What is a dark molecular cloud?

molecular cloud, also called dark nebula, interstellar clump or cloud that is opaque because of its internal dust grains. The form of such dark clouds is very irregular: they have no clearly defined outer boundaries and sometimes take on convoluted serpentine shapes because of turbulence.

How can molecules exist at the center of a dark cloud?

(7) These radio observations showed that the gas in the dark clouds was molecular in form, like the Earth’s atmosphere. For this reason, we can call dark clouds molecular clouds. (8) Molecules can exist in this part of space because the dust blocks the UV light.

What are cores of giant molecular clouds?

The cores of molecular clouds are the coldest regions of our Galaxy, with temperatures in the 8K to 20K range. These cores are also the densest regions of the interstellar medium, with the number of molecules exceeding 105 per cubic centimeter.

Do molecular clouds have dense cores?

Within molecular clouds are regions with higher density, where much dust and many gas cores reside, called clumps. These clumps are the beginning of star formation if gravitational forces are sufficient to cause the dust and gas to collapse.

What is the darkest cloud?

The dark clouds in space are called absorption nebulas or dark nebulas. An absorption nebula is a cloud of gas and dust which blocks light from the regions of space behind it.

What are dark nebulae made of?

Dark clouds appear so because of sub-micrometre-sized dust particles, coated with frozen carbon monoxide and nitrogen, which effectively block the passage of light at visible wavelengths.

What causes dark nebula?

What causes a dark nebula? They are caused by interstellar clouds with a very high concentration of dust grains obscuring light. These dust clouds obscure and block visible light objects behind it. Such as background stars or emission or reflection nebulae.

What happens when a molecular cloud core gets very dense?

Star formation begins when the denser parts of the cloud core collapse under their own weight/gravity. These cores typically have masses around 104 solar masses in the form of gas and dust. The cores are denser than the outer cloud, so they collapse first.

How do you identify molecular clouds?

It can be observed through rovibrational and fluorescent transitions, but only within environments which are very specific, such as shocks and regions containing high levels of ultraviolet emission. Therefore, the principal component of molecular clouds is effectively unmeasurable.

What nebula is Earth in?

The closest known nebula to Earth is called the Helix Nebula.