A fresh look at the RR Lyrae population in the Draco dwarf spheroidal galaxy with Gaia

Abstract

We present a catalogue of 285 RR Lyrae stars (RRLs) in the Draco dwarf spheroidal galaxy (dSph), obtained by combining data from a number of different surveys including the second data release (DR2) of the European Space Agency (ESA) cornerstone mission Gaia. We have determined individual distances to the RRLs in our sample using for the first time a Gaia G-band luminosity-metallicity relation (MG - [Fe/H]) and study the structure of the Draco dSph as traced by its RRL population. We find that the RRLs located in the western/south-western region of Draco appear to be closer to us, which may be a clue of interaction between Draco and the Milky Way (MW). The average distance modulus of Draco measured with the RRLs is 19.53 +/- 0.07 mag, corresponding to a distance of 80.5 +/- 2.6 kpc, in good agreement with previous determinations in the literature. Based on the pulsation properties of the RRLs we confirm the Oosterhoff-intermediate nature of Draco. We present an additional sample of 41 candidate RRLs in Draco, which we selected from the Gaia DR2 catalogue based on the uncertainty of their G-band magnitudes. Additional epoch data that will become available in the Gaia third data release (DR3) will help to confirm whether these candidates are bona-fide Draco RRLs.

15 pages, 14 figures, 5 tables. Accepted for publication in MNRAS

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• Bayesian analysis of resolved stellar spectra: application to MMT/Hectochelle Observations of the Draco dwarf spheroidal
• Comparison of Distances from RR Lyrae Stars, the Tip of the Red-Giant Branch and Classical Cepheids
• Gaia Data Release 1 - The Cepheid & RR Lyrae star pipeline and its application to the south ecliptic pole region
• The Variable Stars of the Draco Dwarf Spheroidal Galaxy - Revisited
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• The infrared JHK light curves of RR Lyr
• Newly Discovered RR Lyrae Stars in the SDSSXPanXSTARRS1XCatalina Footprint
• Predicted properties of RR Lyrae stars in the SDSS photometric system

Cited by in corpus (10)

• Gaia early DR3 systemic motions of Local Group dwarf galaxies and orbital properties with a massive Large Magellanic Cloud
• RR Lyrae From Binary Evolution: Abundant, Young and Metal-Rich
• Timing the r-Process Enrichment of the Ultra-Faint Dwarf Galaxy Reticulum II
• HSTPROMO Internal Proper Motion Kinematics of Dwarf Spheroidal Galaxies: I. Velocity Anisotropy and Dark Matter Cusp Slope of Draco
• Stellar proper motions in the outskirts of classical dwarf spheroidal galaxies with Gaia EDR3
• On the Use of Field RR Lyrae as Galactic Probes. VI. Mixed mode RR Lyrae variables in Fornax and in nearby dwarf galaxies
• The VMC Survey -- LIV. Anomalous Cepheids in the Magellanic Clouds Period-Luminosity relations in the near-infrared bands
• The mass-metallicity relation at z>3 down to M_*= 10^4 M_Sun. A local perspective using the metallicity distribution of RR Lyrae stars
• Constraining the shape of Milky Way satellites with distance gradients
• rrlfe: Software for Generating and Applying Metallicity Calibrations for RR Lyrae Variable Stars Across a Wide Range of Phases and Temperatures