2024/04/01 by Anupam Bhardwaj, M. Rejkuba, Bhardwaj, Anupam +11 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2404.01394
openalex publication_date 2024/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Draco dwarf Spheroidal galaxy (dSph) is one of the nearest and the most dark matter dominated satellites of the Milky Way. We obtained multi-epoch near-infrared (NIR, JHKs) observations of the central region of Draco dSph covering a sky area of ∼ 21'×21' using the WIRCam instrument at the 3.6-m Canada-France-Hawaii Telescope. Homogeneous JHKs time-series photometry for 212 RR Lyrae (173 fundamental-mode, 24 first-overtone, and 15 mixed-mode variables) and 5 Anomalous Cepheids in Draco dSph is presented and used to derive their period-luminosity relations at NIR wavelengths for the first-time. The small scatter of ∼ 0.05~mag in these empirical relations for RR Lyrae stars is consistent with those in globular clusters and suggests a very small metallicity spread, up to ∼0.2~dex, among these centrally located variables. Based on empirically calibrated NIR period-luminosity-metallicity relations for RR Lyrae in globular clusters, we determined a distance modulus to Draco dSph of μ_\textrmRRL = 19.557 ± 0.026 mag. The calibrated Ks-band period-luminosity relations for Anomalous Cepheids in the Draco dSph and the Large Magellanic Cloud exhibit statistically consistent slopes but systematically different zero-points, hinting at possible metallicity dependence of ∼-0.3 mag~dex-1. Finally, the apparent magnitudes of the tip of the red giant branch in I and J bands also agree well with their absolute calibrations with the adopted RR Lyrae distance to Draco. Our recommended ∼1.5% precise RR Lyrae distance, D_\textrmDraco = 81.55 ± 0.98 \textrm(statistical) ± 1.17 \textrm(systematic)~kpc, is the most accurate and precise distance to Draco dSph galaxy.