The Age and Metallicity of the Bootes I System

Abstract

We present Washington photometry of a field central to the Bootes I dwarf spheroidal galaxy, which was discovered as a stellar overdensity in the Sloan Digital Sky Survey (DR5). We show that the Washington filters are much more effective than the Sloan filters in separating the metal-poor turn-off stars in the dwarf galaxy from the foreground stars. We detect 165 objects in the field, and statistically determine that just over 40% of the objects are non-members. Our statistical analysis mostly agrees with radial velocity measurements of the brighter stars. We find that that there is a distinct main-sequence turn-off and subgiant branch, where there is some evidence of a spread in chemical abundance. Any evidence of an age spread is limited to a few billion years. The brightest 7 Bootes I members give a (photometric-color derived) weighted mean iron-abundance of [Fe/H]=-2.1+/-0.4, and the best-fit isochrone is the 14.1 Gyr, Z=0.0002 model, with DM=19.11 and E(B-V)=0.02.

arXiv comment20 pages, 7 figures, to appear in the AJ

References in corpus (25)

• The Sloan Digital Sky Survey: Technical Summary
• Evolution of asymptotic giant branch stars II. Optical to far-infrared isochrones with improved TP-AGB models
• The Field of Streams: Sagittarius and its Siblings
• Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code
• Abundances for Globular Cluster Giants: I. Homogeneous Metallicities for 24 Clusters
• A New Milky Way Dwarf Galaxy in Ursa Major
• A Faint New Milky Way Satellite in Bootes
• Scaled solar tracks and isochrones in a large region of the Z-Y plane I. From the ZAMS to the TP-AGB end for 0.15 - 2.5 Mo stars
• A New Milky Way Dwarf Satellite in Canes Venatici
• A New Milky Way Companion: Unusual Globular Cluster or Extreme Dwarf Satellite?
• A Curious New Milky Way Satellite in Ursa Major
• A Keck/DEIMOS spectroscopic survey of faint Galactic satellites: searching for the least massive dwarf galaxies
• A Pair of Bootes: A New Milky Way Satellite
• WFPC2 Observations of Star Clusters in the Magellanic Clouds. II. The Oldest Star Clusters in the Small Magellanic Cloud
• Exploring Halo Substructure with Giant Stars: The Dynamics and Metallicity of the Dwarf Spheroidal in Bootes
• Variable stars in the newly discovered Milky Way satellite in Bootes
• The pure non-collisional Blue Straggler population in the giant stellar system omega Centauri
• The blue plume population in dwarf spheroidal galaxies: genuine blue stragglers or young stellar population?
• RR Lyrae Stars in the Bootes dSph
• Standard Giant Branches in the Washington Photometric System
• Numerical Color-Magnitude Diagram Analysis of SDSS Data and Application to the New Milky Way satellites
• A Constraint on Z_\odot from Fits of Isochrones to the Color-Magnitude Diagram of M67
• Trimming Down the Willman 1 dSph
• Absence of HI in the Bootes Dwarf Spheroidal Galaxy
• uvbyCa H beta CCD Photometry of Clusters. VII. The Intermediate-Age Anticenter Cluster Melotte 71

Cited by in corpus (9)

• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• Accurate Stellar Kinematics at Faint Magnitudes: application to the Bootes~I dwarf spheroidal galaxy
• Leo P: An Unquenched Very Low-Mass Galaxy
• The [Fe/H], [C/Fe], and [alpha/Fe] distributions of the Bootes I Dwarf Spheroidal Galaxy
• The chemical evolution of the Bootes I ultra-faint dwarf galaxy
• Chemical enrichment in very low-metallicity environments: Bootes I
• Stellar Density Profiles of Dwarf Spheroidal Galaxies
• Photometric Metallicities in Bootes I
• A Multi-Wavelength Study of the Segue 3 Cluster