysis: A Key Tool for Understanding the Universe
Cycle: 24

Abstract
Spectroscopic analysis is a key tool for understanding the nature of stars and supernovae. To facilitate advances in spectroscopic analysis we will significantly enhance and extend the capabilities of our time-dependent radiative transfer code, CMFGEN. As part of these improvements we will expand one of the associated codes to handle complex photospheric velocity fields, and we will investigate and test new methods to better treat multi-component winds. CMFGEN has been extensively used to study luminous blue variables, O stars, Wolf-Rayet stars, [W-R] central stars of planetary nebulae, and most types of supernovae. All these objects have been extensively observed by HST. CMFGEN, with documentation and sample models, is available at www.pitt.edu/~hillier. O stars, and their descendants, play a crucial role in galaxy evolution. They are a dominant source of ionizing radiation, and through their winds and supernovae explosions they deposit momentum and energy into the interstellar medium. They are also responsible for many of the key elements (e.g., O, Mg, Si) necessary for life. Despite advances we still lack a firm understanding of massive star evolution: What is the role of rotation in massive star evolution and how does it change with metallicity? How does rotation affect surface abundances? What is the origin of turbulence in massive stars? How does the supernova subtype correlate with a star's initial mass? What is the relative importance of single stars compared with binary systems for producing Wolf-Rayet stars and supernovae? We can address many of these questions (or at least provide important constraints) by performing accurate spectroscopic analyses.