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Common star 21 EP

HD 147040

RA 245.6052° · Dec -56.4234° · star

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Score breakdown

· 4 badges
21 pts · Common
Common 22 pts → Uncommon
  • Deep red star +8
  • Cool red M-type star +5
  • Subgiant (leaving the main sequence) +5
  • Star +3
Total score 21

1 more point to reach Uncommon.

Badges

  • Star · +3
  • Cool red M-type star · +5
  • Subgiant (leaving the main sequence) · +5
  • Deep red star · +8

Trivia

Hard to believe

  • True brightness. It pours out about 4.6 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 M0IV — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • 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.

Find it in the sky

  • How to spot it. At magnitude 8.2 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Norma.
  • 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 May — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out deep orange-red (B−V 1.9) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3300 K, against the Sun's 5778 K.

Properties

absmag
-11.83
bv
1.879
constellation
Nor
luminosity
4698941.0861
mag
8.17
name
HD 147040
spect
M0IV

About HD 147040

HD 147040 is a common star. It sits in the constellation Nor, shines at apparent magnitude 8.17 and has spectral type M0IV.

Its spectrum reads M0IV — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HD 147040 in the constellation Nor. At apparent magnitude 8.17, it is an easy target for binoculars.

Like any astronomical target, HD 147040 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 147040 is a common star

HD 147040 scores 21 points on Spacedle's rarity scale, which places it in the common tier. Another 1 point would lift it into a rarer tier.

That score comes from 4 science badges — Star, Cool red M-type star, Subgiant (leaving the main sequence) and Deep red 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.