“metallicity”可以造什么句，metallicity造句

Because we see the galaxy when it was young, this result suggests spiral discs start off with steep metallicity gradients.

In this model, a mass of gas collapses and creates lots of stars at the disc's centre, where the stars quickly boost the metallicity.

Because stars congregate at a galaxy's centre, the metallicity in most nearby spirals is greatest there and drops toward the edge.

If astronomers could observe metallicity gradients in spiral galaxies billions of light-years away, we could see how steep the gradients were billions of years ago and thus how they change over time.

The metallicity of a star measures the amount of "metals" it has —that is, any element heavier than helium.

In addition, last year other astronomers reported a steep metallicity gradient in an even farther galaxy, but that galaxy is not a spiral, so its relevance to the Milky Way is less clear.

Benson says that the steep metallicity gradient agrees with the long-standing but unconfirmed idea that spiral galaxies form their discs of stars from the inside out.

Different theories predict how this metallicity gradient changes over billions of years.