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Uncommon variable star 32 EP

18Tau Per

RA 43.5644° · Dec 52.7625° · star

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Score breakdown

· 6 badges
32 pts · Uncommon
Uncommon 34 pts → Rare
  • Naked-eye visible +8
  • Sun-like G-type star +8
  • Giant star +6
  • Variable star +5
  • A named variable star +3
  • Barely variable (under 0.05 mag) +2
Total score 32

2 more points to reach Rare.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Sun-like G-type star · +8
  • Giant star · +6
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads G4III... — a G-type star: the very same spectral class as our own Sun.
  • Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.
  • 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. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 3.9 you can see it with your own eyes from a dark site, over in Perseus.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around November — that's when to go looking.

Could we get there?

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

Properties

absmag
-0.529
bv
0.758
constellation
Per
dist ly
254.2135
luminosity
141.7751
mag
3.93
name
18Tau Per
spect
G4III...
var amplitude
0.02
var designation
Tau
var max
3.925
var min
3.945

About 18Tau Per

18Tau Per is an uncommon variable star. It lies about 254.2 light-years from Earth, sits in the constellation Per, shines at apparent magnitude 3.93 and has spectral type G4III....

Its spectrum reads G4III... — a G-type star: the very same spectral class as our own Sun.

How to see it

Look for 18Tau Per in the constellation Per. At apparent magnitude 3.93, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 18Tau Per 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 18Tau Per is an uncommon variable star

18Tau Per scores 32 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 2 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Naked-eye visible, Sun-like G-type star, Giant 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.