The Treasury of Extremely Metal-Poor O Stars
Abstract
The Treasury of Extremely Metal-Poor O Stars (TEMPOS) is a Hubble Space Telescope survey of hot and massive O-type stars in nearby, low-metallicity galaxies (≲20% of the solar metallicity, Z⊙). Understanding massive-star physics in this regime is essential to interpret observations of metal-poor galaxies, including both low-mass dwarf galaxies and chemically unevolved galaxies in the early Universe. Yet, few far-ultraviolet (FUV) spectra of O stars of sufficient quality to characterize their fundamental properties and stellar winds exist below 20% Z⊙, and heterogeneous observation design and incomplete coverage of parameter space pose significant barriers to progress. To remedy this, TEMPOS obtained new Cosmic Origins Spectrograph (COS) FUV spectra of 12 very metal-poor O stars, building upon archival data to assemble a spectroscopic atlas of 29 homogeneously observed stars that efficiently samples a wide range of spectral types and luminosity classes. Here, we describe the motivation, sample selection, and observation design for TEMPOS and present the first data release of reduced and coadded COS spectra. We then present initial results on the empirical properties of FUV O-star spectra below 20% Z⊙, including radial velocities, equivalent widths of photospheric lines, and terminal wind velocities (v∞). We show that v∞ correlates with host galaxy metallicity across ∼5-50% Z⊙ and find tentative evidence of a steeper decline in wind strength below ∼10% Z⊙. The combined dataset of FUV spectra and planned releases of photometry and optical spectra from the TEMPOS Treasury program will advance our understanding of both stellar astrophysics and the interstellar medium in the extremely metal-poor regime.
Versions
Related
- Abundance analysis of three new extremely metal-poor stars, including one CEMP-s star
- Ionised gas kinematics and star-forming clumps in extremely metal-poor galaxies
- Nebular Spectra of the Extremely Metal-Poor SN II 2023ufx Over a Year After Explosion: A Massive Progenitor and Unique Circumstellar Environment
- High-resolution Spectroscopic Follow-up Observation Results for 13 Extremely Metal-poor Candidates Selected by Narrowband Photometry
- Ionized Gas Kinematics and Star-forming Clumps in Extremely Metal-poor Galaxies
BibTeX
@misc{telford2026treasury,
title = {{The Treasury of Extremely Metal-Poor O Stars}},
author = {O. Grace Telford and Christiana Erba and Kristen B. W. McQuinn and Calum Hawcroft and Andreas A. C. Sander and Julia Roman-Duval and John Chisholm and Danielle A. Berg and Varsha Ramachandran and Yong Zheng and Claus Leitherer and Abby Mintz and Evan N. Kirby},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.20928},
eprint = {2609.20928},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.20928},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Treasury of Extremely Metal-Poor O Stars
AU - O. Grace Telford
AU - Christiana Erba
AU - Kristen B. W. McQuinn
AU - Calum Hawcroft
AU - Andreas A. C. Sander
AU - Julia Roman-Duval
AU - John Chisholm
AU - Danielle A. Berg
AU - Varsha Ramachandran
AU - Yong Zheng
AU - Claus Leitherer
AU - Abby Mintz
AU - Evan N. Kirby
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.20928
UR - https://arxiv.org/abs/2609.20928
AB - The Treasury of Extremely Metal-Poor O Stars (TEMPOS) is a Hubble Space Telescope survey of hot and massive O-type stars in nearby, low-metallicity galaxies (≲20% of the solar metallicity, Z_⊙). Understanding massive-star physics in this regime is essential to interpret observations of metal-poor galaxies, including both low-mass dwarf galaxies and chemically unevolved galaxies in the early Universe. Yet, few far-ultraviolet (FUV) spectra of O stars of sufficient quality to characterize their fundamental properties and stellar winds exist below 20% Z_⊙, and heterogeneous observation design and incomplete coverage of parameter space pose significant barriers to progress. To remedy this, TEMPOS obtained new Cosmic Origins Spectrograph (COS) FUV spectra of 12 very metal-poor O stars, building upon archival data to assemble a spectroscopic atlas of 29 homogeneously observed stars that efficiently samples a wide range of spectral types and luminosity classes. Here, we describe the motivation, sample selection, and observation design for TEMPOS and present the first data release of reduced and coadded COS spectra. We then present initial results on the empirical properties of FUV O-star spectra below 20% Z_⊙, including radial velocities, equivalent widths of photospheric lines, and terminal wind velocities (v_∞). We show that v_∞ correlates with host galaxy metallicity across ∼5-50% Z_⊙ and find tentative evidence of a steeper decline in wind strength below ∼10% Z_⊙. The combined dataset of FUV spectra and planned releases of photometry and optical spectra from the TEMPOS Treasury program will advance our understanding of both stellar astrophysics and the interstellar medium in the extremely metal-poor regime.
ER -