A star is born when contracting gas and dust from a nebula become so dense and hot that nuclear fusion starts.
A star is called a protostar before it begins nuclear fusion in its core and officially becomes a star. During this stage, a protostar is formed from a collapsing cloud of gas and dust, as gravity pulls material together and heats up the core.
The basic idea is that the protostar contracts, under the influence of gravity, until it gets dense and hot enough to undergo nuclear fusion. You can find more details at the Wikipedia article "Protostar".
A newly formed star is called a protostar. This is the early stage of a star's life cycle when it is still accumulating mass from its surrounding gas and dust. Once a protostar reaches a critical mass and temperature, nuclear fusion begins and it becomes a fully-fledged star.
No, a protostar is basically the BEGINNING of a star's life cycle.
A star begins its life as a ball of gas and dust. Gravity pulls the gas and dust into a spere. As the sphere becomes denser, it gets hotter and eventually reaches temperature of about 10,000,000 Celsius in its center. As hydrogen combines into helium, energy is released in a precess called neclear fusion.
mass
it's a protostar
A star is called a protostar before it begins nuclear fusion in its core and officially becomes a star. During this stage, a protostar is formed from a collapsing cloud of gas and dust, as gravity pulls material together and heats up the core.
The actual FIRST STAR is impossible to say when it existed. In the normal evolution of a star it becomes a protostar first. The life of a protostar is about 150,000 years before it becomes a main sequence star. But in the Early universe it is hard to say what was happening. They could have formed in days weeks months or even hours.
The formation of a protostar from a nebula. As the protostar forms, it accretes more mass from the cloud and spins. As it gains more mass, it eventually becomes massive enough to ignite the core and become a star. The protostar is the first step in the evolution of any star.
Nuclear fusion. In the case of stars, it is often called nucleosynthesis.
A protostar is more like a stage previous to a star - before it ignites.
The basic idea is that the protostar contracts, under the influence of gravity, until it gets dense and hot enough to undergo nuclear fusion. You can find more details at the Wikipedia article "Protostar".
A protostar must reach about 10 million degrees Celsius for nuclear fusion to start in its core, triggering the transition into a true star. This marks the point where hydrogen atoms begin fusing into helium, releasing energy in the process. So, a protostar will become a full-fledged star after nuclear fusion begins at this temperature.
A protostar becomes balanced when the gravitational forces pulling matter inward are balanced by the outward pressure due to nuclear fusion at its core. This marks the transition from a contracting protostar to a stable star in the main sequence phase of its lifecycle.
A newly formed star is called a protostar. This is the early stage of a star's life cycle when it is still accumulating mass from its surrounding gas and dust. Once a protostar reaches a critical mass and temperature, nuclear fusion begins and it becomes a fully-fledged star.
A protostar is a star that is just beginning to form out of a stellar nebular (under gravity). The core of the gravitational collapse is getting more and more massive and is heating up as a result of the gravimetric contraction but has not yet reached the point where nucleosynthesis has begun in its core. It is when this happens that it becomes a star.