<p>From a comment by <a href="https://astronomy.stackexchange.com/users/21/barrycarter">barrycarter</a>: </p>

<blockquote>
  <p>In our galaxy, it might be <a href="https://www.jpl.nasa.gov/news/news.php?feature=6578" rel="nofollow noreferrer">CX330</a>, which is 1000 light years from any star-forming region, much less any star. However, the article describes it as "Loneliest Young Star", so there may be older stars that are even more isolated. <a href="https://www.smh.com.au/technology/cx330-galaxys-loneliest-baby-star-discovered-wandering-far-from-stellar-nurseries-20160728-gqfg1i.html" rel="nofollow noreferrer">This source</a> contains the phrase "CX330 [...] has been described as the galaxy's loneliest star.", but this may just be bad reporting.</p>
</blockquote>

CC BY-SA 4.0
2018-10-11T18:28:53.780Z
2018-10-11T18:28:53.780Z
rob
<p>I don't think anyone knows the answer to this! People have only recently started looking at the Gaia catalogues and they contain so much data that most of it won't get looked at unless it is in an interesting area. Astronomers have started combing through the data seeing what we can find in our favourite regions but most people focus on the more densely populated areas (clusters and places where stars are forming) rather than the mainly empty areas (probably older stars not interacting with each other).</p>

<p>So I think this is something you could find in the catalogue, the information does exist, but no one is particularly interested in spending a lot of time looking for it because we won't learn much from those regions.</p>

CC BY-SA 4.0
2018-09-16T08:10:51.913Z
One would not "look" for it, but rather write a program to sift through the data to find the star furthest away. That is in itself a fun programming problem since the catalogue is so large that it is hard to keep it all in memory at the same time for a normal PC: some cleverness is needed to handle the search problem.
Anders Sandberg
CC BY-SA 4.0
2018-09-11T14:09:55.347Z
2018-09-11T14:09:55.347Z
FJC
<p>This is just a matter of curiosity; I was thinking about a scifi story. </p>

<p>By "Isolated", I mean that if for every star (or binary) we found the distance to its closest neighboring star, then which one would be the <strong>furthest</strong> from its closest neighbor?</p>

CC BY-SA 4.0
2018-09-10T14:08:05.320Z
That assumes that we know the location of every star in the Milky Way -- all 250 (+/- 150) billion of them. Since we can't see most of them, I'd say that your question is impossible to answer.
Mick
CC BY-SA 4.0
2018-09-10T14:19:43.900Z
@Mick Okay. How about the most isolated amongst KNOWN stars?
Amadeus
CC BY-SA 4.0
2018-09-10T16:20:46.587Z
Even amongst known stars in our galactic neighborhood, it would be hard to tell, because a known star could have a neighbor that we don't know about because it is fainter. Also, different regions of our galaxy have different densities of stars. For example, if you go away from the galactic plane, the density decreases, same for the arms, and away from the outer arms, eventually you reach the intergalactic region that has very few stars.
FSimardGIS
CC BY-SA 4.0
2018-09-10T16:28:06.587Z
@FSimardGIS Wouldn't stars in the intergalactic region not be PART of the Milky Way? At some point they aren't rotating around our center, I should think those are rogue stars, or in another galaxy (which might be a mini galaxy rotating about the Milky Way, but isn't IN the Milky Way). Perhaps stars between arms near the outer edge of the Milky way are candidates. Also, if you know the density decreases, there must be some numbers for that, and the simulated images of the Milky Way that show the structure of it must be based upon some rather accurate distance measurements of actual stars.
Amadeus
CC BY-SA 4.0
2018-09-10T16:43:19.933Z
Indeed, the intergalactic region isn't part of the Milky Way, but the "border" of the galaxy is rather fuzzy and hard to know. I haven't found any reference that defines that border, nor any model that shows densities for different regions, just general numbers, like [this](http://assets.zombal.com/03a5cab4/GalaxyDensity.pdf) for example.
FSimardGIS
CC BY-SA 4.0
2018-09-11T01:16:46.050Z
@Amadeus A more answerable question might be "Of the stars in the Gaia / Hipparchos catalogs, which one is the most isolated (as defined in your question here)?"
Alphecca
CC BY-SA 4.0
2018-09-11T18:27:12.457Z
@barrycarter Go for it and post an answer. I'd be interested to know what you find out.
Alphecca
CC BY-SA 4.0
2018-09-11T22:48:02.727Z
@barrycarter  The Gaia DR2 catalogue contains parallaxes for hundreds of millions of stars.
ProfRob
CC BY-SA 4.0
2018-09-12T05:18:51.113Z
Since this is for a story, I assume you want a star that's relatively friendly to life as we know it. So a white dwarf that got thrown to the galactic rim in the aftermath of the supernova of its former partner is  probably not what you want. Similarly, a red giant system may be undesirable, since it'd be pretty hard to survive your sun going red giant.
PM 2Ring
CC BY-SA 4.0
2018-09-12T10:52:58.493Z
@PM2Ring If a star is undergoing fusion, doesn't it have SOME Goldilocks  temperature zone between 5C and 30C relatively friendly to life? For a captured planet, a relocated planet, or some other artificial construct like a giant space station orbiting in the zone? I think it just needs to be a source of radiative power; for perhaps an intentionally remote research station (for security and safety purposes while developing a new technology).
Amadeus
CC BY-SA 4.0
2018-09-12T11:53:58.817Z
Oh, ok. Still, a red giant system isn't a fun place to live. Their output can be quite variable, and they can spew out an awful lot of dust. But I guess if you can't migrate to another system you have to make do with what you've got.
PM 2Ring
CC BY-SA 4.0
2018-09-12T20:02:25.643Z
@barrycarter That one (CX330) is pretty interesting. I presume if it could form, so could a sun-like star, with planets...
Amadeus
CC BY-SA 4.0
2018-10-12T03:51:59.030Z
@barrycarter What is the uncertainty in the distance compared to the average spacing between stars?
Keith McClary
<distances><milky-way>
Of the stars in the Gaia / Hipparchos catalogs, which one is the most isolated?
Amadeus
# Of the stars in the Gaia / Hipparchos catalogs, which one is the most isolated?

(Asked by: username_0 on 2018-09-10)

This is just a matter of curiosity; I was thinking about a scifi story.

By "Isolated", I mean that if for every star (or binary) we found the distance to its closest neighboring star, then which one would be the **furthest** from its closest neighbor?

**Tags:** distances, milky-way
> **Comments:**
> **username_1**: That assumes that we know the location of every star in the Milky Way -- all 250 (+/- 150) billion of them. Since we can't see most of them, I'd say that your question is impossible to answer.  
> **username_0**: @Mick Okay. How about the most isolated amongst KNOWN stars?  
> **username_2**: Even amongst known stars in our galactic neighborhood, it would be hard to tell, because a known star could have a neighbor that we don't know about because it is fainter. Also, different regions of our galaxy have different densities of stars. For example, if you go away from the galactic plane, the density decreases, same for the arms, and away from the outer arms, eventually you reach the intergalactic region that has very few stars.  
> **username_0**: @FSimardGIS Wouldn't stars in the intergalactic region not be PART of the Milky Way? At some point they aren't rotating around our center, I should think those are rogue stars, or in another galaxy (which might be a mini galaxy rotating about the Milky Way, but isn't IN the Milky Way). Perhaps stars between arms near the outer edge of the Milky way are candidates. Also, if you know the density decreases, there must be some numbers for that, and the simulated images of the Milky Way that show the structure of it must be based upon some rather accurate distance measurements of actual stars.  
> **username_2**: Indeed, the intergalactic region isn't part of the Milky Way, but the "border" of the galaxy is rather fuzzy and hard to know. I haven't found any reference that defines that border, nor any model that shows densities for different regions, just general numbers, like [this](http://assets.zombal.com/03a5cab4/GalaxyDensity.pdf) for example.  
> **username_3**: @Amadeus A more answerable question might be "Of the stars in the Gaia / Hipparchos catalogs, which one is the most isolated (as defined in your question here)?"  
> **username_3**: @barrycarter Go for it and post an answer. I'd be interested to know what you find out.  
> **username_4**: @barrycarter  The Gaia DR2 catalogue contains parallaxes for hundreds of millions of stars.  
> **username_5**: Since this is for a story, I assume you want a star that's relatively friendly to life as we know it. So a white dwarf that got thrown to the galactic rim in the aftermath of the supernova of its former partner is  probably not what you want. Similarly, a red giant system may be undesirable, since it'd be pretty hard to survive your sun going red giant.  
> **username_0**: @PM2Ring If a star is undergoing fusion, doesn't it have SOME Goldilocks  temperature zone between 5C and 30C relatively friendly to life? For a captured planet, a relocated planet, or some other artificial construct like a giant space station orbiting in the zone? I think it just needs to be a source of radiative power; for perhaps an intentionally remote research station (for security and safety purposes while developing a new technology).  
> **username_5**: Oh, ok. Still, a red giant system isn't a fun place to live. Their output can be quite variable, and they can spew out an awful lot of dust. But I guess if you can't migrate to another system you have to make do with what you've got.  
> **username_0**: @barrycarter That one (CX330) is pretty interesting. I presume if it could form, so could a sun-like star, with planets...  
> **username_6**: @barrycarter What is the uncertainty in the distance compared to the average spacing between stars?  

---

## 2 answers

### Answer by username_7 on 2018-10-11. Score: 1 | Accepted answer

From a comment by [barrycarter](https://astronomy.stackexchange.com/users/21/barrycarter):

> In our galaxy, it might be [CX330](https://www.jpl.nasa.gov/news/news.php?feature=6578), which is 1000 light years from any star-forming region, much less any star. However, the article describes it as "Loneliest Young Star", so there may be older stars that are even more isolated. [This source](https://www.smh.com.au/technology/cx330-galaxys-loneliest-baby-star-discovered-wandering-far-from-stellar-nurseries-20160728-gqfg1i.html) contains the phrase "CX330 [...] has been described as the galaxy's loneliest star.", but this may just be bad reporting.


---

### Answer by username_8 on 2018-09-11. Score: 0

I don't think anyone knows the answer to this! People have only recently started looking at the Gaia catalogues and they contain so much data that most of it won't get looked at unless it is in an interesting area. Astronomers have started combing through the data seeing what we can find in our favourite regions but most people focus on the more densely populated areas (clusters and places where stars are forming) rather than the mainly empty areas (probably older stars not interacting with each other).

So I think this is something you could find in the catalogue, the information does exist, but no one is particularly interested in spending a lot of time looking for it because we won't learn much from those regions.

> **Comments:**
> **username_9**: One would not "look" for it, but rather write a program to sift through the data to find the star furthest away. That is in itself a fun programming problem since the catalogue is so large that it is hard to keep it all in memory at the same time for a normal PC: some cleverness is needed to handle the search problem.  

---

