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Epic variable star 59 EP

HD 163181

RA 269.0670° · Dec -32.4750° · star

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Score breakdown

· 6 badges
59 pts · Epic
Epic 78 pts → Anomaly
  • Blazing O-type star +26
  • Supergiant +18
  • Variable star +5
  • Gently variable +4
  • On the zodiac +3
  • A named variable star +3
Total score 59

19 more points to reach Anomaly.

Badges

  • Variable star · +5
  • On the zodiac · +3
  • Blazing O-type star · +26
  • Supergiant · +18
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads O9.5Ia/ab — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.
  • Where it is in life. It is a luminous supergiant — among the largest and rarest stars in the galaxy.
  • 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.

Find it in the sky

  • How to spot it. At magnitude 6.6 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Scorpius.
  • 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 June — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out yellow-white (B−V 0.4) — a shade brighter and crisper than our own Sun.
  • Why no green stars. No star ever looks green: a surface hot enough to peak in green also floods out plenty of red and blue, and your eye blends the mixture back to white.

Properties

absmag
-13.41
bv
0.422
constellation
Sco
luminosity
20137242.4986
mag
6.59
name
HD 163181
spect
O9.5Ia/ab
var amplitude
0.39
var designation
V453
var max
6.383
var min
6.773

About HD 163181

HD 163181 is an epic variable star. It sits in the constellation Sco, shines at apparent magnitude 6.59 and has spectral type O9.5Ia/ab.

Its spectrum reads O9.5Ia/ab — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.

How to see it

Look for HD 163181 in the constellation Sco. At apparent magnitude 6.59, it is an easy target for binoculars.

Like any astronomical target, HD 163181 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 HD 163181 is an epic variable star

HD 163181 scores 59 points on Spacedle's rarity scale, which places it in the epic tier. Another 19 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, On the zodiac, Blazing O-type star, Supergiant, Gently variable 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.