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Uncommon variable star 29 EP

13 Cet

RA 8.8120° · Dec -3.5928° · star

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Score breakdown

· 7 badges
29 pts · Uncommon
Uncommon 34 pts → Rare
  • Naked-eye visible +8
  • Binary star +6
  • Variable star +5
  • Yellow-white F-type star +3
  • A named variable star +3
  • Main-sequence star +2
  • Barely variable (under 0.05 mag) +2
Total score 29

5 more points to reach Rare.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Binary star · +6
  • Yellow-white F-type star · +3
  • Main-sequence star · +2
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

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 F8V... — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
  • Where it is in life. It is on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.
  • It changes. This star does not hold still: its brightness rises and falls on a rhythm of hours, days or years, either pulsing in size or being eclipsed by a companion.

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 5.2 you can see it with your own eyes from a dark site, over in Cetus.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around September — that's when to go looking.

Properties

absmag
3.563
binary
yes
bv
0.567
constellation
Cet
dist ly
69.3212
luminosity
3.2719
mag
5.2
name
13 Cet
spect
F8V...
var amplitude
0.02
var designation
BU
var max
5.19
var min
5.21

About 13 Cet

13 Cet is an uncommon variable star. It lies about 69.3 light-years from Earth, sits in the constellation Cet, shines at apparent magnitude 5.2 and has spectral type F8V....

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 13 Cet in the constellation Cet. At apparent magnitude 5.2, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 13 Cet 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 13 Cet is an uncommon variable star

13 Cet 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 7 science badges — Variable star, Naked-eye visible, Binary star, Yellow-white F-type star, Main-sequence star, Barely variable (under 0.05 mag) and A named variable star — 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.