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Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or " star -forming regions", collapse and form stars. [1] As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to ...
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. The table shows the lifetimes of stars as a ...
A star-forming region in the Large Magellanic Cloud. A star is a luminous spheroid of plasma held together by self-gravity. [1] The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light.
Formation and evolution of the Solar System. Artist's conception of a protoplanetary disk. There is evidence that the formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. [1] Most of the collapsing mass collected in the center, forming the Sun, while the rest ...
Therefore, later generations of stars formed in this spiral disk. Most younger stars, including the Sun, are observed to be in the disk. Since the first stars began to form, the Milky Way has grown through both galaxy mergers (particularly early in the Milky Way's growth) and accretion of gas directly from the Galactic halo.
Stellar classification. In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines.
e. The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to ...
The primary objective of the Galaxy Evolution Explorer was to learn what factors trigger star formation inside galaxies; how quickly stars form, evolve and die; and how heavy chemical elements form in stars. Additional goals include: Determining how fast stars are forming inside each galaxy; Determining when and how the stars we see today formed