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Rare star 35 EP

HD 305560

RA 161.6186° · Dec -60.5641° · star

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Score breakdown

· 3 badges
35 pts · Rare
Rare 50 pts → Epic
  • Blazing O-type star +26
  • Giant star +6
  • Star +3
Total score 35

15 more points to reach Epic.

Badges

  • Star · +3
  • Blazing O-type star · +26
  • Giant star · +6

Trivia

Hard to believe

  • True brightness. It pours out about 1.1 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 O9.5III — 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 giant. It has already exhausted its core hydrogen and swollen up enormously in response.

Find it in the sky

  • How to spot it. At magnitude 9.8 you'll want a small backyard telescope, over in Carina.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • Best time of year. It stands highest in the middle of the night around March — 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 0.3) — 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
-10.24
bv
0.344
constellation
Car
luminosity
1086425.6236
mag
9.76
name
HD 305560
spect
O9.5III

About HD 305560

HD 305560 is a rare star. It sits in the constellation Car, shines at apparent magnitude 9.76 and has spectral type O9.5III.

Its spectrum reads O9.5III — 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 305560 in the constellation Car. At apparent magnitude 9.76, a small backyard telescope will bring it into view.

Like any astronomical target, HD 305560 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 305560 is a rare star

HD 305560 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 3 science badges — Star, Blazing O-type star and Giant 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.