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Trash star 14 EP

HD 171256

RA 278.9767° · Dec -44.4291° · star

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Score breakdown

· 3 badges
14 pts · Trash
Trash 15 pts → Common
  • Hot blue B-type star +6
  • Subgiant (leaving the main sequence) +5
  • Star +3
Total score 14

1 more point to reach Common.

Badges

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

Trivia

Hard to believe

  • True brightness. It pours out about 1.6 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 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.

Find it in the sky

  • How to spot it. At magnitude 9.3 you'll want a small backyard telescope, over in Corona Australis.
  • 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 June — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out yellow (B−V 0.7) — almost exactly the Sun's own shade — a stellar twin in colour, if not in size.
  • 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
-10.68
bv
0.665
constellation
CrA
luminosity
1629296.0326
mag
9.32
name
HD 171256
spect
B9IV/V

Nearby objects

About HD 171256

HD 171256 is a trash star. It sits in the constellation CrA, shines at apparent magnitude 9.32 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 171256 in the constellation CrA. At apparent magnitude 9.32, a small backyard telescope will bring it into view.

Like any astronomical target, HD 171256 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 171256 is a trash star

HD 171256 scores 14 points on Spacedle's rarity scale, which places it in the trash tier. Another 1 point would lift it into a rarer tier.

That score comes from 3 science badges — Star, Hot blue B-type star and Subgiant (leaving the main sequence) — 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.