The Long-Lost Siblings of the Sun
The sun was born in a family of stars. What became of them?
Key Concepts
* The sun is a solitary star, and astronomers have traditionally assumed it formed as such. Yet most stars are born in clusters, and scraps of evidence from meteorites and from the arrangement of comets suggest that our sun was no exception.
* Its birth cluster could have contained 1,500 to 3,500 stars within a diameter of 10 light-years—a big, unhappy family whose larger members bullied the small fry and which broke up not long after our solar system came into being.
* Although the sun’s siblings have long since dispersed across the galaxy, observatories such as the European GAIA satellite will be able to look for them. Their properties might fill in the gaps of the solar system’s deep history.
People have often sought solitude in the starry night sky, and it is an appropriate place for that. The night is dark because, in cosmic terms, our sun and its family of planets are very lonely. Neighboring stars are so far away that they look like mere specks of light, and more distant stars blur together into a feeble glow. Our fastest space probes will take tens of thousands of years to cross the distance to the nearest star. Space isolates us like an ocean around a tiny island.
Yet not all stars are so secluded. About one in 10 belongs to a cluster, a swarm of hundreds to tens of thousands of stars with a diameter of a few light-years. In fact, most stars are born in such groups, which generally disperse over billions of years, their stars blending in with the rest of the galaxy. What about our sun? Might it, too, have come into existence in a star cluster? If so, our location in the galaxy was not always so desolate. It only became so as the cluster dispersed in due time.
A growing body of evidence suggests just that. Although conventional wisdom once held that the sun was an only child, many astronomers now think it was one of 1,000 or so siblings all born at nearly the same time. Had we been around at the dawn of the solar system, space would not have seemed nearly so empty. The night sky would have been filled with bright stars, several at least as bright as the full moon. Some would have been visible even by day. Looking up would have hurt our eyes.
The cluster into which the sun was probably born is now long gone. I have pieced together the available data and made an educated guess as to what it might have looked like. From these inferred properties, I have calculated the possible trajectories of former cluster members through the galaxy to figure out where they might have ended up. Although they have scattered and mixed in with millions of unrelated stars, they should be identifiable with the European Space Agency’s Global Astrometric Interferometer for Astrophysics (GAIA) satellite, scheduled for launch in 2011. Their orbits and sunlike compositions should give them away. Reuniting with our long-lost stellar siblings should enable astronomers to reconstruct the conditions under which a shapeless cloud of gas and dust gave rise to our solar system.
Memories of Our Birth
The most compelling evidence that the sun has close siblings emerged in 2003, when Shogo Tachibana, now at the University of Tokyo, and Gary R. Huss, now at the University of Hawaii at Manoa, analyzed two primitive meteorites that are thought to be almost pristine leftovers of solar system formation. They detected nickel 60, the product of the radioactive decay of iron 60, in chemical compounds where, by rights, iron should be found. It seems a game of chemical bait and switch took place in the meteorite: the compounds originally formed from iron, the iron metamorphosed into nickel, and the nickel was locked in place, forever an interloper.
The iron 60 had to be synthesized, injected into the solar system and incorporated into meteorites within its radioactive half-life, which, according to a new estimate published this past August, is 2.6 million years. That is a cosmic eyeblink. Therefore, the iron had to come from very nearby—and the likeliest source is a supernova explosion. Based on this and other isotopic measurements, Leslie Looney of the University of Illinois and his co-workers argued in 2006 that a supernova went off within a distance of five light-years when the sun was scarcely 1.8 million years old. The supernova might have been as close as 0.07 light-year. (The new half-life estimate will change these values, but not substantially.)
If the sun had been as secluded as it is today, the location and timing of the supernova would be quite a coincidence. Was a massive star simply passing by when it decided to blow up? No other supernova has ever gone off at such close range; if it had, it would probably have wiped out life on Earth. A much more plausible explanation is that the newborn sun and the exploding star were fellow members of a cluster. With stars packed so tightly together, a close supernova would not have been so improbable.
Original published at : http://www.scientificamerican.com/article.cfm?id=the-long-lost-sibl...
Key Concepts
* The sun is a solitary star, and astronomers have traditionally assumed it formed as such. Yet most stars are born in clusters, and scraps of evidence from meteorites and from the arrangement of comets suggest that our sun was no exception.
* Its birth cluster could have contained 1,500 to 3,500 stars within a diameter of 10 light-years—a big, unhappy family whose larger members bullied the small fry and which broke up not long after our solar system came into being.
* Although the sun’s siblings have long since dispersed across the galaxy, observatories such as the European GAIA satellite will be able to look for them. Their properties might fill in the gaps of the solar system’s deep history.
People have often sought solitude in the starry night sky, and it is an appropriate place for that. The night is dark because, in cosmic terms, our sun and its family of planets are very lonely. Neighboring stars are so far away that they look like mere specks of light, and more distant stars blur together into a feeble glow. Our fastest space probes will take tens of thousands of years to cross the distance to the nearest star. Space isolates us like an ocean around a tiny island.
Yet not all stars are so secluded. About one in 10 belongs to a cluster, a swarm of hundreds to tens of thousands of stars with a diameter of a few light-years. In fact, most stars are born in such groups, which generally disperse over billions of years, their stars blending in with the rest of the galaxy. What about our sun? Might it, too, have come into existence in a star cluster? If so, our location in the galaxy was not always so desolate. It only became so as the cluster dispersed in due time.
A growing body of evidence suggests just that. Although conventional wisdom once held that the sun was an only child, many astronomers now think it was one of 1,000 or so siblings all born at nearly the same time. Had we been around at the dawn of the solar system, space would not have seemed nearly so empty. The night sky would have been filled with bright stars, several at least as bright as the full moon. Some would have been visible even by day. Looking up would have hurt our eyes.
The cluster into which the sun was probably born is now long gone. I have pieced together the available data and made an educated guess as to what it might have looked like. From these inferred properties, I have calculated the possible trajectories of former cluster members through the galaxy to figure out where they might have ended up. Although they have scattered and mixed in with millions of unrelated stars, they should be identifiable with the European Space Agency’s Global Astrometric Interferometer for Astrophysics (GAIA) satellite, scheduled for launch in 2011. Their orbits and sunlike compositions should give them away. Reuniting with our long-lost stellar siblings should enable astronomers to reconstruct the conditions under which a shapeless cloud of gas and dust gave rise to our solar system.
Memories of Our Birth
The most compelling evidence that the sun has close siblings emerged in 2003, when Shogo Tachibana, now at the University of Tokyo, and Gary R. Huss, now at the University of Hawaii at Manoa, analyzed two primitive meteorites that are thought to be almost pristine leftovers of solar system formation. They detected nickel 60, the product of the radioactive decay of iron 60, in chemical compounds where, by rights, iron should be found. It seems a game of chemical bait and switch took place in the meteorite: the compounds originally formed from iron, the iron metamorphosed into nickel, and the nickel was locked in place, forever an interloper.
The iron 60 had to be synthesized, injected into the solar system and incorporated into meteorites within its radioactive half-life, which, according to a new estimate published this past August, is 2.6 million years. That is a cosmic eyeblink. Therefore, the iron had to come from very nearby—and the likeliest source is a supernova explosion. Based on this and other isotopic measurements, Leslie Looney of the University of Illinois and his co-workers argued in 2006 that a supernova went off within a distance of five light-years when the sun was scarcely 1.8 million years old. The supernova might have been as close as 0.07 light-year. (The new half-life estimate will change these values, but not substantially.)
If the sun had been as secluded as it is today, the location and timing of the supernova would be quite a coincidence. Was a massive star simply passing by when it decided to blow up? No other supernova has ever gone off at such close range; if it had, it would probably have wiped out life on Earth. A much more plausible explanation is that the newborn sun and the exploding star were fellow members of a cluster. With stars packed so tightly together, a close supernova would not have been so improbable.
Original published at : http://www.scientificamerican.com/article.cfm?id=the-long-lost-sibl...
Replies to This Discussion
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Permalink Reply by starseed on
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Actually,
if you are talking about a chemical bait and switch, then could this meteorite matter, not have come through a black hole? In some theories, that is where some star clusters or new stars came from. As a way of recycling old energy and matter into new stars? Perhaps the friction caused by otherwise low to almost non vibrating material passed through a wormhole would cause enough friction to recharge this matter into new star clusters.
If we are talking a bait and switch to chemical properties then the recharging process could be what function blackholes serve, as polarities of material are changed then it would also account for a bait and switch of properties.
Love and Light,
Starseed
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Permalink Reply by Elisabetta Errani Emaldi on -
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