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I read somewhere a long time ago that there is enough matter in our solar system in the form of rocks and dust to create another sun.Is this correct? Was our solar system trying to create a 2 star system?

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    $\begingroup$ If you have an advanced civilization able to "make a sun", you can do starlifting to extract material from the original Sun for that purpose. As it becomes smaller, it will become less bright, and longer-living. (Though then the question is better for worldbuilding.SE.) $\endgroup$ Commented Dec 18, 2022 at 22:43
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    $\begingroup$ What does "orbiting the sun" mean to you? Is that out to the orbit of Pluto, or only of Neptune? Either way, what do you see as the mass of the sun, and of the rest of the system? $\endgroup$ Commented Dec 19, 2022 at 2:02
  • $\begingroup$ Although the solar system doesn't currently have enough extra mass to form an additional star, star formation is a complex process which typically generates multiple stars together ( abyss.uoregon.edu/~js/ast122/lectures/lec13.html ) and some of the initial matter can be slung out of the individual star systems, although it's unlikely that our particular solar system ever had enough for two stars: phys.org/news/2015-10-minimum-mass-proto-solar-disk.html $\endgroup$ Commented Dec 19, 2022 at 15:02
  • $\begingroup$ Can you say where "Was our solar system trying to create a 2 star system?" comes from? That doesn't seem related to the OQ. $\endgroup$ Commented Dec 21, 2022 at 0:17
  • $\begingroup$ @RobbieGoodwin, "orbiting the Sun" generally means something that is gravitationally bound, rather than referring to a specific distance. $\endgroup$
    – Mark
    Commented Dec 21, 2022 at 3:32

2 Answers 2

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The vast majority of the stuff in the solar system other than the Sun itself is contained in one body, Jupiter. The total mass of the solar system is estimated to be about 1.0014 solar masses, or about one solar mass plus 1.4 Jupiter masses. (Jupiter's mass is a bit less than 0.001 solar masses.) Using the highest estimates on the mass of the Oort cloud, the total mass of the solar system, excluding the Sun itself, is about 30 Jupiter masses. These early estimates have been shown to be wrong. Current estimates are that the mass of the Oort cloud is one or two Earth masses. Even if the hypothesized planet IX does exist and is as large as some hypothesize (about five Earth masses), that will only budge the estimated 1.0014 solar masses by a tiny, tiny bit.

The smallest possible star, defined as something capable of fusing hydrogen, is about 65 to 80 Jupiter masses. The answer is no.

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    $\begingroup$ And a good part of that matter wouldn't be useful for forming a star as it's not useful as fusion fuel (in fact would poison the fusion process). Which is one reason stars die, their fusion process gets poisoned by heavy isotopes. $\endgroup$
    – jwenting
    Commented Dec 19, 2022 at 8:03
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    $\begingroup$ @Panzercrisis wolframalpha.com/… $\endgroup$ Commented Dec 19, 2022 at 13:33
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    $\begingroup$ @Panzercrisis The mass of the smallest possible star is typically stated in terms of Jupiter's mass rather than the Sun's mass. There are many good reasons for this. $\endgroup$ Commented Dec 19, 2022 at 13:35
  • $\begingroup$ @Panzercrisis 0.001% --> 0.00001, I think the % sign is an error there, or it should be 0.1%. $\endgroup$
    – Nick T
    Commented Dec 20, 2022 at 0:49
  • $\begingroup$ @NickT Okay, yeah, that must've been a typo. $\endgroup$ Commented Dec 20, 2022 at 12:14
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No. The total mass of the planets, asteroids, dust etc in the solar system is only about 0.1% of the mass of the sun. There is not nearly enough to make even a small star.

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    $\begingroup$ 0.1 % is about 330 Earth masses . $\endgroup$
    – user48394
    Commented Dec 18, 2022 at 1:11
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    $\begingroup$ @DaveTheWave That's not nearly enough. A better number is 0.0014 Sun masses, or about 1.4 Jupiter masses. The smallest possible star is 65 to 80 Jupiter masses, depending on who one reads. $\endgroup$ Commented Dec 18, 2022 at 4:24
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    $\begingroup$ I'm not sure that counts as "rocks and dust". On the other hand, I'm not sure if planets count as "rocks and dust". However, no matter which way you cut it, there isn't enough "stuff" for a second star. $\endgroup$
    – James K
    Commented Dec 18, 2022 at 20:12
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    $\begingroup$ @Michael 1000 Earth masses is a bit more than 3 Jupiter masses, so not enough stuff to cut it. Moreover, the Sun and the planets are very good at either expelling small material from the solar system or making such material drop into the Sun. (The zodiacal light falls into the latter category.) Even if what you wrote is true (which it isn't), an additional three Jupiter masses will not cut it. $\endgroup$ Commented Dec 19, 2022 at 13:47
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    $\begingroup$ @Michael I suspect your number is too large by a factor of $10^8$. The vast majority of protons in interplanetary space come from the Sun (aka the solar wind, which arises from things such as sunspots and coronal mass ejections). The density of those solar emissions drops with the square of distance from the Sun. Moreover, it is not spherically symmetrical. The majority of those particles are near the plane of the Sun's equator. (continued) $\endgroup$ Commented Dec 20, 2022 at 8:49

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