Resolving Globular Clusters in NGC1399 with the Hubble Space Telescope (HST)

NGC 1399 is a giant elliptical cD galaxy composed of some 1012 stars which dominates the Fornax cluster, located at 20 Mpc from Earth. The image shown below represents a mosaic of 3x3 images obtained in 2005 with the Advanced Camera for Surveys on board of the Hubble Space Telescope. The large area of this detector allowed to sample a large region of 50x50 kpc centered on the galaxy.

Figure 1: The 3x3 mosaic of HST-ACS images centered on NGC 1399. The red color is produced artificially to enhance different objects in the field; the real image is monocromatic. The insets show details of different objects in the field. Click on the image for higher resolution

This image has been acquired within a project (G.O.10129) aimed at measuring accurately the sizes of the thousand of Globular Clusters that surround NGC1399, and compare their positions with those of X-ray sources. This kind of measurements are only possible with HST, since the angular resolution required is only archievable from space, where there is no interference from Earth's atmosphere. The paper with full details is now published on ApJ.

In the same field are also visible numerous satellite and background galaxies, revealing the variety of morphologies and properties which characterize these stellar systems. Note that the images shown here (also the higher resolution one) represent only a fraction of the full resolution of the original HST data which allows to study extremely small details.