ellipsigalaksityyppejä

Ellipsigalaksityypit refers to the classification of elliptical galaxies based on their apparent shape. This system, a part of the Yerkes spectral classification, categorizes elliptical galaxies from E0 to E7. The number assigned to an elliptical galaxy indicates its degree of flattening, with E0 galaxies being the most spherical and E7 galaxies being the most flattened or elongated.

The classification is determined by observing the galaxy's projected shape on the sky. An E0 galaxy appears almost perfectly circular, while an E7 galaxy is noticeably elongated. The intermediate types, E1 through E6, represent a continuous range of apparent elongations between these two extremes. It's important to note that this classification is based on the visual appearance and doesn't necessarily reflect the galaxy's true three-dimensional shape, as the observed flattening can be influenced by the observer's viewing angle.

Elliptical galaxies are generally characterized by their smooth, featureless appearance and a population of older, redder stars. They typically contain little gas and dust and exhibit very little ongoing star formation. The E0 to E7 classification helps astronomers study the distribution and evolution of these galaxies, as the degree of flattening can be related to factors such as the galaxy's formation history, its internal dynamics, and its interactions with other galaxies. While the basic E0-E7 scheme is widely used, further subdivisions and more complex classification systems exist to capture finer details of galactic morphology.