How to find Sun's Sibling Stars, Exo-Planets

[Widdekind]

According to the History Channel documentary The Universe -- The Milky Way (TV), Open Clusters are loosely bound groups of hundreds to thousands of stars, in the Galactic Disk, which all formed from the same Giant Molecular Cloud (GMC). Thus, once the star formation process has consumed, and dispersed, the parent GMC's gas & dust, what remains is an Open Cluster of stars, as loosely gravitationally bound to each other, as the original GMC. The Sun surely formed from such a GMC, and so surely formed amidst many other stars, in an Open Cluster, which slowly dispersed over the course of roughly 300 million years (~1-2 Galactic Orbits).

CONCLUSIONS:

Surely, the Sun has hundreds of "stellar siblings", long-lost brothers now dispersed about the Galactic Disk. But, since all those stars formed from the same parent GMC, they surely have:

• the same Age as the Sun (~4.6 billion years)
• the same Metallicity as the Sun (Z ~0.02)

They may also all have similar Galactic Orbital Radii, unless Peculiar Motions carried some of them far away from their birth-places. Moreover, knowing Initial Mass Function of stars formed in the Milky Way*, we can accurately guess how many stars of each mass there "should" be (unless the IMF was different ~4.6 billion years ago).

* [Registered users can see links. ]. The IMF essentially estimates the relative ratios, of the numbers of stars, of various masses, which form in the Milky Way. Thus, there "should" be (say) 3 K-Class stars, for every 2 G-Class stars, for every 1 F-Class star.

Thus, by picking out all the Galactic Disk stars of Solar Age & Metallicity(& Galactic Orbital Radius ??), the Sun's "stellar family" can be reconstructed:

And, since the Sun formed planets, which were seeded w/ Life, the Sun's "stellar siblings" seem like likely candidates for Extra-Solar Planetary Systems, housing Extra-Solar Lifeforms.

This process would also indicate the dynamics of the Galactic Disk, showing how Open Clusters disperse over ~4.6 billion years.

[Widdekind]

Since stellar interactions can kick Comets out of the Oort Cloud, and careening into the Inner Solar System, the Sun's "stellar siblings" may be responsible for the Late Heavy Bombardment of the Hadean Eon (~4.6 to 3.8 billion years ago)*.

* [Registered users can see links. ]

[Widdekind]

Astronomers can identify the fragments of past Asteroids, dispersed by catastrophic collisions:

An Asteroid Family is a population of asteroids that share similar orbital elements, such as Semimajor Axis, Eccentricity, & Orbital Inclination. The members of the families are thought to be fragments of past asteroid collisions*.

Similar such procedures could surely be used to identify "Stellar Families", of past Open Clusters, dispersed by the vicissitudes of time (eg. Stellar Families might share similar Galactic Orbital Radii & Periods). Not only could such procedures identify the Sun's Stellar Siblings, but, b/c essentially every star in the Galactic Disk surely formed from GMCs, being born in Open Clusters, much of the whole stellar population of the Galactic Disk could be broken down into groups of dispersed, past, Open Clusters (!).

* [Registered users can see links. ]

[Widdekind]

Earth Lifeforms, from Bacteria to Mammals, most resemble Inter-Stellar Frost & Volatiles from Comets*. Conversely, Earth Lifeforms do not resemble the Chemical Composition of this planet:

Is Silicon abundant enough on Earth to support life? It is -- in fact, in 135 times more abundant than Carbon. If we look into the Universe, however, we find that Silicon is not particularly abundant; considerably less than 1 percent of the Universe is made up of it. Nevertheless, b/c it is common on Earth, we could assume that it would be common on planets beyond the Solar System**.

This strongly suggests, that Life first started in Deep Space, and was seeded onto Earth by Life-bearing, Long-Period (ie., Inter-Stellar) Comets (Panspermia***).

* J. William Schopf. Life's Origin, pg. 15.
** Barry Parker. Alien Life, pg. 45.
*** cf. Prof. Chandra Wickramasinghe.

CONCLUSION:

The Sun's parent GMC contained Life-bearing Comets, which seeded our Solar System w/ primitive microbes. Over roughly 4.6 billion years of evolution, those primitive microbes have developed & become Mammals & modern Humans*.

* Modern Complex Lifeforms on Earth are, at root, "evolved Alien bacteria".

This strongly suggests, that all the Sun's Stellar Siblings were also so seeded, with Life-bearing Comets, making them likely candidates for Alien Lifeforms*.

* Furthermore, once Astronomers begin grouping Galactic Disk stars into their Stellar Families, then the detection of Alien Life on any one member of such a Stellar Family would make all its Stellar Siblings likely candidates for more Alien Lifeforms.

[Widdekind]

[Registered users can see links. ]

Sun's siblings may have seeded Earth life

Most of the stars in the Milky Way got their start in clouds of dust and gas that eventually formed clusters of stars. If our Sun started life in such a scenario, the cluster would most likely have drifted apart after a few hundred million years.

But that might have been enough time for life to travel between the rocky debris surrounding each nascent star, according to a study led by astronomer Mauri Valtonen at the Turku University in Finland.

Rock-smashing experiments have suggested that microbes could certainly survive a massive crash that sandwiches them in debris and jettisons them into space.

And a recent study by Edward Belbruno and colleagues at Princeton University showed that planets in densely packed star clusters could throw out as many as 10^18 rocks in the first 100 million years or so, at speeds slow enough for other stars to capture them.

The new research suggests that microbes from other planetary systems, if they existed, could very well have hitched a ride in such rocks - as long as the rocks were large enough to protect the organisms from cosmic rays and the heat of impact. If the Sun was born in a cluster, there would have been time for around 100 life-bearing rocks to be captured by our star before the cluster drifted apart, the researchers say.

Belbruno notes one reservation about the result: rocks moving slowly enough to be captured by other stars will take tens of millions of years [cf. above, Open Clusters remain bound for hundreds of millions of years] to reach their neighbours. It is unknown whether microbes can survive that long in interstellar space, he points out.

Nevertheless, Valtonen's result means we might improve our chances of finding something similar to terrestrial life if we can track down the Sun's former siblings.

[Widdekind]

(1) Stars orbit Galactic Center in regular, ellipsoidal orbits

[Registered users can see links. ]

As Francis describes it, the Milky Way and other spiral galaxies operate like a giant, spiral-grooved funnel into which billions of marbles are pouring. The grooves represent the gravitational field of the galaxy's spiral arms. Each marble finds a groove at the top of the funnel and begins to follow it down a never-ending slope, picking up momentum as it goes. Eventually, the marble gains enough momentum to jump free of its groove. It crosses to the next-highest one then falls back to a higher point in its original groove. (Watch the process [Registered users can see links. ].)

(2) Stellar "Metallicity - Mix" fingerprints Time & Place of stars' formations

Metallicity is not the only compositional prerequisite for Habitable Planets — the relative abundances of different elements matter, too. The most abundant elements on Earth were produced primarily in Supernova explosions, of which there are two basic types. Type I events, most of which result from the detonation of a White Dwarf star, produce mainly iron, nickel & cobalt. Type II Supernovae, which entail the implosion of a massive star, mostly synthesize oxygen, silicon magnesium, calcium & titanium. Crucially, Type II events are also the sole natural source of the very heavieest elements, such as thorium & uranium.

B/c Star Formation in our Galaxy is tapering off, the overall rate of Supernova explosions is declining — as is the ratio of Type II to Type I events. Type II Supernovae involve short-lived, massive stars, so their rate closely tracks the Star Formation Rate. The rate of Type I Supernovae, on the other hand, depends upon the production of longer-lived, intermediate mass stars, so it responds more slowly to changes in the Star Formation Rate.

As a result of the shifting Supernovae Ratio, new sunlike stars are richer in iron than those formed 5 billion years ago. All else being equal, this implies that a terrestrial planet forming today will have a proportionately larger iron core than Earth does. It will also have, in 4.5 billion years, about 40% less heat from the decay of potassium, thorium & uranium. The heat generated by these radioactive isotopes is what drives Plate Tectonics, which plays an essential role in the Geochemical Cycle that regulates the amount of carbon dioxide in our atmosphere.

Guillermo Gonzalez, Donald Brownlee, & Peter D. Ward. Refuges for Life in a Hostile Universe. Printed in: [Scientific American] Majestic Universe, pp. 8-9.

CONCLUSION:

"Stellar Sibkos" can be tracked exactly like Asteroid Families — by their Semi-Major Axes (about the Galactic Core) & Orbital Inclination, as well as their particular "Metallicity-Mixes".

[Widdekind]

A pair of articles from Scientific American, precisely to this point:

[Registered users can see links. ]

• 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.

[Registered users can see links. ]

Until now, mainstream astronomers have dismissed the idea of actually finding any of our wayward kin, some 4.3 billion years after our stellar birth cluster is believed to have dissipated. But Portegies Zwart, in a new paper (being reviewed for publication in Astrophysical Journal Letters), offers up what may be a credible way to find 50 or 60 of our own sun's original siblings, that small fraction of the estimated 1,000 to 6,000 original cluster members Portegies Zwart thinks is located within some 300 light-years of Earth.

Portegies Zwart proposes identifying stellar relatives via their proper motion, or apparent movement across our line of sight, their position in the sky, and their chemical signatures, which he likens to their stellar DNA. Such stars, he says, would be roughly one solar mass (the size of the sun) or less and have chemical abundances similar to the sun.

[GriffinBF]

It's probably best to just post the links.. or give us the gist of it.

[Widdekind]

Does it help to highlight important phrases in color ?

[emc2cracker]

I found this forum researching finding the suns siblings, I have been studying this paper here which I found a wealth of info:

bah first post I can't post links but you can google it

THE LOST SIBLINGS OF THE SUN
SIMON F. PORTEGIES ZWART
Astronomical Institute ‘Anton Pannekoek’, University of Amsterdam, Kruislaan 403, Amsterdam, the Netherlands
Institute for Computer Science, University of Amsterdam, Kruislaan 403, Amsterdam, the Netherlands
Sterrewacht Leiden University of Leiden, Niels Bohrweg 2, 2333 CA Leiden, the Netherlands
Draft version March 2, 2009

I did not know that our sun was exposed to a supernova shortly after birth, this probably explains our high metallicity compared to other star systems.