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Rare star 35 EP

HD 213023

RA 336.7182° · Dec 63.7180° · star

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Score breakdown

· 4 badges
35 pts · Rare
Rare 50 pts → Epic
  • Blazing O-type star +26
  • Never sets (northern circumpolar) +4
  • Star +3
  • Main-sequence star +2
Total score 35

15 more points to reach Epic.

Badges

  • Star · +3
  • Never sets (northern circumpolar) · +4
  • Blazing O-type star · +26
  • Main-sequence star · +2

Trivia

Hard to believe

  • True brightness. It pours out about 3.5 million times as much light as the Sun. It only looks ordinary because it is so far away.

What it actually is

  • Spectral class. Its spectrum reads O9V: — 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.

Find it in the sky

  • How to spot it. At magnitude 8.5 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cepheus.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around August — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out yellow (B−V 0.7) — almost exactly the Sun's own shade — a stellar twin in colour, if not in size.
  • 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
-11.53
bv
0.749
constellation
Cep
luminosity
3564511.3343
mag
8.47
name
HD 213023
spect
O9V:

Nearby objects

About HD 213023

HD 213023 is a rare star. It sits in the constellation Cep, shines at apparent magnitude 8.47 and has spectral type O9V:.

Its spectrum reads O9V: — 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 213023 in the constellation Cep. At apparent magnitude 8.47, it is an easy target for binoculars.

Like any astronomical target, HD 213023 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 213023 is a rare star

HD 213023 scores 35 points on Spacedle's rarity scale, which places it in the rare tier. Another 15 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Never sets (northern circumpolar), Blazing O-type star and Main-sequence 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.