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Common star 15 EP

HD 40427

RA 89.8438° · Dec 13.7353° · star

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Score breakdown

· 3 badges
15 pts · Common
Common 22 pts → Uncommon
  • In Orion's hunting ground +6
  • Hot blue B-type star +6
  • Star +3
Total score 15

7 more points to reach Uncommon.

Badges

  • Star · +3
  • In Orion's hunting ground · +6
  • Hot blue B-type star · +6

Trivia

Hard to believe

  • True brightness. It pours out about 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 B9 — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

Find it in the sky

  • How to spot it. At magnitude 8.1 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Orion.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around December — 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) — 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.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 9880 K, against the Sun's 5778 K.

Properties

absmag
-11.91
bv
0.02
constellation
Ori
luminosity
5058246.62
mag
8.09
name
HD 40427
spect
B9

About HD 40427

HD 40427 is a common star. It sits in the constellation Ori, shines at apparent magnitude 8.09 and has spectral type B9.

Its spectrum reads B9 — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 40427 in the constellation Ori. At apparent magnitude 8.09, it is an easy target for binoculars.

Like any astronomical target, HD 40427 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 40427 is a common star

HD 40427 scores 15 points on Spacedle's rarity scale, which places it in the common tier. Another 7 points would lift it into a rarer tier.

That score comes from 3 science badges — Star, In Orion's hunting ground and Hot blue B-type 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.