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Ammonia
2010-Mar-04, 12:03 PM
I once saw in tv docu that our sun is the second generation star to occupy this area of space that our solar system and beyond are in.

This is proved by the amount of heavy elements in our sun which must of originated from the matter of a nearby supernova or from the matter given off when a star is dying.

Could the remnant of this dead star like a brown dwarf or black hole be nearby our space like say 1-10 light years away but they cannot be seen?

What about the gravity effects created by this brown dwarf or black hole they would be seen on other seen stellar objects such as nearby stars like the alpha system?

mmaayeh
2010-Mar-04, 12:19 PM
I think a brown dwarf (a failed star -- never had a chance to be a star but a very large version of Jupiter) would be hard to see, I would imagine, even at 1 light year. I hope the new space telescopes can begin to detect these faint objects. I know we are still trying to find the Oort cloud and that is something like 1/3 of the way from our Sun to Alpha Centauri (4.5 light years away so that is something like 1.5 light years or less to the Oort cloud from the Sun).

The black hole if it is 1 light year away or out to 10 light years away I would imagine you would indirectly detect it via gravitational lensing as I think we would always see some sort of distortion at some point in our sky as the light is coming from other parts of the universe towards us. However, I am not certain how much of a gravitational affect is caused on our Solar System if it is about 1 light year away. I would imagine not too much, if any. Perhaps others can help answer this question.

drhex
2010-Mar-04, 12:19 PM
A brown dwarf is something between a large planet and a small star that has never started proper fusion in its core.
The stars that gave our solar system its metals may be black holes by now, but if they were as nearby as a few lightyears we would surely have noticed them.

Hornblower
2010-Mar-04, 12:58 PM
The Sun's age is estimated to be some 5 billion years. That is plenty of time for the remnants of the metal sources (supernovae, etc.) to be scattered far and wide. The chances of finding one within a few light years would be rather small, in my opinion.

01101001
2010-Mar-04, 01:53 PM
Could the remnant of this dead star like a brown dwarf or black hole be nearby our space like say 1-10 light years away but they cannot be seen?

No.

Our current neighbors came from all over the galaxy. Our sibling stars are scattered all over the galaxy. Our mother stars' remnants are scattered even more. (And their cores didn't survive as brown dwarfs.)

Space.com: The Crazy Cosmos: Stars Near Sun are Wild & Wayward (http://www.space.com/scienceastronomy/milkyway_movement_040406.html)


A new survey of stars near the Sun reveals a wild and crazy past in which wanderers arrived from all directions under the gravitational influences of black holes, clouds of gas and invading galaxies.

Animation (http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=040406_milkyway_anim_02.gif) shows the Sun's last 250-million-year orbit around the center of the galaxy (GC), and other stars converging toward the Sun, ending with all of them nearer the Sun today. Credit: ESO

Our sun has made about 25 blender-mixing trips around the galaxy.

Edit: Animation may not display. Small version is in sidebar to linked article.

BigDon
2010-Mar-04, 02:47 PM
Binaryman, that reply was a gem among a career of notable replies.

EDG
2010-Mar-04, 05:09 PM
Space.com: The Crazy Cosmos: Stars Near Sun are Wild & Wayward (http://www.space.com/scienceastronomy/milkyway_movement_040406.html)

Edit: Animation may not display. Small version is in sidebar to linked article.

I couldn't get any of the images to load from that article at all.

astromark
2010-Mar-04, 06:58 PM
@ the OP, Ammonia ; From this vantage point on the edge of a spiral arm three quarters of the way out from the center of the 'Milky Way' This Solar system is just bobbling along its wobbly path around the central mass of this Galaxy. That this star Sol is the product of co-lessing matter spent from a nova event sheparded by stellar shock waves some five billion years ago. That in the chaotic past encounters with other like objects is common and expected. NO. Do not expect to find black holes or even brown failed stars near here. The term 'near here' is confusing. On astronomical scales twenty ly is close... Our very short window of knowledge narrows our view.

EDG
2010-Mar-04, 08:42 PM
Do not expect to find black holes or even brown failed stars near here.

While there are no black holes nearby, we do know of some brown dwarfs in our vicinity (e.g. LP 944-20 (http://www.solstation.com/stars/lp944-20.htm). DENIS 1048-39 (http://www.solstation.com/stars/d1048-39.htm) may be another Brown Dwarf too). There are probably more, but they are very hard to detect due to their dimness and low mass.

These aren't really "dead stars" though, they're substellar objects that don't form as a result of the end of a star's lifecycle.

astromark
2010-Mar-05, 02:52 AM
Time and a little research brings me to altar my '. Not round here stance'. :)Yes there could be a list of near to earth Brown Dwarfs...Proxima Centari, like objects..
Some I would dare call failed stars... The OP asks of 1-10 ly. objects. With the improved equipment levels I have little doubt we will find objects in the interstellar space not to far from here. As has been well covered. I do not expect any object to hold a significant threat to Earth... and, No, to the black hole idea.

EDG
2010-Mar-05, 06:48 AM
The answer to the OP's question (as the binary guy indicated) is that any supernova explosions that enriched our protosolar nebula are long gone. The sun is 4.6 billion years old, and takes about 250 million years to orbit the galaxy - so in its entire lifetime it has completed 18.4 orbits around the galaxy. Not only that, but everything else in its vicinity at its formatio has also completed many orbits around the galaxy (not necessarily on the same sort of path as Sol either - some stars would have had more eccentric orbits, or less eccentric orbits, or may have gravitationally interacted with eachother and got disturbed into different orbits... heck, Sol itself may have interacted with other stars and had its orbit changed too).

So essentially we have absolutely no idea where any stars that were near us when Sol formed are in the galaxy today, and no accurate way to trace Sol's path back in the past either. Also, while the neutron star or black hole formed by the supernova is probably still around somewhere in the galaxy (assuming it hasn't been ejected from the galaxy by a gravitational interaction, that is), the more visible nebula around the stellar remnant has long since dissipated away after 4.6 billion years, so it'd be pretty much impossible to find the remnant anyway.

EDIT: (oh, and the pictures are working in the Space.com article for me now. Cool animation there).

01101001
2010-Mar-05, 08:13 AM
I couldn't get any of the images to load from that article at all.

Too bad. It was an old article. Glad it eventually worked. I've posted links to it here now and then. It was fascinating, showing the Sun's current neighbors in their locations a Sun-galactic rotation ago, spread in an arc around half the galaxy, and the positions between then and now.

Suffice to say the Sun's current neighbors were mostly far-distant strangers just one revolution ago. And dozens of revolutions, well, you can imagine: like a splash of cream thoroughly stirred into a cup of coffee.

01101001
2010-Mar-05, 08:22 AM
So essentially we have absolutely no idea where any stars that were near us when Sol formed are in the galaxy today, and no accurate way to trace Sol's path back in the past either.

But I do think they made some progress in identifying the Sun's siblings by their chemical makeup, or at least knowing enough to begin the search. Maybe.

NewScientist: How to find the Sun's long-lost siblings (http://www.newscientist.com/article/mg20126994.100-how-to-find-the-suns-longlost-siblings.html)


But over the last few billion years, these stars have gone their separate ways, blending in among the galaxy's myriad background stars.

Simon Portegies Zwart of the University of Amsterdam in the Netherlands suggests a way to find them.
[...]
He found that a few percent of the siblings should still be in our cosmic vicinity, in the constellations Cygnus and Vela, both within 300 light years (see this illustration).

Siblings in the vicinity, but not real close. Others disagree. Parents long gone.

neilzero
2010-Mar-05, 02:48 PM
Since we lose most of the nearby stars in about 200 million years that means we have acquired 23 new sets of close stars, since our Earth was formed. Among those several black holes and neutron stars with negligible accretion disks, have likely been closer than ten light years. As some one typed, lensing should betray the presence of any that close and neutron stars will mostly produce enough visable light to be seen ten light years away. Are any neutron stars formed 13 billion years ago now cooler than 1000 degrees k? Neil

IsaacKuo
2010-Mar-05, 02:51 PM
Anyway, to answer the OP's unspoken question--there are three types of "dead star", that we know of:

1) White dwarf. This is not the result of a supernova, but it's the fate of most stars. There are numerous white dwarfs in our neighborhood, but they are visible to us because they haven't had much time to cool down. I'm not sure, but I think it's possible that an old white dwarf could have cooled down enough to make it hard for us to see even within 10ly.

2) Neutron star. This is one possible result from a supernova, and one that's billions of years old would be extremely hard for us to see unless it were recently spun up (into a pulsar) or if it had an accretion disc.

3) Black hole. This is another possible result from a supernova, and it would be even harder to see than a neutron star. It's only visible if it has an accretion disc.

chornedsnorkack
2010-Mar-05, 04:24 PM
Anyway, to answer the OP's unspoken question--there are three types of "dead star", that we know of:

1) White dwarf. This is not the result of a supernova, but it's the fate of most stars. There are numerous white dwarfs in our neighborhood, but they are visible to us because they haven't had much time to cool down. I'm not sure, but I think it's possible that an old white dwarf could have cooled down enough to make it hard for us to see even within 10ly.


Old white dwarfs are supposed to be around 4000 K now.

antoniseb
2010-Mar-05, 08:27 PM
Nearby old neutron stars and black holes would most likely be quite visible as SGRs (Soft Gamma Repeaters).

chornedsnorkack
2010-Mar-05, 10:32 PM
Nearby old neutron stars and black holes would most likely be quite visible as SGRs (Soft Gamma Repeaters).

I heard that soft gamma repeaters seem to be young magnetars.

Hornblower
2010-Mar-05, 11:30 PM
The answer to the OP's question (as the binary guy indicated) is that any supernova explosions that enriched our protosolar nebula are long gone. The sun is 4.6 billion years old, and takes about 250 million years to orbit the galaxy - so in its entire lifetime it has completed 18.4 orbits around the galaxy. Not only that, but everything else in its vicinity at its formatio has also completed many orbits around the galaxy (not necessarily on the same sort of path as Sol either - some stars would have had more eccentric orbits, or less eccentric orbits, or may have gravitationally interacted with eachother and got disturbed into different orbits... heck, Sol itself may have interacted with other stars and had its orbit changed too).

So essentially we have absolutely no idea where any stars that were near us when Sol formed are in the galaxy today, and no accurate way to trace Sol's path back in the past either. Also, while the neutron star or black hole formed by the supernova is probably still around somewhere in the galaxy (assuming it hasn't been ejected from the galaxy by a gravitational interaction, that is), the more visible nebula around the stellar remnant has long since dissipated away after 4.6 billion years, so it'd be pretty much impossible to find the remnant anyway.

EDIT: (oh, and the pictures are working in the Space.com article for me now. Cool animation there).

My bold for reference. "The" supernova? For all we know the dusty gas cloud from which our Sun formed may have had a mixture of ejecta from numerous supernovae that had blown over the previous few billions of years.

EDG
2010-Mar-06, 02:07 AM
My bold for reference. "The" supernova? For all we know the dusty gas cloud from which our Sun formed may have had a mixture of ejecta from numerous supernovae that had blown over the previous few billions of years.

Sure, but I thought the OP was referring to the supernova that's often mentioned that is supposed to have triggered the collapse of the cloud into the sun and its planets.

Either way, whether it's plural or singular doesn't change the point, which is that we have no idea where anything that either contributed to the cloud or caused it to collapse could be in the galaxy now.