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Uncommon star 33 EP

HD 188339

RA 299.0441° · Dec -38.3265° · star

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Score breakdown

· 6 badges
33 pts · Uncommon
Uncommon 34 pts → Rare
  • Toward the galactic centre +8
  • Deep red star +8
  • Giant star +6
  • Cool red M-type star +5
  • Star +3
  • On the zodiac +3
Total score 33

1 more point to reach Rare.

Badges

  • Star · +3
  • Toward the galactic centre · +8
  • On the zodiac · +3
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8

Trivia

What it actually is

  • Spectral class. Its spectrum reads M1III — 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 giant. It has already exhausted its core hydrogen and swollen up enormously in response.

Find it in the sky

  • How to spot it. At magnitude 6.6 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Sagittarius.
  • 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 July — 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 1.7) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3510 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
-13.38
bv
1.705
constellation
Sgr
luminosity
19588446.7351
mag
6.62
name
HD 188339
spect
M1III

About HD 188339

HD 188339 is an uncommon star. It sits in the constellation Sgr, shines at apparent magnitude 6.62 and has spectral type M1III.

Its spectrum reads M1III — 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 188339 in the constellation Sgr. At apparent magnitude 6.62, it is an easy target for binoculars.

Like any astronomical target, HD 188339 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 188339 is an uncommon star

HD 188339 scores 33 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 1 point would lift it into a rarer tier.

That score comes from 6 science badges — Star, Toward the galactic centre, On the zodiac, Cool red M-type star, Giant star 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.