# What is the density of the Carina Nebula?

• ozipin
In summary: This is not unreasonable, as the nebula is about 3,500 ly away from the sun. Sure - the reddit poster translated the column densities into a density range on an assumption that the nebula was about 15ly deep from our perspective. This is not unreasonable, as the nebula is about 3,500 ly away from the sun.
ozipin
In a James Webb photo thread, someone posted that the Carina Nebula has a density of a few atoms per cubic meter. This seems off to me, as this is close to the average density of the intergalactic medium of one atom per cubic meter, which is much less than the interstellar medium average density of one atom per cubic centimeter, which is much less than the average density of a planetary nebular (100-10,000 atoms per cubic centimeter). But I can't find any information on the web to help me understand this better.

Delta2
Moderator's note: Thread moved to astronomy forum.

I believe the Carina nebula is what is called a Giant Molecular Cloud (GMC). The Wikipedia article says the following: "Whereas the average density in the solar vicinity is one particle per cubic centimetre, the average density of a GMC is a hundred to a thousand times as great." The value of one atom/cubic meter is about the average mass density of the universe as a whole, so is much too low for even the vicinity of the sun, let alone a dense nebula like Carina.

For a more scholarly reference, this paper has the following quote, "By terrestrial standards, the interstellar matter is exceedingly tenuous: in the vicinity of the Sun, its density varies from ∼ 1.5 × 10−26 g cm−3 in the hot medium to ∼ 2 × 10−20 − 2 × 10−18 g cm−3 in the densest molecular regions, with an average of about 2.7 × 10−24 g cm−3 (see next subsections). This mass density, which corresponds to approximately one hydrogen atom per cubic centimeter, is over twenty orders of magnitude smaller than in the Earth’s lower atmosphere."

Ibix said:
which gives column densities
Translating column density to density requires some specialist knowledge, though. I'm not sure it helps the OP by itself.

Bandersnatch said:
Translating column density to density requires some specialist knowledge, though. I'm not sure it helps the OP by itself.
Sure - the reddit poster translated the column densities into a density range on an assumption that the nebula was about 15ly deep from our perspective.

## 1. What is density?

Density is a measure of how much mass is contained in a given volume. It is typically expressed in units of mass per unit volume, such as grams per cubic centimeter or kilograms per cubic meter.

## 2. How is density measured?

Density can be measured by dividing the mass of an object by its volume. In the case of the Carina Nebula, scientists use telescopes and other instruments to gather data on the mass and volume of the nebula in order to calculate its density.

## 3. What is the density of the Carina Nebula?

The density of the Carina Nebula varies depending on the specific region being observed. However, on average, it is estimated to be around 10,000 particles per cubic centimeter. This is much lower than the density of Earth's atmosphere, which is about 10^19 particles per cubic centimeter.

## 4. How does the density of the Carina Nebula compare to other nebulae?

The density of the Carina Nebula is considered to be relatively high compared to other nebulae. For example, the Orion Nebula has a density of about 100 particles per cubic centimeter, while the Eagle Nebula has a density of about 1 particle per cubic centimeter.

## 5. How does the density of the Carina Nebula affect its formation and evolution?

The high density of the Carina Nebula plays a significant role in its formation and evolution. The dense gas and dust within the nebula allows for the formation of new stars, and the high density also leads to intense radiation and stellar winds, shaping the structure of the nebula over time.

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