Variable Stars in the Cetus dSph Galaxy: Population Gradients and Connections with the Star Formation History

Abstract

We investigate the variable star content of the isolated, Local Group, dwarf spheroidal galaxy (dSph) Cetus. Multi-epoch, wide-field images collected with the VLT/VIMOS camera allowed us to detect 638 variable stars (630 RR Lyrae stars and 8 Anomalous Cepheids), 475 of which are new detections. We present a full catalogue of periods, amplitudes, and mean magnitudes. Motivated by the recent discovery that the pulsational properties of the RR Lyrae stars in the Tucana dSph revealed the presence of a metallicity gradient within the oldest (>10 Gyr old) stellar populations, we investigated the possibility of an analogous effect in Cetus. We found that, despite the obvious radial gradient in the Horizontal Branch (HB) and Red Giant Branch (RGB) morphologies, both becoming bluer on average for increasing distance from the center of Cetus, the properties of the RR Lyrae stars are homogeneous within the investigated area (out to r~15'), with no significant evidence of a radial gradient. We discuss this in connection with the star formation history (SFH) previously derived for the two galaxies. The observed differences between these two systems show that even systems this small show a variety of early evolutionary histories. These differences could be due to different merger or accretion histories.

Accepted for publication on MNRAS. The complete set of light curves and finding charts, together with the full table of the pulsational properties of all variable stars will be available in the on-line edition of the paper

References in corpus (40)

• Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code
• Numerical Methods of Star Formation History Measurement and Applications to Seven Dwarf Spheroidals
• Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART
• The DART imaging and CaT survey of the Fornax Dwarf Spheroidal Galaxy
• Population Gradients in Local Group Dwarf Spheroidals
• The second and third parameters of the Horizontal Branch in Globular Clusters
• A multi-color and Fourier study of RR Lyrae variables in the globular cluster NGC 5272 (M3)
• Leo A: A Late-Blooming Survivor of the Epoch of Reionization in the Local Group
• The ACS LCID project. III. The star formation history of the Cetus dSph galaxy: a post-reionization fossil
• Observations and Implications of the Star Formation History of the LMC
• Structural parameters for the M31 dwarf spheroidals
• The ACS LCID project. V. The Star Formation History of the Dwarf Galaxy \objectname[]{LGS-3}: Clues for Cosmic Reionization and Feedback
• The ACS LCID project. VI. The SFH of the Tucana dSph and the relative ages of the isolated dSph galaxies
• The Helium abundance and Delta Y / Delta Z in Lower Main Sequence stars
• Nonlinear Investigation of the Pulsational Properties of RR Lyrae Variables
• Feedback and the Formation of Dwarf Galaxy Stellar Halos
• RR Lyrae stars in Galactic globular clusters.III. Pulsational predictions for metal content Z=0.0001 to Z=0.006
• IAC-pop: Finding the Star Formation History of Resolved Galaxies
• Life at the Periphery of the Local Group: the kinematics of the Tucana Dwarf Galaxy
• The Carina Project: II. Stellar Populations
• The ACS LCID Project. I. Short-Period Variables in the Isolated Dwarf Spheroidal Galaxies Cetus & Tucana
• Inside the whale: the structure and dynamics of the isolated Cetus dwarf spheroidal
• The Globular Cluster Omega Centauri and the Oosterhoff Dichotomy
• Old Main Sequence Turnoff Photometry in the Small Magellanic Cloud. II. Star Formation History and Its Spatial Gradients
• Updated pulsation models for anomalous Cepheids
• RR Lyrae variables in Galactic globular clusters: IV. Synthetic HB and RR Lyrae predictions
• The ACS LCID Project. II. Faint Variable Stars in the Isolated Dwarf Irregular Galaxy IC1613
• The Carina Project: I. Bright Variable Stars
• The Metallicity Dependence of the Fourier Components of RR Lyrae Light Curves is the Oosterhoff/Arp/Preston Period Ratio Effect in Disguise
• RR Lyrae stars in Galactic globular clusters. VI. The Period-Amplitude relation
• The ACS LCID Project: RR Lyrae stars as tracers of old population gradients in the isolated dwarf spheroidal galaxy Tucana
• The variable star population in Phoenix: coexistence of Anomalous and short-period Classical Cepheids, and detection of RR Lyrae variables
• The ACS LCID project VII: the blue stragglers population in the isolated dSph galaxies Cetus and Tucana
• Synthetic properties of bright metal-poor variables. II. BL Her stars
• Synthetic properties of bright metal-poor variables. I. "Anomalous" Cepheids
• Multiple stellar population in the Sextans dwarf spheroidal galaxy?
• The ACS LCID project IV: detection of the RGB bump in isolated galaxies of the Local Group
• Galactic Models and White Dwarf Populations
• Period Change Similarities among the RR Lyrae Variables in Oosterhoff I and Oosterhoff II Globular Systems
• Sub-Clustering Among Local Group Galaxies

Cited by in corpus (17)

• The ACS LCID project. IX. Imprints of the early Universe in the radial variation of the star formation history of dwarf galaxies
• Variable Stars in Local Group Galaxies. I: Tracing the Early Chemical Enrichment and Radial Gradients in the Sculptor dSph with RR Lyrae Stars
• The Progenitors of the Milky Way Stellar Halo: Big Bricks Favoured over Little Bricks
• Environmental Quenching of Low-Mass Field Galaxies
• Search for RR Lyrae stars in DES ultra-faint systems: Grus I, Kim 2, Phoenix II, and Grus II
• Stellar orbits and the survival of metallicity gradients in simulated dwarf galaxies
• The ACS LCID Project. VIII. The short-period Cepheids of Leo A
• The ISLAnds Project III: Variable Stars in Six Andromeda Dwarf Spheroidal Galaxies
• Toward an internally consistent astronomical distance scale
• Stellar chemo-kinematics of the Cetus dwarf spheroidal galaxy
• Chemical Compositions of Field and Globular Cluster RR Lyrae Stars: I. NGC 3201
• Solo Dwarfs I: Survey introduction and first results for the Sagittarius Dwarf Irregular Galaxy
• On the central helium-burning variable stars of the LeoI dwarf spheroidal galaxy
• The Carina Project. VI. The helium burning variable stars
• Homogeneous Photometry VI: Variable Stars in the Leo I Dwarf Spheroidal Galaxy
• Variable Stars in Local Group Galaxies. IV. RR Lyrae stars in the central regions of the low-density galaxy Crater II
• Metallicity Distribution Functions of Four Local Group dwarf galaxies