21May2013

New Stars Found In Southern Cross

This photo, taken in late February, shows the constellation of the Southern Cross (Crux), at the top center of the image, as viewed from Gramado Town in southern Brazil. Provided and copyright by: Fabiano Diniz, Federal University of Parana

New stars have been recently discovered in the Southern Cross, or Crux, by scientists in the United States. This discovery could affect the flags of many nations world-wide.

These would include New Zealand, Australia, Papua New Guinea, Samoa and Brazil, although the new star is located very close to the westernmost star and invisible to the naked eye. The American scientists found the new stars in the Southern Cross by using the Chandra X-ray Observatory, a space satellite run by NASA (National Aeronautics and Space Administration) which uses x-rays.

When the scientist team, led by David Cohen of Swarthmore College in Pennsylvania, were using the Chandra telescope, they, to their surprise, saw two x-ray glows, each representing stars, where they expected to see one. The new star appears to be orbiting Beta Crucis, the westernmost star in the Southern Cross, once every 2,000 years.

Doctor Nick Lomb, an astronomer at the Powerhouse Museum, Sydney, Australia, said that the reason the star had not been found before was because the glare from Beta Crucis is too great and “It would be like looking for a glow worm next to a floodlight.” Before the recent discovery, it was already known that Beta Crucis had a partner, which is invisible to the human-eye.

Mr Cohen said that they found it by accident, as they were really trying to get information about the x-rays emitted by Beta Crucis. “We were interested in how the highly supersonic stellar winds of hot, luminous stars produce X-rays.”

http://home.vicnet.net.au/~rasigsau/images/australian_flag.gif

Schematic layout of the Australian Flag featuring the Southern Cross.

The star found at the bottom of the Southern Cross, Alpha Crucis “Acrux”, also has a partner star, which is also invisible to the human-eye. This invisible partner is not featured on any flags. Dr Lomb said the apparent separation between each star is like looking at two headlights from 100 kilometres away, even though the two stars are actually 60 billion kilometres away from each other.

Dr Lomb said that if Australia was to put all eight stars in the Southern Cross onto the Australia flag then “the flag would have to be huge, probably the size of Sydney.” Astronomer Alan Gilmore from University of Canterbury’s Mount John observatory, also agreed that flags should not be altered because it is not about how many stars there are in the Southern Cross, but the magnitude of the stars. Mr Gilmore said: “What you see by eye is what you see on the flag. If you wanted to add more stars, there’s no end of stars you can put on if you go down in order of brightness. It would get very confusing.”

Mr Gilmore has said that in 20,000 years that Southern Cross will be different anyway, because the top star, Gamma Crucis is 90 light years away from Earth, while Alpha Crucis, Beta Crucis and Delta Crucis are all around 350 light years away and they are all moving in different directions. And Dr Lomb said that Alpha, Beta and Delta Crucis will die in a few million years.

These findings were presented to the American Astronomical Society, Seattle, Washington, by an undergraduate of Mr Cohen’s team, Michael Kuhn. Source: Amarachiakoro26

 

Indigenous Stories of the Southern Cross

 

Australian Aboriginal tribal Colours

There are a number of different Indigenous stories of Crux and the Pointers. To the people of the central desert, the Southern Cross is the footprint of the wedge-tailed eagle, and the two pointers are his throwing stick.

Stories from the Noongar people of Western Australia depict the stars of Crux as five naughty youngsters who scattered when a spear was thrown at them. Another Noongar story has the stars of Crux and the pointers as seven sacred men/spirits who came to Earth and made the laws, and started the 14 different language groups to re-establish the good marriage state.

Several stories of Crux emerge from different Indigenous groups in Victoria, with the Pointers (α and β Centauri) signifying brothers for many people including the Wotjobaluk, Kurnai, Ya-itma-thang and Kurnai. For the Wotjobaluk, these brothers are known as Bram Brambult.

They speared and killed Tchingal the Emu (whose head is the Coalsack), who was chasing Bunya the Possum – the star at the head of the cross (γ Crucis). In the Kulin’s stories the Pointers were two of the creator spirit Bunjil’s young men, Djurt-djurt and Thara. The Kulin also believed two stars of the Cross represented Yukope, the green parakeet, and Dantum, the Blue Mountain parrot. For both the Kurnai and the Ya-itma-thang, the Southern Cross was an emu.

Did you know?

Crux used to be visible in the Northern Hemisphere. In ancient Greece it formed the hind legs of the constellation Centaurus. But it hasn’t been seen in Athens for over a thousand years. The position of Crux in the sky hasn’t changed, but the Earth’s axis has!  Imagine the Earth spinning on its axis like a spinning top – as the top spins the axis rotates.

This rotation is called precession. The Earth’s axis precesses once every 26,000 years, which changes the area of the night sky we can see. In a few thousand years, precession will shift the South Celestial Pole, so Crux will no longer point south. Precession also means our seasons will shift through the calendar, so in 13,000 years our summer will be in June and we can finally have a white Christmas!