Earliest galaxy spotted by astronomers

Astronomers have found the most distant galaxy yet, shown in this artist's rendering, a finding that pushes back scientists' view of the universe to about 700 million years after its creation. (Reuters)

Astronomers have found the most distant galaxy yet, a discovery that pushes back scientists' view of the universe to about 700 million years after it is thought to have come into existence.

The universe is thought to be about 13.8 billion years old.

Light from the galaxy, designated by scientists as z8_GND_5296, took about 13.1 billion years to reach the orbiting Hubble Space Telescope and the Keck Observatory in Hawaii, both of which detected the galaxy in infrared light.

"We are learning so much about a region so far back in time it's hard to comprehend. This galaxy we're seeing is almost 13.1 billion years ago and so this was something like 8 billion years before our sun was even born and of course much longer after that until life came around," said lead researcher Steven Finkelstein, an assistant professor with the University of Texas at Austin.

Surprisingly, out of a pool of 43 candidate distant galaxies, z8_GND_5296 was the only one that revealed the key chemical evidence needed to confirm its distance.

Although some more-distant candidate galaxies have been detected, they have not yet been confirmed in this way.

The discovery left Finkelstein and colleagues wondering if they had uncovered a clue to a bigger mystery: How soon did light from the universe's first stars and galaxies pierce an obscuring veil of hydrogen gas that existed early in its history?

Scientists believe that at some point, high-energy ultraviolet radiation from exploded stars split the intergalactic hydrogen atoms into electrons and protons. Once ionized, the hydrogen would be electrically conductive and no longer scatter light.

That may have happened about the time of z8_GND_5296's existence.

The galaxy, which is about a billion times as massive as the sun, has two unusual characteristics, which may be a factor in why it is visible, while potential sister galaxies are not.

First, z8_GND_5296 is forming stars at a very fast pace, pumping out about 100 times more stars than the Milky Way galaxy, so it may be brighter than the other candidate galaxies.

Second, it contains a surprisingly high percentage of elements heavier than hydrogen and helium.

Those elements are forged by nuclear fusion inside stars, so either the galaxy contains the exploded remains of lots of massive stars or it formed in a region of space that had been previously seeded with the remnants of a prior generation of stars, scientists said.

"It could be that this one galaxy lives in an over-dense region of (ionized hydrogen) so we can see it ... but that's a little bit of conjecture. For all we know these other galaxies have just a lot more hydrogen gas within the galaxies themselves and that's why we can't see them," Finkelstein said.

He and colleagues hope to conduct a wider survey for ancient galaxies with Hubble, but more details about z8_GND_5296 will likely have to wait until NASA launches its successor observatory, the James Webb Space Telescope, targeted for launch in 2018.

The research appears this week in the journal Nature.

View the original article here

Researchers alarmed by 'puzzling' changes in resident orcas

A Vancouver Aquarium whale researcher is sounding the alarm over what he calls "puzzling" changes observed in the resident killer whale pods that live off the northern coast of B.C. and Alaska.

Dr. Lance Barrett-Lennard, a senior marine mammal scientist with the aquarium, says he fears changes in the ocean environment are prompting odd behaviour and an unusually high mortality rate, after spending the summer observing the whales aboard a research vessel.

Barrett-Lennard says one resident pod has lost seven matriarchs over the past two years, an unusually high death rate, and he's also noticed a lack of vocalizations from the normally chatty mammals.

“Resident killer whales are typically very vocal in the summer but, for the second year in a row, they have been remarkably quiet,” said Barrett-Lennard.

“So quiet that we often had difficulty finding them.”

The lack of vocalizations was just one of three unusual changes observed by the cetacean research team. Resident orcas were also seen the past two summers travelling in small groups, farther offshore to find food — behaviour more typical in winter than summer.

At the same time, the Barrett-Lennard says the number of normally transient killer whales, also known as the Bigg's whale, has been increasing over the past 25 years. In the 1990's, resident orcas were sighted much more frequently than Bigg's orcas, but now the number of sightings is nearly equal.

“It’s unclear at this point if the loss of so many matriarchs or the increase in Bigg’s killer whales is having an impact on resident killer whale behaviour, but the changes we’ve seen over the last two years are striking and beg an explanation," says  Barrett-Lennard.

The difference two years makes

The Vancouver Aquarium provided two audio recordings made near resident killer whales off B.C.'s Central Coast.

The first, from 2011, is full of many calls as well as echolocation sounds and is typical of the sounds of resident killer whales prior to 2012.

The second, from 2013, is much quieter and consists mainly of the echolocation 'ticks' that the whales use to find fish. "Communication calls are absent apart from a quiet call at the 15-second mark," the Aquarium says.

View the original article here