The empire of Beta Canum Venaticorum

I’ve already written up astronomer Margaret Turnbull’s top five choices for stars that could have Earthlike planets.  They are:

• Beta Canum Venaticorum, a G0V star 27 light years away.  It may have a binary companion.  Also known as Gliese 475.
• HD 10307, a G1V star with an M companion, 41 light years away, in the constellation Andromeda.  Also known as Gliese 67.
• HD 211415, a G1V star with an M companion at a safe distance, 44 light years away in the constellation Grus.  Also known as Gliese 853.
• 18 Scorpii, a G1V star 46 light years away.  May have a binary companion.  Also known as Gliese 616.
• 51 Pegasi, a G2V star 50 light years away.  Has a super-Jovian planet, the first ever detected by astronomers back in 1995.  Also known as Gliese 882.

Over the next few days, I’ll be doing what I just did for Sol -- looking at the area that lies within 10 light years of each, and doing a chart that shows how far the stars in that sphere are from each other.  Note that this will include all stars I can find out about, regardless of their suitability for harbouring life-bearing planets.  Presumably when the aliens who live around one of these capital stars start their interstellar explorations, they’ll want to find out about everything that’s out there…

Also note that given the trend of recent discoveries in the 15 light years or so around Sol, there are undoubtedly M and even K dwarf stars that don’t appear on these charts because they haven’t been discovered yet.

Anyway, here are the stars within 10 light years of Beta Canum Venaticorum (distances are from that star):

• Gliese 450: 5.0 light-years, class M1V
• CF Ursae Majoris/Gliese 451: 5.0 light-years, class G8VI
• 61 Ursae Majoris/Gliese 434: 7.5 light-years, class G8V
• DG Canum Venaticorum/GJ 3789: 7.7 light-years, class M4V or VI
• Beta Comae Berenices/Gliese 502: 8.1 light-years, class G0V
• Gliese 508: 8.5 light-years, class M1.5V

And here’s the chart:

	450	451	434	3789	502	508
475	5.0	5.0	7.4	7.6	8.1	8.5
450		2.3	3.4	10.2	9.6	12.5
451			2.6	11.0	10.0	11.1
434				12.5	10.9	13.1
3789					4.1	12.1
502						11.7

Note that although this sphere is 20 light years across, no two stars in it are farther apart than 13 light years.  That’s because the stars are not evenly distributed throughout the sphere; most have a lower Y coordinate and a higher Z coordinate than the central star (meaning they’re ahead of it in the galactic rotation, and to its galactic north).