Ababy star that is still gathering mass in a nebula and has not begun fusion is called

The star is called protostar.

Explanation:

A protostar is a youthful star that is as yet assembling mass from its parent sub-atomic cloud. The protostellar stage is the most punctual one during the time spent outstanding evolution. For a low mass star (for example that of the Sun or lower), it keeps going around 500,000 years.

The stage starts when an atomic cloud part first falls under the power of self-gravity; and an obscure and weight bolstered center structures inside the crumbling section. It closes when the infalling gas is drained, leaving a pre-principle arrangement star, which agreements to later turn into a fundamental grouping star at the beginning of hydrogen combination.

it restores trees to areas where they once grew.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.