A Second Shell in the Fornax dSph Galaxy

Abstract

In the search for tidal structure in Galactic satellite systems, we have conducted a photometric survey over a 10 square degree area centred on the Fornax dSph galaxy. The survey was made in two colours, and the resulting colour-magnitude data were used as a mask to select candidate Fornax RGB stars, thereby increasing the contrast of Fornax stars to background sources in the outer regions. Previously, we reported the presence of a shell (age 2 Gyr) located towards the centre of Fornax. In this contribution we reveal a second shell, significantly larger than the first, located 1.3 degrees NW from the centre of Fornax, outside the nominal tidal radius. Moreover, the distribution of Fornax RGB stars reveals two lobes extending to the spatial limit of our survey, and aligned with the minor axis and with the two shells. These results support the hypothesis of a merger between Fornax and a gas-rich companion approximately 2 Gyr ago.

Four pages,accepted for the Publications of the Astronomical Society of Australia. Contribution the annual ASA meeting, Brisbane 2004

References in corpus (12)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• A Universal Density Profile from Hierarchical Clustering
• The Structure of Cold Dark Matter Halos
• Dark Matter Substructure in Galactic Halos
• Dwarf Galaxies of the Local Group
• The Metamorphosis of Tidally Stirred Dwarf Galaxies
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: IV. Modeling the Sagittarius Tidal Tails
• Simple dynamical models of the Sagittarius dwarf galaxy
• Shell Structure in the Fornax Dwarf Spheroidal Galaxy
• A Wide-Field Survey of the Fornax Dwarf Spheroidal Galaxy
• Absolute Proper Motion of the Fornax Dwarf Spheroidal Galaxy from Photographic and HST WFPC2 Data
• Mapping Substructures in Dark Matter Halos

Cited by in corpus (11)

• A high resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy
• Exploring Halo Substructure with Giant Stars X. Extended Dark Matter or Tidal Disruption?: The Case for the Leo I Dwarf Spheroidal Galaxy
• Spatial dependence of the Star Formation History in the Central Regions of the Fornax Dwarf Spheroidal Galaxy
• Deconstructing dwarf galaxies: a Suprime-Cam survey of Andromeda II
• Merger traces in the spatial distribution of stellar populations in the Fornax dSph galaxy
• Internal rotation of Milky Way dwarf spheroidal satellites with $Gaia$ Early Data Release 3
• Rotating stellar populations in the Fornax dSph galaxy
• First ground-based CCD proper motions for Fornax II: Final results
• The age-metallicity relationship in the Fornax spheroidal dwarf galaxy
• Shell galaxies: kinematical signature of shells, satellite galaxy disruption and dynamical friction
• Can tides explain the low dark matter density in Fornax?