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Uncommon star 28 EP

HD 107424

RA 185.2959° · Dec -56.7740° · star

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Score breakdown

· 5 badges
28 pts · Uncommon
Uncommon 34 pts → Rare
  • Under the Southern Cross +8
  • Hot blue B-type star +6
  • Giant star +6
  • Blue-white star +5
  • Star +3
Total score 28

6 more points to reach Rare.

Badges

  • Star · +3
  • Under the Southern Cross · +8
  • Hot blue B-type star · +6
  • Giant star · +6
  • Blue-white star · +5

Trivia

What it actually is

  • Spectral class. Its spectrum reads B8/B9III — 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 7.8 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Crux.
  • 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 March — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out blue-white (B−V -0) — the hallmark of a surface far hotter than the Sun's.
  • 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 10250 K, against the Sun's 5778 K.

What's in a name

  • Its catalogue. The HD number is from the Henry Draper Catalogue, in which Annie Jump Cannon personally classified the spectra of nearly 400,000 stars — still the largest such feat by one person.

Properties

absmag
-12.25
bv
-0.01
constellation
Cru
luminosity
6918309.7092
mag
7.75
name
HD 107424
spect
B8/B9III

About HD 107424

HD 107424 is an uncommon star. It sits in the constellation Cru, shines at apparent magnitude 7.75 and has spectral type B8/B9III.

Its spectrum reads B8/B9III — 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 107424 in the constellation Cru. At apparent magnitude 7.75, it is an easy target for binoculars.

Like any astronomical target, HD 107424 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 107424 is an uncommon star

HD 107424 scores 28 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 6 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, Under the Southern Cross, Hot blue B-type star, Giant star and Blue-white 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.