Clusters of Nearby Stars

When it comes to science fiction, and locations near Earth (and the Solar System, henceforth referred to as Sol), the bulk of it, especially the less rigorous type, often ignores everything unless it has a prominent name. I guess this is a pretty common sort of thing in most any set of facts, but as a person who looks up and reads stuff, I cannot help but be aware that Star Trek: TOS has planets and civilizations based around short-lived stars deemed unsuitable for life as we know it, just because they have names, while thousands of other stars are ignored.

It is perhaps for this reason that I have a certain liking for stellar cartography, and for fictional settings that pay close attention to it. The main one that comes to my attention right now is 2300ad, an RPG which is somewhat out of date in term of starmaps now, but which had the benefit of more or less forcing people to pay attention to the hundreds of dimmer star systems out there, if only as waypoints. After all, just because a star is a red dwarf, does that mean it should be ignored, that it is not really a destination? This is the sort of thing that causes Sci-Fi to ignore just how big space is, and how many stars are in a galaxy (Stargate, I'm looking at you!).

To explore nearby space, including many red and white dwarfs, I've compiled together this set of star maps of my own, based on how I slice things up. Of course, many other people do the same (see Project Rho for an entire website of this), but I have to admit that most of the maps I have found seem unsatisfying to me. They have a tendency to use unfamiliar catalog names, to try and cram too much into a single map or too little. CHview, a nice, simple program for showing 3d starcharts, seemed better to me, but unless you keep the view radius low, the view simply becomes too cluttered too see things.

So below are the charts, compiled using data from RECONS, NStars, Solstation, the ISDB, and ARCINS.

  • The Sol Cluster
  • The Tau Ceti / Delta Pavonis Cluster
  • The Inner Red Dwarf Cloud
  • The Sirius / Procyon Cluster
  • The 82 Eridani Cluster
  • The Fomalhaut Cluster
  • The Gliese 570 Finger
  • The Wolf 630 Link
  • The 41 Arae Cluster
  • The Orion Cloud
  • The Gamma-Delta-Kappa Link
  • The Delta Trianguli Group
  • The Xi Boötis Finger
  • Alpha Mensae Finger
  • The 5 Suns Cluster
  • The 61 Cygni Cluster & Cassiopeae Triangle
  • Draconis Cluster
  • The Vega Cluster
  • 12 Ophiuchi Cluster & Rasalhague Cluster

  • A note on the images

    These images are produced using the old version of CHView, which I generally prefer over newer programs due to straightforward simplicity. The particular viewpoint used is entirely arbitrary; I simply rotated the view around until things seemed more or less clear to me, so for route planning, just use the links and not any sort of position. Some images use the chview grid, others do not.

    For links, 3 lengths are used: a 7.71 ly length (solid blue), more or less corresponding to the 2300ad stutterwarp limit, a 7.8 ly length (dashed blue), which is needed to reach Wolf 359 from Sol, and a 9.35 ly length (dashed maroon/brown), corresponding to the so-called Eber Stutterwarp from 2300ad.

    The Clusters/Clouds/Triangles, etc, are produced by just looking at what I get in CHview and dividing things up in my head. Sometimes this can be pretty difficult, but in most cases, it is not.

    However, a strong note of caution here: the positions of many stars are not very well pinned down. Sometimes the errors can be huge, and for a set of relationships that relies upon precise distances, this can be fatal. To show this in the images, some symbols are attached after the names for many (most, actually) systems to show uncertainty. So to explain: A single ? after the sytem name + starcount indicates the distance to Sol may be as much as half a light year off, based on parallax error. If there is more than 1 ?, the parallax error is even higher. A ~ after a name indicates there is no Hipparcos catalog ID I could find. Hipparcos was a space telescope launched by the ESA to determine the distances to as many stars as possible, and generally prooduced results that are considered much more accurate than earlier ground based effors.

    Even worse, there are many dim stars for which no position has ever been measured. Hipparcos did not really try to measure the parallaxes for dim stars, probably due to lack of sensetivity. Thus, even after Hipparcos, astronomers continue to 'discover' stars that are fairly close to Sol, by measuring the parallaxes of stars that had not been checked before. Examples include Teegarden's Star, and LHS 1723. RECONS, a group of astronomers who apparently lead the effort to better map nearby stars, feel that there are still many (hundreds, even) of stars within 10 parsecs waiting to be discovered. If the grandiose claims made of GAIA, the sucessor of Hipparcos are to believed, then this will be fixed in a few years.

    NEWS: February 26, 2017. The first data release of GAIA has been out for a few months now. This early release uses data from Hipparcos as well as GAIA to produce improved parallaxes for 2 million stars of intermediate brightness. I have not yet had the opportunity to produce a proper update to this page, but I have produced an updated version of my list of Nearby Stars, as well as the program I used to maintain it, NStars.

    Home sweet home, and one of the few areas of near space where two sunlike stars not in the same system are close to each other. Another peculiarity is that Proxima Centauri is probably close to the record for 'star furthest away from the centre of its system', at least is near space. It shows up as getting separate links in the chart. Only two links, disreagrding ones more than 7.8 ly, lead away from Sol.

    This big, big cluster contains many of the nearby stars that people actually hear about, like Tau Ceti and Espilon Eridani. The G-type stars, Tau Ceti and Delta Pavonis, I'm sure you can pick out. The K-type stars are Epsilon Eridani, Epsilon Indi (notable for being orbited by a Brown Dwarf binary), Gl 33, and J. Herschel 5173 A. I believe it forms the heart of the Chinese Arm in 2300ad.

    In comparison with the previous cluster, this group seems boring, a diffuse set of red, while, and brown dwarfs. However, it is one of only two groups that link directly to the Sol Cluster, and serves as a stepping stone to many other groups.

    The Tau Ceti / Delta Pavonis cluster, and the Inner Red Dwarf Cloud, are pretty much at opoosite ends of each other. Linking the two, you have two smaller clusters that do not link to the Sol Cluster...

    Notable mainly for it's bright, famous members, Sirius and Procyon, this cluster also contains the triple system Omicron 2 Eridani, or Keid, which is considered by many to be the home system of the Vulcans of Star Trek.

    82 Eridani... what is is good for? Well, other than being a sunlike star, the only mention of it I can find in fiction is that is 2300ad, it is regarded as the Eber homeworld (though not the original one).

    Outwards from Delta Pavonis...

    There are many fingers, clusters, and links leading out from the Tau Ceti / Delta Pavonis cluster. Let's start with the biggest...

    Long and loose, this cluster does not have much to recommend it to lovers of sunlike stars. It does have A-type stars like Fomalhaut and Deneb Algedi (also known as Delta Capricorni), but the Flare Star TW Piscis Austrini is the only firm K-type star in this grouping.

    Gliese 570! It's so cute! Err.. its a quadruple system with a K-type dwarf, 2 red dwarfs, and a brown dwarf, and is considered sunlike enough to be a target for NASA's TPF.

    This grouping is abit more interesting, tying as it does 4 other groups together. Some of it's systems are interesting too. 36 Ophiuchi is a triple star system with three K-type dwarfs. Wolf 630 is a quintuple star system once thought to have has a brown dwarf as well.

    41 Arae A is one of those nearby sunlike stars that you never hear about, but at least is also contains a K-type star as well. MLO 4 is another interesting system, with 2 K-type stars.

    Outwards from Sirius...

    There isn't all that much leading out from the Sirius / Procyon cluster at first, but it does get more interesting later on...

    The Orion cloud is kind of vague, but it does have some fine stars: Pi 3 Orionis, Chi 1 Orionis, and the dimmer K-systems, Gliese 250 and Gliese 204 (out on a long finger: I couldn't think of anywhere else to put that than the Orion Cloud).

    This paricular grouping is named after the three most important systems; Gamma Leporis, Delta Eridani (also known as Rana, an orange subgiant), and Kappa Ceti (known to produce superflares). Other notable stars are the 'solar analogue' 58 Eridani, and the K-type dwarf Gliese 183.

    The Delta Trianguli Group

    This outlying group has a number of systems, of which the most important is the close binary Delta Trianguli, and 2 other systems with K-type stars: 107 Piscium and the triple star system Gliese 105. You might also notice a finger sticking out... it leads to some stars of dubious validity, and I thought that this finger does not really deserve a separate identity.

    After a 'Star-Desert of Red Dwarfs'...

    Leading out from the Inner Red Dwarf Cloud (the somewhat poetic term above is taken from a Pyramind GURPS article), you find a number of F/G class systems. One is promising above the others, but I'll save that one for last.

    This finger can be generally said to be a long outcropping of red and white dwarfs, except for the Xi Boötis system, a K and G binary.

    Almost as long and narrow as they come, this link nonetheless seems pretty secure; the parallax errors are low.

    This has got to be a record folks: five more or less G-class stars (one is verging on F-class), in a single fairly small cluster. The Alula Australis system, the gateway, has two of them. Groombridge 1830 is a rare G-type subdwarf. 61 Ursae majoris is a cool young G system. And Beta Canum Venaticorum, also known as Chara, has been identified as one of the most likely to hold life as we know it.

    61 Cygni and Friends

    In 2300ad, the 61 Cygni Cluster is presented as a mysterious set of stars, unreachable by the ordinary stutterwarp and beyond the touch of man. However, well before 2300, improved star parallaxes and catalogs have shown that these stars are not so isolated...

    61 Cygni is a binary star system that has appeared alot in fiction. It contains two K-type dwarfs. The rest of the cluster is kind of boring, but the attached Cassiopeiae Triangle has 2 G-type Stars and 2 K-type in it's 3 systems. Eta Cassiopeiae is another G-K binary in the Alpha Centauri mold, whereas Mu Cassiopeiae is a G-type subdwarf with a red subdwarf is a fairly close orbit. Gliese 892 is a fairly bright K-type star.

    This system weighs in with Sigma Draconis and the binary Chi Draconis. For the latter, unfortunatly, the stars orbit too close to each other to permit a stable orbit in the habitable zone.

    Blue Giants

    Two finals images to round things off..

    Despite being fairly big, this cluster contains very little in the way of sunlike stars, having a single G-type in Mu Herculis. Vega is a pretty notable star however, and the Vega Cluster serves as a gateway for further groups containing sunlike stars.

    Perhaps clusters with Blue Stars naturally suffer from a defecit of K and G dwarfs : while the Rasalhague cluster has none, the 12 Ophiuchi Cluster, which links it to the Wolf 630 Link, has 3. 12 Ophiuchi itself is a rather bright K-dwarf (K0)

    Copyright© John Q. Metro, June 2008. All rights reserved.