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Trash star 10 EP

HD 139969

RA 236.1645° · Dec -62.5137° · star

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Score breakdown

· 3 badges
10 pts · Trash
Trash 15 pts → Common
  • White A-type star +5
  • Star +3
  • Main-sequence star +2
Total score 10

5 more points to reach Common.

Badges

  • Star · +3
  • White A-type star · +5
  • Main-sequence star · +2

Trivia

Hard to believe

  • True brightness. It pours out about 1 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 A3V — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.
  • Where it is in life. It is on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.

Find it in the sky

  • How to spot it. At magnitude 9.8 you'll want a small backyard telescope, over in Triangulum Australe.
  • 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 brilliant white (B−V 0.2) — hotter and whiter than the Sun, the colour of Sirius or Vega.
  • 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.

Properties

absmag
-10.17
bv
0.197
constellation
TrA
luminosity
1018591.3881
mag
9.83
name
HD 139969
spect
A3V

About HD 139969

HD 139969 is a trash star. It sits in the constellation TrA, shines at apparent magnitude 9.83 and has spectral type A3V.

Its spectrum reads A3V — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

How to see it

Look for HD 139969 in the constellation TrA. At apparent magnitude 9.83, a small backyard telescope will bring it into view.

Like any astronomical target, HD 139969 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 139969 is a trash star

HD 139969 scores 10 points on Spacedle's rarity scale, which places it in the trash tier. Another 5 points would lift it into a rarer tier.

That score comes from 3 science badges — Star, White A-type star and Main-sequence 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.