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Uncommon variable star 23 EP

20 Cap

RA 314.9006° · Dec -19.0353° · star

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Score breakdown

· 6 badges
23 pts · Uncommon
Uncommon 34 pts → Rare
  • Variable star +5
  • White A-type star +5
  • Blue-white star +5
  • On the zodiac +3
  • A named variable star +3
  • Barely variable (under 0.05 mag) +2
Total score 23

11 more points to reach Rare.

Badges

  • Variable star · +5
  • On the zodiac · +3
  • White A-type star · +5
  • Blue-white star · +5
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads Ap Si — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.
  • 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 6.3 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Capricornus.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around August — that's when to go looking.

Could we get there?

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

Getting there

  • Aboard Voyager 1. ≈ 9.4 million years at Voyager 1's speed (17 km/s).

Properties

absmag
0.183
bv
-0.11
constellation
Cap
dist ly
535.5599
luminosity
73.5868
mag
6.26
name
20 Cap
spect
Ap Si
var amplitude
0.05
var designation
AO
var max
6.246
var min
6.296

About 20 Cap

20 Cap is an uncommon variable star. It lies about 535.6 light-years from Earth, sits in the constellation Cap, shines at apparent magnitude 6.26 and has spectral type Ap Si.

Its spectrum reads Ap Si — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

How to see it

Look for 20 Cap in the constellation Cap. At apparent magnitude 6.26, it is an easy target for binoculars.

Like any astronomical target, 20 Cap 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 20 Cap is an uncommon variable star

20 Cap scores 23 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 11 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, On the zodiac, White A-type star, Blue-white 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.