Tag: extragalactic astronomy

For the first time, our region of the universe has a map and a name ~ Video

washingtonpost.comScientists have redrawn the cosmic map of our corner of the universe, using new tools to define which galaxies interact with our own. The so-called supercluster of galaxies that contains the Milky Way has been named "Laniakea,"&nbs...

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‘We finally found it’: Scientists get first look at ‘monster’ galaxy’s formation




theweek.com

Yale astronomers have at last gotten a first look at the formation of "the universe's monster galaxies," Phys.org reports, and the results are fascinating.

The research, which used data from NASA's Hubble Space Telescope, NASA's Spitzer Space Telescope, ESA's Herschel Space Observatory, and the W.M. Keck Observatory in Hawaii, was published Wednesday in the journal Nature. It marks the first time astronomers have seen the earliest stages of a massive galaxy's formation.

The Keck II telescope's Near Infrared Spectograph allowed the astronomers to watch the galaxy — officially called GOODS-N-774 but nicknamed "Sparky" — produce massive amounts of stars. Witnessing this formation gave them new insight into how ancient galaxies may have formed 11 billion years ago — only 3 billion years after the Big Bang.

The scientists found that Sparky's formation is unique to the early universe that it developed in: its rapid gas movement was often violent, and it produced as many as 300 stars per year — an astounding amount of stars, especially considering its relatively tiny size (it measured roughly 6,000 light-years across). The Milky Way, by contrast, only produces roughly 10 stars annually, but spans 100,000 light-years.

"I think our discovery settles the question of whether this mode of building galaxies actually happened or not," said Pieter van Dokkum, one of the Yale astronomers. "The question now is, 'How often did this occur?' We suspect there are other galaxies like this that are even fainter in near-infrared wavelengths. We had been searching for this galaxy for years, and it's very exciting that we finally found it." --Meghan DeMaria

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Cosmic Grains Pre-date Our Entire Solar System

Stardust capsule
The cosmic particles were stored safely in a capsule that Stardust delivered to Earth in 2006
By Maria Dasi Espuig, Science Reporter
bbc.com


Scientists may have identified the first known dust particles from outside our Solar System, in samples returned to Earth by a Nasa space mission.
A team of scientists, with the help of more than 30,000 worldwide citizens, has identified seven exotic grains.
The material was captured by the Stardust spacecraft and brought back to Earth in 2006.
The region between stars - interstellar space - is not entirely empty, but is filled with microscopic particles.
The material that forms interstellar dust is a product of the aeons of stellar birth, evolution and death that went into building our cosmic neighbourhood. The material originated in the extremely hot interior of other stars before the Sun was born, and were expelled into interstellar space where they condensed into tiny rocks as they cooled down.
Having these particles on Earth means that scientists can characterise them in unprecedented detail. The composition and structure of the collected samples could help explain the origin and evolution of interstellar dust.

Scientists inspecting collector tray 
The collected samples could help explain the origin and evolution of interstellar dust

Dr. Westphal, from the Space Sciences Laboratory at the University of California, Berkeley, told BBC News: "Our results are giving us the first glimpse of the complexity and diversity of interstellar dust particles."
A preliminary analysis by Dr. Wesphal and colleagues, published in Science, showed that the seven interstellar candidates are much more diverse in size, chemical composition and structure than anyone had pictured before based on previous astronomical observations and theories.
"It could easily have been that our answer when we did this project was to find that all interstellar dust particles are similar, and we are not finding that at all. They are all different from each other."
Comet dust, in contrast, is younger. The material out of which our Solar System formed was heated, melted, mixed and transformed as the Sun and the planets began to take shape. The comets represent the relics of this process and are therefore representative of the composition of our early planetary system.
Stardust was two missions in one. Although it is mostly known for its close encounter with Comet Wild 2, the spacecraft also captured dust flowing in the interstellar dust stream. This stream carries ancient particles older than our Sun, from different parts of our galaxy.

Stardust artist impressionStardust captured dust particles using a retractable grid of aerogel
Captured dust Stardust was equipped with a device called the Interstellar Dust Collector, a tennis-racket sized mosaic of 132 tiles made of the lightest manmade solid, referred to as aerogel. This is a silicon-based material that is more than 99% empty space.
The dust particles can travel at hypervelocity, more than 5km per second. Like a net, this light, fluffy aerogel captured dust particles without vaporising them by slowing them down gradually.
More than 30,000 volunteers who signed up to the Stardust@home project examined millions of images of the aerogel in search of the carrot-shaped trails left by the incoming hypervelocity particles, which are about two millionths of a metre in diameter.
But not all of the particles embedded in the aerogel are of interstellar origin. The researchers determined that all but three of the tracks were caused by tiny bits of the spacecraft.
Four more possible interstellar particles, as tiny as 0.4 millionths of a metre, were found encrusted in minute craters in the aluminium foil around the aerogel tiles.
The seven dust particles are composed of different silicates - minerals consisting of silica, oxygen and metals - which indicate that each particle may have its own history.
"[The particles] may have formed in one star and were then processed over tens of millions of years in the interstellar medium and mixed in with particles coming from other stars or even particles that formed in the interstellar medium in cold molecular clouds, so it's probably a mixture of lots of different things," explained Dr. Westphal.

Particle track in aerogelThe dust particles leave a cone-shaped trail as they are slowly decelerated by the aerogel
Ongoing work Dr. Westphal and his colleagues plan further tests to the results.
The final proof lies in the levels of different chemical oxygen forms, known as isotopes, within them. A different concentration than that found in our Solar System would indicate their extra-solar origin.
It will require several years of hard work to refine the techniques available to measure the abundance of oxygen isotopes in the dust particles without destroying them.
Dr. Westphal added: "It's a necessary step before we dare to do anything with the real thing. The problem is that they are just so rare… we cannot dare to take any chances."
More data remain to be analysed. Half of the aerogel tiles and an even larger fraction of the foils will be scrutinised in the next two to three years.
In the meantime, Dr. Westphal said the team members are "having fun".

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