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Common star 20 EP

HD 138699

RA 234.8196° · Dec -72.8656° · star

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Score breakdown

· 4 badges
20 pts · Common
Common 22 pts → Uncommon
  • Deep red star +8
  • Giant star +6
  • Star +3
  • Orange K-type star +3
Total score 20

2 more points to reach Uncommon.

Badges

  • Star · +3
  • Orange K-type star · +3
  • Giant star · +6
  • Deep red star · +8

Trivia

Hard to believe

  • True brightness. It pours out about 2.9 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 K4III — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.
  • 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 8.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Apus.
  • 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 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 1.5) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3790 K, against the Sun's 5778 K.

Properties

absmag
-11.31
bv
1.504
constellation
Aps
luminosity
2910717.1181
mag
8.69
name
HD 138699
spect
K4III

About HD 138699

HD 138699 is a common star. It sits in the constellation Aps, shines at apparent magnitude 8.69 and has spectral type K4III.

Its spectrum reads K4III — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

How to see it

Look for HD 138699 in the constellation Aps. At apparent magnitude 8.69, it is an easy target for binoculars.

Like any astronomical target, HD 138699 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 138699 is a common star

HD 138699 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, Orange K-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.