Which type of galaxy is most likely to have ongoing star formation?

Spiral galaxies are typically characterized by their distinct spiral arms and the presence of substantial amounts of gas and dust, which are the essential materials for star formation. In spiral galaxies, ongoing processes of star birth are observable, particularly in the regions within the arms where the density of gas is higher. This leads to the formation of new stars, often seen as luminous blue stars that indicate recent star formation activity.

While irregular galaxies also exhibit active star formation, the scale and organized structure of spirals often lead to more extensive regions of star formation. Dwarf galaxies, although they can have stars forming as well, are generally smaller and may not have the same continuous star-forming activity as seen in larger spirals. Elliptical galaxies, in contrast, predominantly consist of older stars and have very little gas, which results in minimal to no ongoing star formation. Thus, the characteristics of spiral galaxies make them the most likely candidates for having ongoing star formation compared to other galaxy types.