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Common star 20 EP

HD 37699

RA 85.0841° · Dec -2.4356° · star

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Score breakdown

· 4 badges
20 pts · Common
Common 22 pts → Uncommon
  • In Orion's hunting ground +6
  • Hot blue B-type star +6
  • Blue-white star +5
  • Star +3
Total score 20

2 more points to reach Uncommon.

Badges

  • Star · +3
  • In Orion's hunting ground · +6
  • Hot blue B-type star · +6
  • Blue-white star · +5

Trivia

What it actually is

  • Spectral class. Its spectrum reads B5 — 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 7.6 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Orion.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • 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 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 11870 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
-12.38
bv
-0.117
constellation
Ori
luminosity
7798301.1052
mag
7.62
name
HD 37699
spect
B5

Nearby objects

About HD 37699

HD 37699 is a common star. It sits in the constellation Ori, shines at apparent magnitude 7.62 and has spectral type B5.

Its spectrum reads B5 — 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 37699 in the constellation Ori. At apparent magnitude 7.62, it is an easy target for binoculars.

Like any astronomical target, HD 37699 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 37699 is a common star

HD 37699 scores 20 points on Spacedle's rarity scale, which places it in the common tier. Another 2 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, In Orion's hunting ground, Hot blue B-type 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.