Stellar variability and distance indicators in the near-infrared in nearby galaxies. I. RR Lyrae and Anomalous Cepheids in Draco Dwarf spheroidal
The Draco Dwarf spheroidal (dSph) galaxy is one of the nearest and the most dark-matter-dominated satellites of the Milky Way. We obtained multiepoch near-infrared (NIR, JHK s ) observations of the central region of Draco dSph covering a sky area of ∼21′ × 21′ using the WIRCam instrument at the 3.6...
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| Main Authors: | , , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
30 April 2024
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| In: |
The astronomical journal
Year: 2024, Volume: 167, Issue: 5, Pages: 1-11 |
| ISSN: | 1538-3881 |
| DOI: | 10.3847/1538-3881/ad38b6 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.3847/1538-3881/ad38b6 Resolving-System, kostenfrei, Volltext: https://iopscience.iop.org/article/10.3847/1538-3881/ad38b6 
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| Author Notes: | Anupam Bhardwaj, Marina Rejkuba, Chow-Choong Ngeow, Marcella Marconi, Vincenzo Ripepi, Abhinna Sundar Samantaray, and Harinder P. Singh |
| Summary: | The Draco Dwarf spheroidal (dSph) galaxy is one of the nearest and the most dark-matter-dominated satellites of the Milky Way. We obtained multiepoch near-infrared (NIR, JHK s ) 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 JHK s time-series photometry for 212 RR Lyrae (173 fundamental-mode, 24 first-overtone, and 15 mixed-mode variables) and five Anomalous Cepheids in Draco dSph are 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 RRL = 19.557 ± 0.026 mag. The calibrated K s -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 Draco = 81.55 ± 0.98(statistical) ± 1.17(systematic) kpc, is the most accurate and precise distance to Draco dSph galaxy. |
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| Item Description: | Gesehen am 24.03.2025 |
| Physical Description: | Online Resource |
| ISSN: | 1538-3881 |
| DOI: | 10.3847/1538-3881/ad38b6 |