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Epic variable star 56 EP

13Zet Oph

RA 249.2897° · Dec -10.5671° · star

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Score breakdown

· 7 badges
56 pts · Epic
Epic 78 pts → Anomaly
  • Blazing O-type star +26
  • Intrinsically luminous (Mv < −2) +10
  • Naked-eye visible +8
  • Variable star +5
  • A named variable star +3
  • Main-sequence star +2
  • Barely variable (under 0.05 mag) +2
Total score 56

22 more points to reach Anomaly.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Blazing O-type star · +26
  • Main-sequence star · +2
  • Intrinsically luminous (Mv < −2) · +10
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads O9.5V — 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 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. 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 2.5 you can see it with your own eyes from a dark site, over in Ophiuchus.
  • 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 May — that's when to go looking.

Could we get there?

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

Properties

absmag
-2.711
bv
0.038
constellation
Oph
dist ly
366.056
luminosity
1057.7913
mag
2.54
name
13Zet Oph
spect
O9.5V
var amplitude
0.03
var designation
Zet
var max
2.52
var min
2.55

About 13Zet Oph

13Zet Oph is an epic variable star. It lies about 366.1 light-years from Earth, sits in the constellation Oph, shines at apparent magnitude 2.54 and has spectral type O9.5V.

Its spectrum reads O9.5V — 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 13Zet Oph in the constellation Oph. At apparent magnitude 2.54, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 13Zet Oph 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 13Zet Oph is an epic variable star

13Zet Oph scores 56 points on Spacedle's rarity scale, which places it in the epic tier. Another 22 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Naked-eye visible, Blazing O-type star, Main-sequence star, Intrinsically luminous (Mv < −2), 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.