A What is the dust-to-gas ratio in oxygen-poor galaxies?

[newgate]

Hello,
Assuming that dust is formed by silicates with Mg and Fe. What is the largest possible silicate dust-to-gas ratio in mass?

 

[davenn]

Hello,
Assuming that dust is formed by silicates with Mg and Fe. What is the largest possible silicate dust-to-gas ratio in mass?

hi

well since you have used an A tag, I assume you are a university post graduate.
What research have you do some far on this very vague topic you have posted ?

What dust to gas ratio are you talking about ?Dave

 

[newgate]

Hi Dave,
Now I'm just reading something about interstellar medium ISL and what I find is that the ISM constituted by gas and dust. The gas is mainly composed by hydrogen and helium and also small quantities of heavy elements! The dust is composed by small grains of solid materials namely silicates. And during lectures I faced "dust to gas ratio" but I don't know what is it and how to calculate it!

 

[newgate]

Any help?

 

[CWatters]

Not my field but Google can find papers with titles such as. "Variation between dust and gas in the diffuse interstellar medium". Seems to have lots of info on the methods used to measure and calculate the ratio.

 

[stefan r]

Hello,
Assuming that dust is formed by silicates with Mg and Fe. What is the largest possible silicate dust-to-gas ratio in mass?

I'll give this a non advanced answer.

The Earth and Moon exist. They have similar composition. After Theia collided with Earth there was a cloud of silicate material around earth. There would have been very little gas in that cloud.
Some photos like hubble's pillars of creation show material clumping together in space while also being subjected to an intense stellar radiation and wind. I can imagine there are many circumstances where small planetoids made of silicates are blown more slowly than gas molecules. That allows for high concentrations of silicates.
The zodiacal dust is low in gas.

There is no upper limit to the ratio.

 

[CygnusX-1]

See the feature article on oxygen-poor galaxies in the https://www.skyandtelescope.com/sky-and-telescope-magazine/inside-april-2018-issue/ issue of Sky & Telescope.

The dust-to-gas ratio varies with the metallicity of a galaxy. For giant galaxies, like the Milky Way, the dust-to-gas ratio is on the order of 1%. For the Magellanic Clouds, which are smaller than the Milky Way and thus more metal-poor, the dust-to-gas ratio is lower. And for the most metal-poor galaxies, such as I Zwicky 18, the dust-to-gas ratio is roughly 0.001%, as stated in the Sky & Telescope article, which also includes a color image of the galaxy. Note, though, that this percentage is somewhat uncertain.