Star clusters in the dwarf irregular galaxy Leo A

Abstract

Leo A is an isolated gas-rich dwarf irregular galaxy of low stellar mass and metallicity residing at the outskirts of the Local Group. Ages of the stellar populations in Leo A range from $\sim$10 Myr to $\sim$10 Gyr. So far, only one star cluster has been discovered in this galaxy. Our aim is to search for star cluster candidates in the Leo A galaxy. We performed photometry of star-like objects on HST ACS archive observation frames in the $F475W$ and $F814W$ passbands and studied the spatial clustering of the Leo A stars down to the turn-off point of the old stellar populations. We report the discovery of four star clusters in the Leo A galaxy. This means that now a sample of five star clusters is known in Leo A. Two clusters are of a young age ($\sim$20 Myr; overlapping with HII regions) and low in mass ($\gtrsim$400 M${}_{\odot }$ and $\gtrsim$150 M${}_{\odot }$), the other three clusters are older ($\gtrsim$100 Myr) and also of low mass ($\gtrsim$300 M${}_{\odot }$). These rough estimates are made assuming the isochrones of a metallicity derived for HII regions ($Z=0.0007$). Colour-magnitude diagrams of the stars residing in the circular areas of a 2.5arcsec radius around the clusters and integrated aperture photometry results of the clusters are presented.

arXiv comment5 pages, 3 figures, 2 tables, accepted for publication in A&A

References in corpus (24)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Dwarf Galaxies of the Local Group
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• WFPC2 Stellar Photometry with HSTphot
• Little Things
• Leo A: A Late-Blooming Survivor of the Epoch of Reionization in the Local Group
• WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group
• Variable Stars in Leo A: RR Lyraes, Short-period Cepheids, and Implications on Stellar Content
• Oxygen and Nitrogen in Leo A and GR 8
• PHAT Stellar Cluster Survey I. Year 1 Catalog and Integrated Photometry
• Chemistry and Kinematics of the Late-Forming Dwarf Irregular Galaxies Leo A, Aquarius, and Sagittarius DIG
• Full-Fledged Dwarf Irregular Galaxy Leo A
• Star Cluster Catalogs for the LEGUS Dwarf Galaxies
• Star Clusters in Evolving Galaxies
• The Star Clusters of the Small Magellanic Cloud: Structural Parameters
• An extended star cluster at the outer edge of the spiral galaxy M33
• The ACS LCID Project. VIII. The short-period Cepheids of Leo A
• Stellar Velocity Dispersion of the Leo A Dwarf Galaxy
• The Oldest Stars of the Extremely Metal-Poor Local Group Dwarf Irregular Galaxy Leo A
• Deriving physical parameters of unresolved star clusters. II. The degeneracies of age, mass, extinction, and metallicity
• Dwarf Irregular Galaxy Leo A. Suprime-Cam Wide-Field Stellar Photometry
• A Survey of Star Clusters in the M31 South-West Field. UBVRI Photometry and Multi-Band Maps
• Chemistry in the dIrr galaxy Leo A

Cited by in corpus (1)

• The ionization structure and chemical history in isolated H ii regions of dwarf galaxies with VIMOS/IFU II. The Leo A galaxy