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Common star 19 EP

HD 47139

RA 99.0851° · Dec -19.4921° · star

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Score breakdown

· 4 badges
19 pts · Common
Common 22 pts → Uncommon
  • Hot blue B-type star +6
  • Subgiant (leaving the main sequence) +5
  • Blue-white star +5
  • Star +3
Total score 19

3 more points to reach Uncommon.

Badges

  • Star · +3
  • Hot blue B-type star · +6
  • Subgiant (leaving the main sequence) · +5
  • Blue-white star · +5

Trivia

What it actually is

  • Spectral class. Its spectrum reads B9IV/V — 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 subgiant, caught in the act of leaving the main sequence as the hydrogen in its core runs out.

Sense of scale

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 7.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Canis Major.
  • 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 December — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Getting there

  • Aboard Voyager 1. ≈ 8 million years at Voyager 1's speed (17 km/s).

Properties

absmag
1.697
bv
-0.022
constellation
CMa
dist ly
452.9945
luminosity
18.2474
mag
7.41
name
HD 47139
spect
B9IV/V

About HD 47139

HD 47139 is a common star. It lies about 453 light-years from Earth, sits in the constellation CMa, shines at apparent magnitude 7.41 and has spectral type B9IV/V.

Its spectrum reads B9IV/V — 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 47139 in the constellation CMa. At apparent magnitude 7.41, it is an easy target for binoculars.

Like any astronomical target, HD 47139 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 47139 is a common star

HD 47139 scores 19 points on Spacedle's rarity scale, which places it in the common tier. Another 3 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Hot blue B-type star, Subgiant (leaving the main sequence) 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.