The DESI Y1 RR Lyrae Catalog. II. The Metallicity Dependency of Pulsational Properties, the Shape of the RR Lyrae Instability Strip, and Metal Rich RR Lyrae

@article{medina2026desi,
  title = {{The DESI Y1 RR Lyrae Catalog. II. The Metallicity Dependency of Pulsational Properties, the Shape of the RR Lyrae Instability Strip, and Metal Rich RR Lyrae}},
  author = {G. E. Medina and T. S. Li and C. Allende Prieto and L. Beraldo e Silva and A. Byström and R. G. Carlberg and S. E. Koposov and M. Lambert and J. R. Najita and C. Rockosi and N. Kizhuprakkat and A. H. Riley and J. Aguilar and S. Ahlen and D. Bianchi and D. Brooks and T. Claybaugh and A. P. Cooper and A. de la Macorra and A. Dey and P. Doel and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and G. Gutierrez and M. Ishak and R. Kehoe and T. Kisner and M. Landriau and L. Le Guillou and A. Meisner and R. Miquel and F. Prada and I. Pérez-Ràfols and G. Rossi and E. Sanchez and D. Schlegel and J. Silber and D. Sprayberry and G. Tarlé and B. A. Weaver and R. Zhou},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/ae78cb},
  eprint = {2505.10614},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05780317v1},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - The DESI Y1 RR Lyrae Catalog. II. The Metallicity Dependency of Pulsational Properties, the Shape of the RR Lyrae Instability Strip, and Metal Rich RR Lyrae
AU  - G. E. Medina
AU  - T. S. Li
AU  - C. Allende Prieto
AU  - L. Beraldo e Silva
AU  - A. Byström
AU  - R. G. Carlberg
AU  - S. E. Koposov
AU  - M. Lambert
AU  - J. R. Najita
AU  - C. Rockosi
AU  - N. Kizhuprakkat
AU  - A. H. Riley
AU  - J. Aguilar
AU  - S. Ahlen
AU  - D. Bianchi
AU  - D. Brooks
AU  - T. Claybaugh
AU  - A. P. Cooper
AU  - A. de la Macorra
AU  - A. Dey
AU  - P. Doel
AU  - J. E. Forero-Romero
AU  - E. Gaztañaga
AU  - S. Gontcho A Gontcho
AU  - G. Gutierrez
AU  - M. Ishak
AU  - R. Kehoe
AU  - T. Kisner
AU  - M. Landriau
AU  - L. Le Guillou
AU  - A. Meisner
AU  - R. Miquel
AU  - F. Prada
AU  - I. Pérez-Ràfols
AU  - G. Rossi
AU  - E. Sanchez
AU  - D. Schlegel
AU  - J. Silber
AU  - D. Sprayberry
AU  - G. Tarlé
AU  - B. A. Weaver
AU  - R. Zhou
PY  - 2026
DA  - 2026/10/01
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/ae78cb
UR  - https://hal.science/hal-05780317v1
AB  - RR Lyrae stars (RRLs) are valuable probes of both Milky Way assembly and stellar-evolution physics. Using a sample 6240 RRLs obtained in the first year of the Dark Energy Spectroscopic Instrument (DESI) survey, we investigate the metallicity of RRLs and its correlation with their pulsation properties. We find that (1) a clear correlation between period and [Fe/H] reinforces the view that the long-standing Oosterhoff dichotomy arises from the scarcity of intermediate-metallicity Galactic globular clusters hosting sizeable RRL samples; (2) high-amplitude short-period and small-amplitude short-period variables are comparatively metal-rich, with mean [Fe/H] = −1.39 ± 0.27 and −1.30 ± 0.28, respectively; (3) in double-mode pulsators (RRd), the metallicity declines smoothly with increasing fundamental-mode period, and anomalous RRd stars occupy a remarkably narrow [Fe/H] range relative to classical RRd stars; (4) this spectroscopic sample lets us, for the first time, place empirical constraints on the metallicity-dependent topology of the instability strip using phase-corrected effective temperatures and a large number of RRLs, where we observe an instability strip that moves towards cooler T eff with declining [Fe/H] with a width roughly consistent with stellar-evolution models; and (5) a subset of metal-rich RRLs exhibits orbits consistent with disk membership and halo kinematics. Our results confirm the tantalizing potential of DESI for Galactic and stellar astrophysics and highlight the importance of the even larger samples of RRLs and data-processing improvements forthcoming in future DESI data releases.
SN  - 0004-637X
SN  - 1538-4357
ER  -