Astronomers Detect an Extended Stellar Halo Surrounding Galaxy Ark 227
Ark 227 is a dwarf galaxy with an elliptical morphology, located about 85-114 million light-years from Earth. Prior to the JWST observations, astronomers had only detected stars within the central region of Ark 227. However, the JWST observations revealed that Ark 227 is surrounded by a vast stellar halo that extends to distances of up to 100,000 light-years from the galaxy's center.
The astronomers also identified one or possibly two accretion shelves within the stellar halo of Ark 227. Accretion shelves are structures that are thought to form when dwarf galaxies merge with other galaxies. The presence of accretion shelves in the stellar halo of Ark 227 suggests that the galaxy has experienced at least two minor mergers in its past.
The discovery of an extended stellar halo around Ark 227 is significant because it provides new evidence for the hierarchical growth of galaxies. According to the hierarchical model of galaxy formation, large galaxies form through the accretion of smaller galaxies. The discovery of an extended stellar halo around Ark 227 suggests that dwarf galaxies play an important role in the formation of larger galaxies.
The JWST observations of Ark 227 also demonstrate the telescope's ability to detect faint stars at great distances. This capability will enable astronomers to study the stellar halos of other dwarf galaxies in more detail, which will provide new insights into the formation and evolution of these galaxies.