Which of these is NOT typical of a condensing protostar?

A.magnetic fields producing polar flows
B.dusty disks around their equators
C.Herbig-Haro objects projecting a light year out in space
D.fusion of helium into carbon in their cores
E.more infrared than visible light given off from the cocoon of dust around the star

c

To determine which of the given options is NOT typical of a condensing protostar, we'll analyze each option:

A. Magnetic fields producing polar flows: During the process of star formation, condensing protostars often generate strong magnetic fields, which can create polar flows of material along the magnetic field lines. This is a typical characteristic of a protostar.

B. Dusty disks around their equators: As a protostar forms, it accretes material from its surrounding cloud. This material often forms a rotating disk around the protostar's equator, known as a protoplanetary disk. These dusty disks are common around protostars, so this option is typical of a condensing protostar.

C. Herbig-Haro objects projecting a light year out in space: Herbig-Haro (HH) objects are formed when jets of material expelled from a protostar collide with the surrounding gas and dust, generating shock waves that emit light. HH objects are commonly found around protostars and are indicative of ongoing star formation. This option is typical of a condensing protostar.

D. Fusion of helium into carbon in their cores: Once a protostar has reached the stage of burning hydrogen into helium in its core, it enters the main-sequence phase, during which it fuses hydrogen into helium. The fusion of helium into carbon occurs in more advanced stages of stellar evolution, not during the protostar phase. Therefore, this option is NOT typical of a condensing protostar.

E. More infrared than visible light given off from the cocoon of dust around the star: As a protostar forms, it is often surrounded by a cocoon of dust and gas. This cocoon absorbs and re-emits the star's radiation, resulting in an emission that is predominantly in the infrared portion of the electromagnetic spectrum. This option is typical of a condensing protostar.

Based on the explanations above, option D. fusion of helium into carbon in their cores is NOT typical of a condensing protostar.