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randa177
- 91
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why is getting the age from CMD more accurate than getting it from photometry?
mgb_phys said:CMD isn't a very common abbreviation, most people would say HR diagram.
Do you mean - how to get the age of stars from a color magnitude (ie Hertzsprung–Russell) diagram?
mgb_phys said:Not sure I understand the question. You use photometry to get the color index of the star. Then plotted on the HR diagram gives you the age (or at least the evolutionary state of the star) for an accurate age you would also need to know metalicity and mass.
A CMD, or color-magnitude diagram, is a plot of the color and brightness of stars. It is used to determine the ages of stars by comparing the location of individual stars on the diagram to theoretical models of stellar evolution. Younger stars tend to be bluer and brighter, while older stars are redder and fainter.
The accuracy of age determinations using CMDs can be affected by a variety of factors. The precision of age measurements depends on the quality of the data, including the accuracy of the stellar distances and the completeness of the observed sample. Additionally, uncertainties in the physical properties of stars, such as their mass and composition, can also affect age estimates.
CMDs are most commonly used to determine the ages of main sequence stars, which are stars that are actively fusing hydrogen in their cores. However, they can also be used to estimate the ages of evolved stars, such as red giants and white dwarfs. These stars may have different evolutionary paths and therefore may have different locations on a CMD, but their ages can still be estimated using theoretical models.
New techniques and technologies, such as high-resolution spectroscopy and precise photometric measurements, can greatly improve the accuracy of age determinations using CMDs. These advancements allow for more accurate measurements of stellar properties and can also provide more complete samples of stars, leading to more precise age estimates.
While CMDs are a powerful tool for determining the ages of stars, they do have some limitations. For example, they are most effective for stars within our own Milky Way galaxy and may not be as accurate for stars in other galaxies. Additionally, some stars may be affected by factors such as binary companions or interactions with other stars, making it more difficult to accurately determine their ages using CMDs alone.