What does metal-poor mean?
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.
Where in our galaxy will we find the most metal-rich stars?
the Milky Way galaxy
Population I, or metal-rich, stars are young stars with the highest metallicity out of all three populations, and are more commonly found in the spiral arms of the Milky Way galaxy.
What is metal in astronomy?
Astronomers refer to all the chemical elements heavier than hydrogen and helium as ‘metals’, even though this includes elements such as carbon and oxygen which are not considered metals in the normal sense. The production of metals is a consequence of stellar evolution. …
Why is the sun metal-rich?
Like any star in its prime, the sun consists mainly of hydrogen atoms fusing two by two into helium, unleashing immense energy in the process. But it’s the sun’s tiny concentration of heavier elements, which astronomers call metals, that controls its fate.
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.
Which star types are considered metal poor?
The rationale for analyzing metal-poor stars is that they are long-lived, low-mass objects, the majority of which are main sequence and giant stars that have preserved in their atmospheres the chemical signatures of the gas from which they formed.
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.
Which metal is more in universe?
Iron
Iron is the most abundant metal in the Universe.
Are there any first-generation stars left?
Astronomers using the NASA/ESA Hubble Space Telescope have found no evidence of hypothetical first-generation stars — called Population III stars — as far back as when the Universe was just 500 million years old. An artist’s impression of the early Universe.
Why can the metallicity of a star tell you something about its age?
The metallicity of an astronomical object may provide an indication of its age. When the universe first formed, according to the Big Bang theory, it consisted almost entirely of hydrogen which, through primordial nucleosynthesis, created a sizeable proportion of helium and only trace amounts of lithium.
Which star population is very old and is metal poor?
Extreme Population 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.
Are there any first generation stars left?
What kind of structures are found in radio galaxies?
Radio galaxies, and to a lesser extent, radio-loud quasars display a wide range of structures in radio maps. The most common large-scale structures are called lobes: these are double, often fairly symmetrical, roughly ellipsoidal structures placed on either side of the active nucleus.
How big is the largest radio galaxy in the universe?
The largest radio galaxies have lobes or plumes extending to megaparsec scales (more in the case of giant radio galaxies like 3C236 ), implying a timescale for growth of the order of tens to hundreds of millions of years.
Why do we use the word metallicity in astronomy?
Metallicity. In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium. Most of the physical matter in the Universe is in the form of hydrogen and helium, so astronomers use the word “metals” as a convenient short term for “all elements except hydrogen…
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.