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Uncommon star 29 EP

13Sig2UMa

RA 137.5981° · Dec 67.1340° · star

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Score breakdown

· 6 badges
29 pts · Uncommon
Uncommon 34 pts → Rare
  • Naked-eye visible +8
  • Binary star +6
  • Subgiant (leaving the main sequence) +5
  • Never sets (northern circumpolar) +4
  • Star +3
  • Yellow-white F-type star +3
Total score 29

5 more points to reach Rare.

Badges

  • Star · +3
  • Naked-eye visible · +8
  • Binary star · +6
  • Never sets (northern circumpolar) · +4
  • Yellow-white F-type star · +3
  • Subgiant (leaving the main sequence) · +5

Trivia

What makes it special

  • Not one star but two. It is a binary: two stars orbiting a shared centre of mass. More than half of all the 'stars' you can see are actually multiple systems.

What it actually is

  • Spectral class. Its spectrum reads F7IV-V — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
  • Where it is in life. It is a subgiant, caught in the act of leaving the main sequence as the hydrogen in its core runs out.

Sense of scale

  • In perspective. Inside our stellar backyard: every radio broadcast humanity has ever made has already swept past it.

Find it in the sky

  • How to spot it. At magnitude 4.8 you can see it with your own eyes from a dark site, over in Ursa Major.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around February — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Properties

absmag
3.254
binary
yes
bv
0.489
constellation
UMa
dist ly
66.4677
luminosity
4.3491
mag
4.8
name
13Sig2UMa
spect
F7IV-V

About 13Sig2UMa

13Sig2UMa is an uncommon star. It lies about 66.5 light-years from Earth, sits in the constellation UMa, shines at apparent magnitude 4.8 and has spectral type F7IV-V.

It is a binary: two stars orbiting a shared centre of mass. More than half of all the 'stars' you can see are actually multiple systems.

How to see it

Look for 13Sig2UMa in the constellation UMa. At apparent magnitude 4.8, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 13Sig2UMa is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.

Why 13Sig2UMa is an uncommon star

13Sig2UMa scores 29 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 5 points would lift it into a rarer tier.

That score comes from 6 science badges — Star, Naked-eye visible, Binary star, Never sets (northern circumpolar), Yellow-white F-type star and Subgiant (leaving the main sequence) — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.