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Peering into the Milky Way's Past --Our Sun was a Late Bloomer (Weekend Feature)

 

 

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In one of the most comprehensive multi-observatory galaxy surveys yet, astronomers find that galaxies like our Milky Way underwent a stellar "baby boom," churning out stars at a prodigious rate, about 30 times faster than today. Our sun, however, is a late "boomer." The Milky Way's star-birthing frenzy peaked 10 billion years ago, but our sun was late for the party, not forming until roughly 5 billion years ago. By that time the star formation rate in our galaxy had plunged to a trickle.

Missing the party, however, may not have been so bad. The sun's late appearance may actually have fostered the growth of our solar system's planets. Elements heavier than hydrogen and helium were more abundant later in the star-forming boom as more massive stars ended their lives early and enriched the galaxy with material that served as the building blocks of planets and even life on Earth.

The image above is an artist's view of night sky from a hypothetical planet within a young Milky Way-like galaxy 10 billion years ago, the sky are ablaze with star birth. Pink clouds of gas harbor newborn stars, and bluish-white, young star clusters litter the landscape.

Astronomers don't have baby pictures of our Milky Way's formative years to trace the history of stellar growth so they studied galaxies similar in mass to our Milky Way, found in deep surveys of the universe. The farther into the universe astronomers look, the further back in time they are seeing, because starlight from long ago is just arriving at Earth now. From those surveys, stretching back in time more than 10 billion years, researchers assembled an album of images containing nearly 2,000 snapshots of Milky Way-like galaxies.

The new census provides the most complete picture yet of how galaxies like the Milky Way grew over the past 10 billion years into today's majestic spiral galaxies. The multi-wavelength study spans ultraviolet to far-infrared light, combining observations from NASA's Hubble and Spitzer space telescopes, the European Space Agency's Herschel Space Observatory, and ground-based telescopes, including the Magellan Baade Telescope at the Las Campanas Observatory in Chile.

"This study allows us to see what the Milky Way may have looked like in the past," said Casey Papovich of Texas A&M University in College Station, lead author on the paper that describes the study's results. "It shows that these galaxies underwent a big change in the mass of its stars over the past 10 billion years, bulking up by a factor of 10, which confirms theories about their growth. And most of that stellar-mass growth happened within the first 5 billion years of their birth."

The new analysis reinforces earlier research which showed that Milky Way-like galaxies began as small clumps of stars. The galaxies swallowed large amounts of gas that ignited a firestorm of star birth.

The study reveals a strong correlation between the galaxies' star formation and growth in stellar mass. So, when the galaxies slow down making stars, their growth decreases as well. "I think the evidence suggests that we can account for the majority of the buildup of a Milky Way-like galaxy through its star formation," Papovich said. "When we calculate the star-formation rate of a Milky Way-like galaxy in the past and add up all the stars it would have produced, it is pretty consistent with the mass growth we expected. To me, that means we're able to understand the growth of the 'average' galaxy with the mass of a Milky Way galaxy."

The astronomers selected the Milky Way-like progenitors by sifting through more than 24,000 galaxies in the entire catalogs of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), taken with Hubble, and the FourStar Galaxy Evolution Survey (ZFOURGE), made with the Magellan telescope.

They used the ZFOURGE, CANDELS, and Spitzer near-infrared data to study the galaxy stellar masses. The Hubble images from the CANDELS survey also provided structural information about galaxy sizes and how they evolved. Far-infrared light observations from Spitzer and Herschel helped the astronomers trace the star-formation rate.

The Daily Galaxy via Hubblesite.com

Comments

This is how God decided when and where to place the solar system and our earth. He decided just like Genesis says. Think about the story of creation and then tell me that this is not the way it happened. The people who wrote His Word had no scientific knowledge as we do today. It did not matter. He told us the story about His creation and we simple humans wrote it with the words we had at the time. God the Father has all the time in eternity and so He placed us so far away from anything else so we are safe and secure. After all we are His Creation. He is not ours. We can come up with all kinds of theories and they are just that - theories. Prove them and they are fact. Where is the proof other than creation because of its exactness and precise design? Take it off course just once and it does not get back on course. You know that for a fact.

This is how God decided when and where to place the solar system and our earth. He decided just like Genesis says. Think about the story of creation and then tell me that this is not the way it happened. The people who wrote His Word had no scientific knowledge as we do today. It did not matter. He told us the story about His creation and we simple humans wrote it with the words we had at the time. God the Father has all the time in eternity and so He placed us so far away from anything else so we are safe and secure. After all we are His Creation. He is not ours. We can come up with all kinds of theories and they are just that - theories. Prove them and they are fact. Where is the proof other than creation because of its exactness and precise design? Take it off course just once and it does not get back on course. You know that for a fact.

Ouch Dough. There is no God, Allah, Manitou... what ever. WE... we only are in charge (and responsible) for our lives and actions and no one, not a politician, a priest and no not-existing gaseous being tells me what to do!
If people don't understand how the universe works is a matter of education and no excuse to "blame" a not existing "higher being" for its existence.
Religion is just a "fine way" to control people ;-).. ask the Vatican.

Non existing gaseous being. Good one. Yet people put all their faith in their "new" religion science, which also was by the way stolen from Africa

The only reason "science" was invented anywhere is because it was developed by humans stopping to look at the world around them. At the time this early human looked at the wonder of his world, and called it "Science", all of his kind were living in the birthplace of humanity. There were no countries, no continents, no religions and hence there is no right right to claim superiority for any "state".

Oh, one last thing. Scientific investigation cant prove anything about God.

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