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Rare star 47 EP

HD 120521

RA 207.8916° · Dec -58.5395° · star

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Score breakdown

· 3 badges
47 pts · Rare
Rare 50 pts → Epic
  • Blazing O-type star +26
  • Supergiant +18
  • Star +3
Total score 47

3 more points to reach Epic.

Badges

  • Star · +3
  • Blazing O-type star · +26
  • Supergiant · +18

Trivia

Hard to believe

  • True brightness. It pours out about 3.2 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 O9Ib — 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 supergiant, hundreds of times wider than the Sun.

Find it in the sky

  • How to spot it. At magnitude 8.6 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Centaurus.
  • 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 April — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out brilliant white (B−V 0.2) — hotter and whiter than the Sun, the colour of Sirius or Vega.
  • 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
-11.44
bv
0.231
constellation
Cen
luminosity
3280952.9311
mag
8.56
name
HD 120521
spect
O9Ib

About HD 120521

HD 120521 is a rare star. It sits in the constellation Cen, shines at apparent magnitude 8.56 and has spectral type O9Ib.

Its spectrum reads O9Ib — 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 120521 in the constellation Cen. At apparent magnitude 8.56, it is an easy target for binoculars.

Like any astronomical target, HD 120521 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 120521 is a rare star

HD 120521 scores 47 points on Spacedle's rarity scale, which places it in the rare tier. Another 3 points would lift it into a rarer tier.

That score comes from 3 science badges — Star, Blazing O-type star and Supergiant — 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.