 Continuing to accumulate mass, its gravitational collapse causes the protostar's diameter to shrink significantly, and its core temperature rises to 5 million Kelvin. Some astronomers point out that this is hot enough for some hydrogen fusion in its core. This makes it a true star, but because it is still growing by accreting large amounts of material from its surroundings, it is not yet stable. Astronomers call these stars pre-main-sequence stars, or young stellar objects. During this phase, a strong solar wind forms pushing back on the gas and dust surrounding it. A typical transition for a star with three times the mass of our sun or less is through a T-Tari phase named after the star, T-Tari. The orange star at the center of this photograph is T-Tari. It's the prototype for the T-Tari class of variables. Here we see it surrounded by a dusty yellow cloud named the HINZ variable nebula. A typical characteristic of T-Tari stars are jets of high speed gas and dust streaming from both poles as strong magnetic fields guide matter from the star's circumstellar disk into the core. We can see these jets in star birth nebula. Here's a striking example from the Corayna nebula. You can see the jets at the top of this mystic mountain. Here's a view of a multiple star system called XZ-Tari. It's neighbor HL-Tari and V-1213-Tari, just 450 light years away. These young stellar objects are illuminating the entire region. XZ-Tari is actually a binary star system. It is expelling hot bubbles of gas into the surrounding space. Gas from an unseen disk around one or both of the stars is channeling through magnetic fields surrounding the binary system and forced out into space at nearly 540,000 kilometers per hour or 300,000 miles per hour. This outflow, which is only about 30 years old, extends nearly 96 billion kilometers or 60 billion miles from the star. Stars can remain in the T-Tari phase for as long as 100 million years and reach 10 million Kelvin at their cores. As their solar winds pick up, they disperse the remaining gas and dust around them back into the interstellar medium. This ends mass accumulation, and the star settles into hydrostatic equilibrium. At the mass of our sun, the core temperature reaches 15 million degrees Kelvin. And it has 99.8% of all the collapsing molecular cloud fragments matter, leaving only 0.2% left over for planets, moons, asteroids, and comets. It is now a main sequence star.