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A protostar is a very young star that is still gathering mass from its parent molecular cloud. It is the earliest phase in the process of stellar evolution. [1]
A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence.Earlier in its life, the object is a protostar that grows by acquiring mass from its surrounding envelope of interstellar dust and gas.
A protostar continues to grow by accretion of gas and dust from the molecular cloud, becoming a pre-main-sequence star as it reaches its final mass. Further development is determined by its mass. Mass is typically compared to the mass of the Sun: 1.0 M ☉ (2.0 × 10 30 kg) means 1 solar mass.
The combination of convection within the protostar and radiation from its exterior allow the star to contract further. [30] This continues until the gas is hot enough for the internal pressure to support the protostar against further gravitational collapse—a state called hydrostatic equilibrium.
A star forms by accumulation of material that falls in to a protostar from a circumstellar disk or envelope. Material in the disk is cooler than the surface of the protostar, so it radiates at longer wavelengths of light producing excess infrared emission. As material in the disk is depleted, the infrared excess decreases.
It is theorized that these proplyds are in a race with each other. The first one to form will become a protostar, which are very violent objects and will disrupt other proplyds in the vicinity, stripping them of their gas. The victim proplyds will then probably go on to become main-sequence stars or brown dwarfs of the L and T classes, which ...
When a protostar is formed from the collapse of a giant molecular cloud of gas and dust in the local interstellar medium, the initial composition is homogeneous throughout, consisting of about 70% hydrogen, 28% helium, and trace amounts of other elements, by mass. [11] The initial mass of the star depends on the local conditions within the cloud.
At this stage, a protostar is formed and it will continue to aggregate gas and dust from the cloud around it. One of the most studied star formation regions is the Taurus molecular cloud due to its close proximity to earth (140 pc or 430 ly away), making it an excellent object to collect data about the relationship between molecular clouds and ...