On the radial extent of the dwarf irregular galaxy IC10

Abstract

We present new deep and accurate space (Advanced Camera for Surveys -- Wide Field Planetary Camera 2 at the Hubble Space Telescope) and ground-based (Suprime-Cam at Subaru Telescope, Mega-Cam at Canada-France-Hawaii Telescope) photometric and astrometric data for the Local Group dwarf irregular IC10. We confirm the significant decrease of the young stellar population when moving from the center toward the outermost regions. We find that the tidal radius of IC10 is significantly larger than previous estimates of $r_t\lesssim$ 10\min. By using the $I$,\vmi\ Color Magnitude Diagram based on the Suprime-Cam data we detect sizable samples of red giant (RG) stars up to radial distances of 18-23${}^{\prime }$ from the galactic center. The ratio between observed star counts (Mega-Cam data) across the tip of the RG branch and star counts predicted by Galactic models indicate a star count excess at least at a 3$\sigma$ level up to 34-42\min\ from the center. This finding supports the hypothesis that the huge H{\size{I}} cloud covering more than one degree across the galaxy is associated with IC10 \citep{huchtmeier79,cohen79}. We also provide new estimates of the total luminosity ($L_V\sim 9\times$$10^7$ $L_{\odot }$, $M_V$$\sim$-15.1 mag) that agrees with similar estimates available in the literature. If we restrict to the regions where rotational velocity measurements are available (r$\approx 13^{\prime }$), we find a mass-to-light ratio ($\sim$10 $M_{\odot }$ $L_{\odot }$) that is at least one order of magnitude larger than previous estimates. The new estimate should be cautiously treated, since it is based on a minimal fraction of the body of the galaxy.

7 pages, 4 figures, ApJ Letters accepted

References in corpus (6)

• Scaling Relations and the Fundamental Line of the Local Group Dwarf Galaxies
• A trio of new Local Group galaxies with extreme properties
• Formation of blue compact dwarf galaxies from merging and interacting gas-rich dwarfs
• Recovering the star formation rate in the solar neighborhood
• On the distance and reddening of the starburst galaxy IC10
• On the stellar content of the starburst galaxy IC10

Cited by in corpus (16)

• The Next Generation Virgo Cluster Survey (NGVS). XIII. The Luminosity and Mass Function of Galaxies in the Core of the Virgo Cluster and the Contribution from Disrupted Satellites
• Evidence for an Interaction in the Nearest Starbursting Dwarf Irregular Galaxy IC 10
• DUSTiNGS III: Distribution of Intermediate-Age and Old Stellar Populations in Disks and Outer Extremities of Dwarf Galaxies
• The extended structure of the dwarf irregular galaxies Sextans A and Sextans B. Signatures of tidal distortion in the outskirts of the Local Group
• The HI Chronicles of LITTLE THINGS BCDs II: The Origin of IC 10's HI Structure
• The Carina Project. X. On the kinematics of old and intermediate-age stellar populations
• The Star Cluster System in the Local Group Starburst Galaxy IC 10
• Towards a census of the Galactic anticentre star clusters - III: tracing the spiral structure in the Outer Disk
• The red extended structure of IC10, the nearest blue compact galaxy
• Relationships between the Stellar, Gaseous, and Star Formation Disks in LITTLE THINGS Dwarf Irregular Galaxies: Indirect Evidence for Substantial Fractions of Dark Molecular Gas
• Solo dwarfs IV: Comparing and contrasting satellite and isolated dwarf galaxies in the Local Group
• The extended structure of the dwarf irregular galaxy Sagittarius
• The Carina Project VII: Towards the breaking of the age-metallicity degeneracy of red giant branch stars using the c_UBI index
• A kinematic study of planetary nebulae in the dwarf irregular galaxy IC10
• Outskirts of Nearby Disk Galaxies: Star Formation and Stellar Populations
• Euclid: Early Release Observations -- The star cluster systems of the Local Group dwarf galaxies IC 10 and NGC 6822