What is a metal poor star?

Published by Charlie Davidson on

What is a metal poor star?

Metal-poor stars that are observable today are PopulationII objects and belong to the stellar generations that formed from non-zero metallicity gas. In their atmospheres these objects preserve informa- tion about the chemical composition of their birth cloud.

Why are old stars metal poor?

The presence of heavier elements hails from stellar nucleosynthesis, where the majority of elements heavier than hydrogen and helium in the Universe (metals, hereafter) are formed in the cores of stars as they evolve. These became commonly known as Population I (metal-rich) and Population II (metal-poor) stars.

Are metal rich stars old?

We find that there do exist very metal-rich stars that are older than 10 Gyr. This is contrary to what is found in several recent studies of the galactic age-metallicity relation. This is tentative evidence that there might not exist a one-to-one relation between age and metallicity for all stars.

Why are metal rich stars redder?

We discussed this before: if the atmosphere of a star contains more metals, then the dust and the gas will scatter preferentially the blue light hence the stars appears redder.

Where are metal-poor stars found?

A true first star has not yet been discovered, although stars2,3,4 with tiny amounts of elements heavier than helium (‘metals’) have been found in the outer regions (‘halo’) of the Milky Way.

Why are metal-poor stars bluer?

Why? Line blanketing: lots of metals (particularly Fe) in the atmospheres of stars absorb preferentially blue light, so the star looks a bit redder.

Where are metal poor stars found?

Why are metal poor stars bluer?

Where are the most metal rich stars found in the Milky Way?

The most metal rich stars in the inner Galaxy are concentrated to the plane and the more metal poor stars are found predominantly further from the plane, with an overall vertical gradient in the mean of the MDF of about -0.45 dex/kpc.

Is our sun metal rich?

The Earth’s Sun is an example of a metal-rich star and is considered as an intermediate Population I star, while the solar-like Mu Arae is much richer in metals.

Are blue stars more metallic?

Age (young stars are blue) Metallicity (metal rich stars are redder than metal poor stars) Dust (reddens stars)…Stellar Populations.

Population I Population II
metal rich [Fe/H] > -1 metal poor [Fe/H] < -1
disk stars halo stars
open clusters globular clusters

Which star population is very old and is metal poor?

II stars
They are relatively old stars, with ages ranging from 2 – 14 billion years. Extreme Population II stars (the most metal poor) are found in the halo and the globular clusters; these are the oldest stars.

Which is more metal poor the sun or a star?

The more negative this value, the more metal-poor the star is (or, at least, iron poor) than our own sun, which is considered of a fairly recent generation. Lower metallicities are typical of earlier generations of stars, and so may be described as “old”. Note, however, that they need not necessarily be old stars.

Which is the third population of metallicity stars?

Metallicity. These became commonly known as Population I (metal-rich) and Population II (metal-poor) stars. A third stellar population was introduced in 1978, known as Population III stars. These extremely metal-poor stars were theorised to have been the “first-born” stars created in the Universe.

What kind of stars have high mass of iron?

Iron, built up in massive stars and also later in Type Ia (white dwarf) supernovae: prompt and delayed release after stars are formed, involve high and low mass stars Alphas, built up in massive stars: prompt release, high mass stars

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