The unique capabilities of HST for stellar physics Probing Atmospheric Structure, Chromospheres, and Mass Loss of Evolved Stars

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Main Authors: Saberi, Maryam, Harper, Graham, van Loon, Jacco Th., Dupree, Andrea K., Vlemmings, Wouter, Höfner, Susanne, Khouri, Theo, Wedemeyer, Sven, Humphreys, Roberta, Luttermoser, Donald, Javadi, Atefeh, Kervella, Pierre, Wiegert, Joachim
Format: Preprint
Published: 2026
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author Saberi, Maryam
Harper, Graham
van Loon, Jacco Th.
Dupree, Andrea K.
Vlemmings, Wouter
Höfner, Susanne
Khouri, Theo
Wedemeyer, Sven
Humphreys, Roberta
Luttermoser, Donald
Javadi, Atefeh
Kervella, Pierre
Wiegert, Joachim
author_facet Saberi, Maryam
Harper, Graham
van Loon, Jacco Th.
Dupree, Andrea K.
Vlemmings, Wouter
Höfner, Susanne
Khouri, Theo
Wedemeyer, Sven
Humphreys, Roberta
Luttermoser, Donald
Javadi, Atefeh
Kervella, Pierre
Wiegert, Joachim
contents Evolved stars are among the primary sources of chemical enrichment and dust production in galaxies. During the giant phases, stars return a substantial fraction of their mass to the interstellar medium (ISM) through stellar winds, enriching galaxies with newly synthesized elements and dust. However, the atmospheric structure and physical processes that initiate mass loss remain poorly constrained observationally. Understanding the origin, structure, and evolution of stellar chromospheres remains a long-standing problem in stellar astrophysics. While the mechanisms responsible for chromospheric heating and atmospheric dynamics are not fully understood even in the Sun, they become more complex in evolved stars due to pulsation, shocks, convection, extended atmospheres, and possible magnetic activity. Determining the thermal, density, and velocity structure of these extended atmospheres is therefore essential for understanding atmospheric heating, the onset of mass loss, and the late stages of stellar evolution. High-resolution NUV and FUV spectroscopy (R ~ 30,000-100,000) provided by HST/STIS occupies a unique observational parameter space that cannot be replaced by existing facilities. HST/STIS therefore remains essential for understanding the atmospheric physics and mass-loss processes of evolved stars. We highlight the need to preserve and prioritize high-resolution NUV and FUV spectroscopic capabilities with HST. Such programs would provide essential benchmarks for stellar atmosphere modeling, complement ongoing ALMA and optical observations, and help define future UV-optical capabilities for the Habitable Worlds Observatory (HWO).
format Preprint
id arxiv_https___arxiv_org_abs_2605_22956
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The unique capabilities of HST for stellar physics Probing Atmospheric Structure, Chromospheres, and Mass Loss of Evolved Stars
Saberi, Maryam
Harper, Graham
van Loon, Jacco Th.
Dupree, Andrea K.
Vlemmings, Wouter
Höfner, Susanne
Khouri, Theo
Wedemeyer, Sven
Humphreys, Roberta
Luttermoser, Donald
Javadi, Atefeh
Kervella, Pierre
Wiegert, Joachim
Solar and Stellar Astrophysics
Astrophysics of Galaxies
Evolved stars are among the primary sources of chemical enrichment and dust production in galaxies. During the giant phases, stars return a substantial fraction of their mass to the interstellar medium (ISM) through stellar winds, enriching galaxies with newly synthesized elements and dust. However, the atmospheric structure and physical processes that initiate mass loss remain poorly constrained observationally. Understanding the origin, structure, and evolution of stellar chromospheres remains a long-standing problem in stellar astrophysics. While the mechanisms responsible for chromospheric heating and atmospheric dynamics are not fully understood even in the Sun, they become more complex in evolved stars due to pulsation, shocks, convection, extended atmospheres, and possible magnetic activity. Determining the thermal, density, and velocity structure of these extended atmospheres is therefore essential for understanding atmospheric heating, the onset of mass loss, and the late stages of stellar evolution. High-resolution NUV and FUV spectroscopy (R ~ 30,000-100,000) provided by HST/STIS occupies a unique observational parameter space that cannot be replaced by existing facilities. HST/STIS therefore remains essential for understanding the atmospheric physics and mass-loss processes of evolved stars. We highlight the need to preserve and prioritize high-resolution NUV and FUV spectroscopic capabilities with HST. Such programs would provide essential benchmarks for stellar atmosphere modeling, complement ongoing ALMA and optical observations, and help define future UV-optical capabilities for the Habitable Worlds Observatory (HWO).
title The unique capabilities of HST for stellar physics Probing Atmospheric Structure, Chromospheres, and Mass Loss of Evolved Stars
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2605.22956