All You Need To Know About Stellar Halo

A galaxy's stellar halo is the portion of its galactic halo that contains stars. The halo is an area of a galaxy that is far from its brightest parts and usually has its oldest and metal-poorest stars.

 

•    Early investigations of the Milky Way's star halo's form discovered some indications that it might change with increasing distance from the galaxy.

 

•    These research discovered halos with flatter inner portions and spherically shaped outer regions.

 

•    In the twenty-first century, extensive surveys like the Sloan Digital Sky Survey have made it possible to analyze the structure and distribution of the stellar halo in great detail, this information has been used to postulate a triaxial or oblate halo.

 

•    The halo has been flattened with a broken power law radius dependency in more recent investigations, the existence of triaxiality is not clearly demonstrated.

 

•    Due to their dim brightness, star halos in distant galaxies have been difficult to observe, necessitating either extremely lengthy exposure times, the stacking of data from various galaxies to acquire averaged parameters, or observing only the resolved stellar populations. 

 

•    Only in the Milky Way and Andromeda can single resolved stars in stellar halos be measured. At a redshift distance of 1, the furthest star haloes have been found.

 

•    Galaxies expand through mergers according to the universe's Lambda-CDM model. A few of these streams are seen around the Milky Way. Streams of stars from broken satellite galaxies are discernible through their coherence in space or velocity. Such mergers are the reason for the substructure seen in the stellar halo of galaxies. Variations in star population features, like as metallicity, are evident in halos due to the accumulation from a variety of satellite galaxies.

 

•    According to astrophysical simulations of galaxies, stellar halos should consist of two parts: an inner region that is mostly made up of stars that formed inside the galaxy and an outer zone that is mainly made up of stars that were added during merger events. 

 

•    These components are predicted to have various structures and rotational axes. Although disputed, observational proof of this split halo in the Milky Way has been asserted.

 

•    According to research on the Milky Way galaxy, the stellar halo, which stretches beyond 100 kilo parsecs from the galactic center, holds between 0.1 and 1% of the galaxy's total star mass.