The cosmic case of the missing stars

A MASSIVE population of stars is missing, and scientists are stumped as to where it could be.

New observations from the Hubble Space Telescope challenge a previous theory for the apparent disappearance of a massive number of stars.

Because some star clusters around our Milky Way galaxy have fewer stars than observations suggest they should, astronomers suspected many of these stars were ejected from their clusters to ultimately find new homes in the Milky Way.

But the new Hubble telescope views of the distant Fornax galaxy cluster challenge this picture. That’s because, in the case of Fornax, such ejected stars would have nowhere to hide.

“If these kicked-out stars were there, we would see them — but we don’t!” Frank Grundahl of Aarhus University in Denmark, a co-author on the paper, said. The finding draws into question whether the missing stars were ever present at all, in globular clusters around Fornax or the Milky Way.

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CrazyNeutrino said:

The cosmic case of the missing stars

A MASSIVE population of stars is missing, and scientists are stumped as to where it could be.

New observations from the Hubble Space Telescope challenge a previous theory for the apparent disappearance of a massive number of stars.

Because some star clusters around our Milky Way galaxy have fewer stars than observations suggest they should, astronomers suspected many of these stars were ejected from their clusters to ultimately find new homes in the Milky Way.

But the new Hubble telescope views of the distant Fornax galaxy cluster challenge this picture. That’s because, in the case of Fornax, such ejected stars would have nowhere to hide.

“If these kicked-out stars were there, we would see them — but we don’t!” Frank Grundahl of Aarhus University in Denmark, a co-author on the paper, said. The finding draws into question whether the missing stars were ever present at all, in globular clusters around Fornax or the Milky Way.

more….

scroll down to see comparative pics

> Because some star clusters around our Milky Way galaxy have fewer stars than observations suggest they should …

That’s on the basis of an assumed ratio of dark matter to ordinary (baryonic) matter. Many small galaxies near the Milky Way have lots of dark matter but very low luminosity. Hence the statement “astronomers suspected many of these stars were ejected”.

I take it that what has really been found is a dark matter excess in the Fornax Cluster. That should not be too surprising, as many clusters have an excess of dark matter. There’s no real reason for the Fornax Cluster to be any different. The different situation is expected to be the Milky Way, because it sits in a thin filament of gas, dust, stars and dark matter that connects the Fornax Cluster to the Virgo Cluster. The thin filament would not be expected to have a representative ratio of dark matter to ordinary matter.

Oops, is this the same topic as earlier thread “Mystery of Globular Star Clusters’ Formation Deepens” CrazyNeutrino?