In which nebula was our sun formed?

[mcs]

Is this known or unknown?

The sun - a star slightly above average in size - must have formed in an emission nebula some 5 billion years ago.


Does the nebula from which the sun emerged still exist?


Is it something that can only be speculated on for lack of information?

Even if the nebula has been dispersed, there would still exist highly detectable traces of the emission cloud would there not?

[escherspace]

When nebulas form stars they typically form a few high mass O and B stars along with lots of lower mass stars. These few bright stars blow apart the the remaining nebula with strong stellar winds and powerful UV light halting any further star formation. This process exposes an open cluster of young stars which slowly disperse due to internal gravitational interactions. The stars in that open cluster may be thrown out in different directions and at different speeds. Within a few hundred million years these stars will be dispersed around the disk of the galaxy. Even if there is primordial gas and dust left over in deep space from the nebula that formed our Sun, it is quite likely distributed around the galaxy in other stars and other nebulas and completely unidentifiable. Your question is akin to asking where you can find a cloud that you saw a couple years ago. While the water that formed the could may exist, it has combined and recombined in different forms and is distributed around the Earth in vapor, water, and ice. Our best chance of studying the primordial material of our birth nebula is looking at the oldest known objects in our Solar System: Carbonaceous chondrites and the material returned from a comet by NASA's Stardust mission.

[mcs]

I see, active nebulae are relatively short-lived. I'm surprised though at how quickly the left-over materials are dispersed, considering the highly structured spiral arms of the Milky Way.

Thanks for your answer.

[Westwind]

I remember reading that the Sun may have been created as part of a cluster of stars, and that these stars have since drifted away. The article mentioned that scientists think that stars created in a cluster with the Sun may be travelling through space along with the Sun on parallel tracks perhaps about 300 light years away. They are hoping to identify some of these "siblings" of the Sun by looking for properties and characteristics similar to the Sun--kind of like making a DNA match.

--Bill

[sarahstitcher]

I have a sort of related question, found this thread by searching on "open star cluster".
I have often wondered what the sky would look like to a person in a star cluster... Are the stars close enough together that it would never really get dark at night? (supposing a planet, which rotates so as to provide a night and day to its inhabitants) Would one see the other stars also during the day?

[The Code]

Hi sarahstitcher

I have a sort of related question, found this thread by searching on "open star cluster".
I have often wondered what the sky would look like to a person in a star cluster... Are the stars close enough together that it would never really get dark at night? (supposing a planet, which rotates so as to provide a night and day to its inhabitants) Would one see the other stars also during the day?

Interesting question. I always wondered what it would be like, to live on a planet that had two binary suns. I guess it could happen.

Mark

[RJN]

Interesting questions! There is a really great short story by Isaac Asimov titled "Nightfall" that describes in dramatic terms, and gripping fiction, what it might be like to live on a planet orbiting a star inside a multi-star system. It has been described as one of the best science fiction short stories of all time, but of course that is subjective. The Wikipedia link is here: http://en.wikipedia.org/wiki/Nightfall_ ... ort_story)

[neufer]

I always wondered what it would be like, to live on a planet that had two binary suns. I guess it could happen.

Planets around binary stars

<<Science fiction has often featured planets of binary or ternary stars as a setting. In reality, some orbital ranges are impossible for dynamical reasons (the planet would be expelled from its orbit relatively quickly, being either ejected from the system altogether or transferred to a more inner or outer orbital range), whilst other orbits present serious challenges for eventual biospheres because of likely extreme variations in surface temperature during different parts of the orbit. Planets that orbit just one star in a binary pair are said to have "S-type" orbits, whereas those that orbit around both stars have "P-type" or "circumbinary" orbits. A study of fourteen previously known planetary systems found three of these systems to be binary systems. All planets were found to be in S-type orbits around the primary star. In these three cases the secondary star was much dimmer than the primary and so was not previously detected.

It is estimated that 50–60% of binary stars are capable of supporting habitable terrestrial planets within stable orbital ranges. Simulations have shown that the presence of a binary companion can actually improve the rate of planet formation within stable orbital zones by "stirring up" the protoplanetary disk, increasing the accretion rate of the protoplanets within.

Detecting planets in multiple star systems introduces additional technical difficulties, which may be why they are only rarely found. Examples include PSR B1620-26 b and Gamma Cephei.

>>

[sarahstitcher]

so, do stars in an open cluster move in relation to each other? Such that the sky would look different to a planetary observer at different times?

[Chris Peterson]

so, do stars in an open cluster move in relation to each other? Such that the sky would look different to a planetary observer at different times?

Yes to both. In fact, the stars in open clusters are only loosely bound gravitationally, which means they need only a tiny bit of energy added to break away. As a result, open clusters are short lived, and evaporate over time.

[sarahstitcher]

wow, interesting. Do we know over how much time?

[Chris Peterson]

wow, interesting. Do we know over how much time?

It depends on the original density. Very loose clusters might survive only a few million years, but most open clusters probably hold together for a few hundred million years. Even after they break up, their stars may remain close enough together that we can see a relationship; the Big Dipper is believed to be a star stream that was once an open cluster (in a sense, it still is a cluster, but it's become so open that the term really isn't appropriate anymore).

[sarahstitcher]

thanks!

[Amir]

Is this known or unknown?
...
Does the nebula from which the sun emerged still exist?

is "Oort Cloud" irrelevant to this?

[Chris Peterson]

is "Oort Cloud" irrelevant to this?

Yes. The Oort cloud consists of material which condensed out of the progenitor gas and dust, along with the Sun and planets. It isn't the progenitor material itself.

[bystander]

Runaway star may have spawned the solar system
New Scientist - 2010 March 31

The solar system may have been born inside the remains of a single star that ran away from its family, rather than from a tight-knit clan of stars. If so, it may be more unusual than previously thought.

[bystander]

The Search for the Sun's Long Lost Siblings
Technology Review - 28 April 2010

Astronomers have published the results of the first serious search for stars that were born with the Sun.

Some 5 billion years ago, our Sun was born in a cloud of dust and gas, probably along with about 1000 other stars. These stars must now have a similar age and composition to Sol.

A study of these stellar siblings could answer important questions about the origin of the Solar System and the Sun. Their distribution would tell us where in the Milky Way the Sun has travelled during the last 5 billion years, how this journey might have effected the Earth's climate and the life it supports and their composition might explain why the Sun appears to have a higher metal content than expected for an object in this part of the galaxy.

So where are these siblings? Today, Anthony Brown at Missouri State University and a couple of pals publish the results of the first serious search for the Sun's siblings. And the results are disappointing.

The Quest for the Sun's Siblings: an Exploratory Search in the Hipparcos Catalogue

• arXiv.org > astro-ph > arXiv:1004.4284 > 24 April 2010

We describe the results of a search for the remnants of the Sun's birth cluster among stars in the Hipparcos Catalogue. This search is based on the predicted phase space distribution of the Sun's siblings from simple simulations of the orbits of the cluster stars in a smooth Galactic potential. For stars within 100 pc the simulations show that it is interesting to examine those that have small space motions relative to the Sun. From amongst the candidate siblings thus selected there are six stars with ages consistent with that of the Sun. Considering their radial velocities and abundances only one potential candidate, HIP 21158, remains but essentially the result of the search is negative. This is consistent with predictions by Portegies Zwart (2009) on the number of siblings near the Sun. We discuss the steps that should be taken in anticipation of the data from the Gaia mission in order to conduct fruitful searches for the Sun's siblings in the future.

[dougettinger]

The Search for the Sun's Long Lost Siblings
Technology Review - 28 April 2010

Astronomers have published the results of the first serious search for stars that were born with the Sun.

Some 5 billion years ago, our Sun was born in a cloud of dust and gas, probably along with about 1000 other stars. These stars must now have a similar age and composition to Sol.

A study of these stellar siblings could answer important questions about the origin of the Solar System and the Sun. Their distribution would tell us where in the Milky Way the Sun has travelled during the last 5 billion years, how this journey might have effected the Earth's climate and the life it supports and their composition might explain why the Sun appears to have a higher metal content than expected for an object in this part of the galaxy.

So where are these siblings? Today, Anthony Brown at Missouri State University and a couple of pals publish the results of the first serious search for the Sun's siblings. And the results are disappointing.

The Quest for the Sun's Siblings: an Exploratory Search in the Hipparcos Catalogue

• arXiv.org > astro-ph > arXiv:1004.4284 > 24 April 2010

We describe the results of a search for the remnants of the Sun's birth cluster among stars in the Hipparcos Catalogue. This search is based on the predicted phase space distribution of the Sun's siblings from simple simulations of the orbits of the cluster stars in a smooth Galactic potential. For stars within 100 pc the simulations show that it is interesting to examine those that have small space motions relative to the Sun. From amongst the candidate siblings thus selected there are six stars with ages consistent with that of the Sun. Considering their radial velocities and abundances only one potential candidate, HIP 21158, remains but essentially the result of the search is negative. This is consistent with predictions by Portegies Zwart (2009) on the number of siblings near the Sun. We discuss the steps that should be taken in anticipation of the data from the Gaia mission in order to conduct fruitful searches for the Sun's siblings in the future.

Why have astronomers originally thought that the Sun was part of a 1000-star cluster ? What parameters are needed for stars that form in clusters that single stars born in isolation do not have ?

Doug Ettinger
Pittsburgh, PA

[Chris Peterson]

Why have astronomers originally thought that the Sun was part of a 1000-star cluster ? What parameters are needed for stars that form in clusters that single stars born in isolation do not have ?

I'm not sure there are any stars born in isolation. If that happens at all, it must be under rare and unusual circumstances. We can directly observe many examples of star formation, and all are occurring in large nebulas that support hundreds or thousands of individual protostars. I expect the figure given for the Sun's siblings (1000) is just an estimate based on what we see elsewhere.

[dougettinger]

I am not that familiar with all the details of protostars forming in large nebulas. So what are the observed typical distances between these newly formed protostars ?

Doug Ettinger
Pittsburgh, PA

[Chris Peterson]

I am not that familiar with all the details of protostars forming in large nebulas. So what are the observed typical distances between these newly formed protostars ?

Images of star forming regions- Carina, Orion, Eagle, etc- show 10 to 100 protostars per cubic light year. These regions also have very hot, massive stars that are blowing away material even around other stars. You don't need to assume that small stars like the Sun are the only thing clearing out their own neighborhoods.

[dougettinger]

Thanks again for this enlightenment. The spacing would be approximately 12,000 AU's for 100 protostars per l.y.(3) - supposely less than the radius of the Oort Cloud from the Sun.

Doug Ettinger

[Chris Peterson]

Thanks again for this enlightenment. The spacing would be approximately 12,000 AU's for 100 protostars per l.y.(3) - supposely less than the radius of the Oort Cloud from the Sun.

Right. But keep in mind that as we see these stars in development, they are typically being ejected from the larger nebula, or otherwise spreading apart. And they are still in an early stage of development at that point- probably well before their planetary systems are formed. So the accretion of planets is probably occurring in a sparser environment.

[Beyond]

In reading through all these posts i am a little teeny bit surprised that no one has entertained the idea that this solar system just may have been put together puposefully sometime "BEFORE" THIS Earth was added.
I think it was Carl Seagan(did i spell it right?)on PBS that was explaining how intricately all the things in the Solar System and somewhat beyond, work together for there to be "life" on this third rock from the Sun. Things like that just do not happen by accident.

It could very well be that we just have not as yet noticed that we are 'inside' Superforces that are of such magnitude we just do not reconize the things that they do.

To me -- it very well could be that a long time ago in a place far away, Superforces designed and created this solar system and designed and created this Earth and put them together and launched everything to arrive at a certain point sometime in the future.

I find that the more things are searched out - the stranger they are and the more 'normal' they become.

[neufer]

To me -- it very well could be that a long time ago in a place far away, Superforces designed and created this solar system and designed and created this Earth and put them together and launched everything to arrive at a certain point sometime in the future.

• What? I don't understand.

<<Magrathea is an ancient planet located in orbit around the twin suns Soulianis and Rahm in the heart of the Horsehead nebula. Magrathea is a planet whose economy was based on the manufacturing of other planets for the wealthiest people in the universe. Amongst the clients who asked for planets to be created were a race of hyper-intelligent pan-dimensional beings who asked the Magratheans to create the Earth which, in addition to being a planet, was a super-computer designed to calculate the ultimate question to the ultimate answer to life, the universe, and everything. Amongst the people who worked on it was SlARTibARTfast, a coastal designer who won an award for his work on Norway.>>

• Pre-SlARTibARTfast Euro:

<<Frankie and Benjy are the mice that Arthur encounter on Magrathea. Frankie and Benjy wish to extract the final readout data from Arthur's brain to get the Ultimate Question. Frankie and Benjy are, after all, part of the pan-dimensional race that created the Earth as a supercomputer successor to Deep Thought in order to find out the question to which the answer was 42.

Unfortunately for Arthur, they claim the only way to do this is to remove his brain and prepare it, apparently by dicing it. They promise to replace it with a simple computer brain, which, suggested Zaphod, would only have to say things like "What?", "I don't understand." and "Where's the tea?". Arthur objects to this ("What?", he says. "See!" says Zaphod), and escapes with the help of his friends. Frankie says:

• "I mean, yes idealism, yes the dignity of pure research, yes, the pursuit of truth in all its forms, but there comes a point I'm afraid where you begin to suspect that if there's any real truth it's that the entire multi-dimensional infinity of the Universe is almost certainly being run by a bunch of maniacs; and if it comes to a choice between spending another ten million years finding that out and on the other hand just taking the money and running, I for one could do with the exercise.">>

---------------------------------

Arthur (Where's the tea?) Neuendorffer