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Uncommon star 32 EP

HD 29138

RA 63.4447° · Dec -84.4858° · star

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Score breakdown

· 4 badges
32 pts · Uncommon
Uncommon 34 pts → Rare
  • Supergiant +18
  • Hot blue B-type star +6
  • Blue-white star +5
  • Star +3
Total score 32

2 more points to reach Rare.

Badges

  • Star · +3
  • Hot blue B-type star · +6
  • Supergiant · +18
  • Blue-white star · +5

Trivia

What it actually is

  • Spectral class. Its spectrum reads B1Iab: — 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.
  • Where it is in life. It is a supergiant. Drop it where the Sun is and its surface would engulf the inner planets.

Find it in the sky

  • How to spot it. At magnitude 7.2 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Mensa.
  • 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 November — 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 -0.1) — 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 11470 K, against the Sun's 5778 K.

Properties

absmag
-12.8
bv
-0.094
constellation
Men
luminosity
11481536.215
mag
7.2
name
HD 29138
spect
B1Iab:

About HD 29138

HD 29138 is an uncommon star. It sits in the constellation Men, shines at apparent magnitude 7.2 and has spectral type B1Iab:.

Its spectrum reads B1Iab: — 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 29138 in the constellation Men. At apparent magnitude 7.2, it is an easy target for binoculars.

Like any astronomical target, HD 29138 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 29138 is an uncommon star

HD 29138 scores 32 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 2 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Hot blue B-type star, Supergiant 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.