What is age-metallicity degeneracy?

What is age-metallicity degeneracy?

The optical colors of old populations are affected by the age-metallicity degeneracy (Worthey 1994): it implies that the spectrophotometric properties of an unresolved stellar population can not be distinguished from those of another population three times older and with half the metal content.

What is the relation to the age and metallicity?

The age-metallicity relation (AMR) is a fundamental observational constraint for understanding how the Galactic disc formed and evolved chemically in time.

Do older stars have lower metallicity?

It follows that older generations of stars, which formed in the metal-poor early Universe, generally have lower metallicities than those of younger generations, which formed in a more metal-rich Universe.

How is metallicity determined?

The metallicity was determined using synthetic spectral fitting of several atomic species. For M dwarfs that are cooler than 3575 K, the line strengths of FeH lines were used to determine the effective temperatures, while for warmer stars a photometric calibration was used.

How does metallicity affect opacity?

The metal- licity chiefly affects the opacity, or the amount of bound-free absorption, which only comes from metals. The smaller opacity allows the energy to escape more easily (so the star appears bluer).

How is metallicity calculated?

A different way of measuring a star’s chemical composition is by the Iron(Fe)-to-Hydrogen(H) ratio: for the sun, so that for every Iron atom there are 20,000 Hydrogen atoms. Question: What does it mean to have a metallicity: [Fe/H] = +1.0.

What is solar metallicity?

0.012Sun / Metallicity

What is meant by degeneracy of hydrogen?

Degeneracy of Hydrogen atom. In quantum mechanics, an energy level is said to be degenerate if it corresponds to two or more different measurable states of a quantum system. Conversely, two or more different states of a quantum mechanical system are said to be degenerate if they give the same value of energy upon measurement.

What is the degeneracy level of the hydrogen atom for n = 3?

My textbook stated that the degeneracy level of the hydrogen atom for n = 3 is 18. I’m trying to figure out why it’s true. I’m familiar with the Bohr’s module but I can’t seem to figure out how to does it help me to calculate it.

What is the metallicity of a population 1 star?

Young Population I stars have significantly higher iron-to-hydrogen ratios than older Population II stars. Primordial Population III stars are estimated to have a metallicity of less than −6.0, that is, less than a millionth of the abundance of iron in the Sun.

What is metallicity in the early universe?

Metallicity. It follows that older generations of stars, which formed in the metal-poor early Universe, generally have lower metallicities than those of younger generations, which formed in a more metal-rich Universe.