Description: A protostar is an early stage in the star formation process. It is a large mass of gas and dust formed as a result of the contraction of a giant molecular cloud in the interstellar medium. As the cloud collapses, gravitational energy is converted into heat, warming the still-forming protostar. This phase may take anywhere from 10⁵ to 10⁷ years, depending on the mass of the star, with more massive stars forming more quickly. It begins with an increase in density in the molecular cloud core and ends with the formation of a pre-main-sequence star. Pre-main-sequence stars of similar mass to the Sun are known as T-Tauri stars. Once hydrogen fusion ignites in the core of a star it begins producing energy and becomes a main sequence star.

Related Terms:

• Main Sequence
• Star Formation
• Interstellar Medium
• Molecular Cloud

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

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