© ESO/H.H. HeyerThe Milky Way arcs into a panorama in the southern sky, taken from the Paranal Observatory, Chile.
When our galaxy was born, around 13 billion years ago, a plethora of clusters containing millions of stars emerged. But over time, they have been disappearing. However, hidden behind younger stars that were formed later, some old and dying star clusters remain, such as the so-called E 3. European astronomers have now studied this testimony to the beginnings of our galaxy.Globular clusters are spherical-shaped or globular stellar groupings -- hence its name- which can contain millions of stars. There are about 200 of them in the Milky Way, but few are as intriguing to astronomers as the E 3 cluster.
It is situated around 30,000 light years away, in the southern constellation of Chameleon. A team of Spanish and Italian astronomers have named it "a ghost from the Milky Way's past" in an article published recently in the
Astronomy & Astrophysics journal.
"This globular cluster, and a few similar ones -- such as Palomar 5 or Palomar 14 -- are 'ghosts' because they appear to be in the last stages of their existence, and we say 'from the past' because they are very old. They were formed when our galaxy was virtually new-born, 13 billion years ago," says one of the authors, Carlos de la Fuente Marcos.
E 3 is hidden behind younger and brighter objects located between the cluster and Earth, but it has been possible to analyse it thanks to the Very Large Telescope (VLT) held in the European Southern Observatory (ESO) in Cerro Paranal, Chile. The data obtained revealed some surprises.
"Unlike typical globular clusters, which contain hundreds of thousands and in some cases millions of stars, the object studied only has a few tens of thousands of them," says De la Fuente Marcos. "Additionally, it doesn't have the typical circular symmetry, but a much distorted, almost ghostly, rhomboidal shape, contorted by the galactic gravitational waves."
According to another study on E 3 by Michigan State University (USA) researchers, published in The Astrophysical Journal, this cluster is chemically homogeneous, that is, it doesn't have several star populations in its interior.
"This is characteristic of an object that was created in block, in one single episode, like what is supposed to have happened when our galaxy was born: very large star clusters (containing millions of stars) were formed, but what remains of them today are objects like E 3, ghosts from a distant past," says De la Fuente Marcos. He explains that the study of these objects "enables us to gain insight into the infancy of the Milky Way."
Native or captured?Despite the recently published new data on this strange globular cluster, astronomers still have to clarify if it was really formed in our galaxy or not. It is known that some of its clusters are not native to the Milky Way, but were captured, even though they can currently be seen in its interior. Long ago, our galaxy cannibalised other smaller galaxies and kept their globular clusters. The rest were formed
in-situ.
In the article, it is suggested that the object analyzed could be dynamically related to other clusters, such as 47 Tucanae, one of the richest and largest of the Milky Way. They could even share the same stream of stars. If this were the case, it would support the hypothesis that E 3 was captured in the distant past.
"We hope to obtain new data in 2016, thanks to more spectroscopic observations, and perhaps we will be able to give answers to these questions," says De la Fuente Marcos, an independent astronomer who collaborates with colleagues from the Northern Catholic University and ESO in Chile, and the University of Padua, Italy.
Journal Reference:R. de la Fuente Marcos, C. de la Fuente Marcos, C. Moni Bidin, S. Ortolani, G. Carraro. "Ghosts of Milky Way's past: the globular cluster ESOโ37-1 (Eโ3)."
Astronomy & Astrophysics, 2015; 581: A13
DOI.
Source: Plataforma SINC
It's something of a mystery that globular clusters contain stars that are close to the alleged age of the universe. The argument goes that these are remnants of dwarf galaxies (like the Greater and Lesser Magellenic Clouds) that have now been absorbed by the Milky Way. Maybe so.
But I have a few doubts about 'conventional science'. Which is regularly been proven wrong. I especially have doubts about modern cosmology.
The conventional view is that the universe is expanding, leading to a unexplained concept of 'dark energy'. I wonder if the speed of light is actually a constant.
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Also the 'tired light' concept.
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Can anyone show me a proof that the speed of light on a galaxy billions of alleged light-years away is the same we see locally? If the speed of light slows over time, or distance, wouldn't this explain this so-called dark energy expansion?
There is also the concept of 'dark matter' that I can't help but doubt as well.
The original argument for dark matter was the 'flat galactic rotation curve', which essentially means that stars were observed to rotate around our galactic core somewhat faster that they should, assuming the concentration of mass of our galaxy is concentrated in the core. Therefore there must be some 'unknown and undetectable matter that affect the measurements. And hence dark matter.
But there have been a few recent observations that I claim puts that theory into doubt. For one, there is the WISE project that found there were ten times the number of red dwarf stars that were expected. So how many brown dwarf stars out there? Also, there has been found that the Milky way is surrounded by a vast halo of hot gas, pushing a large amount of the mass of our galaxy much further out. Also found around around our nearest significant galactic neighbour.
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Perhaps this also explains 'dark matter' bending of light around galaxies much further away. Is this just bending of light via (as yet) unobserved galactic halos? We all (or should) understand how the speed of light slows down passing through water, hence refraction (Snell's Law, or phase velocity, leading to Cherenkov radiation).
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Being a devil's advocate here. I'd like to hear from someone that can sensibly prove otherwise.