In astronomy, usually “the more we know, the more we know that we don’t know”

The galaxy 1-Zwicky18 is very similar in composition to galaxies which formed in the first billion years after the big bang (Source: NASA/Hubble)
The galaxy 1-Zwicky18 is very similar in composition to galaxies which formed in the first billion years after the big bang (Source: NASA/Hubble)

Main Points:

Astronomers have found that stars in the very beginning of universe used very little dust. This finding has enhanced the mysteriousness of the formation of very early stars.

Published in:

Nature

Study Further:

Very little dust in the early universe:

Our present knowledge shows that a huge amount of dust and gas is required to make stars and galaxies but this recent study has opposed our present knowledge. This study is presenting very little dust in the early universe. It shows that very little dust was used to make very early stars of the universe meaning presently known models may not be applied to the early stars and galaxies.

In the present study, astronomers studied the dust on analogue galaxy called 1-Zwicky18, located 58 million light years away, with the help of European Space Agency’s Herschel space telescope. This galaxy is found to have similar physical conditions existing in the first galaxies.

“The local dwarf galaxy I Zwicky 18, which has a metallicity about 4 per cent that of the Sun’sand is forming stars less rapidly (assembly time about 1.6 × 109years) than Himiko ( a galaxy formed about 840 million years after the Big Bang) but still vigorously for its mass, is also very dust deficient and is perhaps one of the best analogues of primitive galaxies accessible to detailed study,” Researchers wrote.

“We measured the lowest dust mass that had ever been measured, and much lower than what we were expecting to get by a factor of about 100,” said Dr David Fisher of the University of Maryland and Swinburne University.

“It’s a big mystery,” he says. “This problem of how to make stars in the early universe may be even greater than we thought it was.”

Here, I am quoting Sir Humphry Davy, “The more we know, the more we feel our ignorance; the more we feel how much remains unknown.”

Another issue posed by the lack of dust:

Lack of dust is also presenting problems in study of early galaxies with the help of present technology of telescopes.

“It’s saying these galaxies are going to be much fainter than we were expecting,” said Fisher.

“We probably won’t be able to detect them very well, even with ALMA (the Atacama Large Millimetre submillimetre Array in Chile), which is the most powerful telescope on Earth right now.

“People have been using ALMA to try to observe dust in early universe galaxies, and they’re failing to find detections in all but the most extreme super bright galaxies, because there’s much less dust than the theories are telling us.”

Sources:

Mystery of the first stars deepens – ABC Science (http://goo.gl/UnF35E)

David B. Fisher et al. (2013). The rarity of dust in metal-poor galaxies Nature DOI: 10.1038/nature12765

Usman Zafar Paracha

Usman Zafar Paracha is Assistant Professor, Pharmaceutics, in Hajvery University, Lahore, Pakistan.