Half of All Stars in Galactic Halos: Potential to Rethink Mass Estimates?

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In summary, the article discusses a recent study which claims that half of all stars are rogue stars, located in a faint halo around galaxies. This finding, if validated, would require researchers to reevaluate models of galactic formation and could potentially impact estimates of galactic mass. The study is available for reading on the arXiv website. The potential implications of this finding include a need to rethink the role of these rogue stars in the process of reionization and their impact on halo size, which could have implications for the distribution of mass within galaxies. The study's reliance on the LCDM model suggests that the existence of dark matter is still necessary for our current understanding of galactic formation.
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jim mcnamara
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I cannot get to the original Science publication to cite it. Science Now has a précis:
http://www.latimes.com/science/scie...ight-background-ebl-ciber-20141106-story.html

So the information below is not firsthand.

The claim is that one half of all stars are rogue stars, which are stars which well out into a very large, faint halo around galaxies. The article mentions that previously about 5% of all stars were thought to fall into this category.

It goes on saying that this finding, if validated, would cause researchers to revisit models of galactic formation.
Question: why would that cause reevaluation - a lot more previously unaccounted for mass? Does this finding have the potential to invalidate existing estimates of galactic mass?

Thanks for any comments.
 
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Thanks for that.
 
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jim mcnamara said:
Question: why would that cause reevaluation

From the article it looked more like a reevalution of how the light from these stars would inform on reionization (perhaps makes it even more difficult to understand) and halo size. The latter would have implications for masses and their distribution, I would think. I just scanned the provided paper, and it seems their models are based on LCDM, so presumably no problem there.
 
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Dark matter is the short answer. Without it, nothing makes a whole lot of sense.
 

What is the main finding of the study?

The main finding of the study is that half of all stars in galactic halos may have been formed from the accretion and disruption of smaller dwarf galaxies, rather than being part of the original galaxy's formation. This finding challenges previous mass estimates of galaxies and has implications for our understanding of galaxy evolution.

How was the study conducted?

The study used computer simulations to model the formation of galaxies and the accretion of smaller dwarf galaxies. The researchers also analyzed data from the Gaia space telescope to identify and track the movement of stars in the halo of the Milky Way galaxy. By comparing the results of the simulations to the real data, the researchers were able to estimate the contribution of accreted stars to the total mass of the Milky Way halo.

What are the implications of this study?

This study has important implications for our understanding of galaxy formation and evolution. It suggests that the contribution of accreted stars to the mass of galactic halos may have been underestimated in previous studies, potentially leading to an overestimation of the total mass of galaxies. This could have implications for other areas of astrophysics, such as dark matter research.

What are some potential future research directions based on this study?

Based on the findings of this study, future research could focus on further investigating the role of accreted stars in galaxy formation and evolution. This could involve more detailed simulations and observations of galactic halos to better understand the dynamics of accretion and disruption processes. Additionally, this study could inspire new research on the relationship between dark matter and accreted stars in galaxies.

Why is it important to reconsider mass estimates of galaxies?

Accurate mass estimates of galaxies are crucial for understanding the dynamics of the universe and the formation of structures within it. If our current estimates are biased due to underestimating the contribution of accreted stars, this could have significant impacts on our overall understanding of the universe. Reconsidering mass estimates can also lead to new insights and theories about the formation and evolution of galaxies.

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