Maharashtra Class 8 Answered

How is a nebula formed and how do stars such as sun use hydrogen/helium? Plz explain the reaction.

Asked by vinaayakgaikwad | 12 Nov, 2018, 03:23: PM

Expert Answer

A planetary nebula is created when a star blows off its outer layers after it has run out of fuel to burn.

These outer layers of gas expand into space, forming a nebula which is often the shape of a ring or bubble.

The Sun or a star generates its energy by nuclear fusion of hydrogen nuclei into helium.

The basic Hydrogen fusion cycle involves four Hydrogen nuclei (protons) and two electrons

and yields a Helium nucleus, two neutrinos and six photons.

This process occurs in three steps: the first one is the Fusion of Hydrogen into Deuterium.

Here two protons collide, one proton turns into a neutron emitting an antielectron and a neutrino.

The remaining proton is bound to the neutron forming a heavy Hydrogen (Deuterium) nucleus while the antielectron just produced will annihilate with an electron generating two high-energy photons.

The second step is the the formation of Helium-3: A proton is captured by a nucleus of Deuterium emitting a photon and forming then a ³He nucleus.

The third step is recombination of two Helium-3 into one nucleus of Helium with the emission of two protons.

Steps 1 and 2 each happen twice for each time step 3 occurs. In this process the total net energy released is 26 MeV.

Answered by Thiyagarajan K | 13 Nov, 2018, 02:24: AM

Maharashtra Class 8 Answered

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Maharashtra Class 8 Answered

Concept Videos

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