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Trash star 12 EP

HD 21371

RA 51.5319° · Dec -22.1609° · star

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Score breakdown

· 3 badges
12 pts · Trash
Trash 15 pts → Common
  • Giant star +6
  • Star +3
  • Orange K-type star +3
Total score 12

3 more points to reach Common.

Badges

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

Trivia

Hard to believe

  • True brightness. It pours out about 2 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 K2III — 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 9.1 you'll want a small backyard telescope, over in Eridanus.
  • 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 November — 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
-10.91
bv
0.69
constellation
Eri
luminosity
2013724.2499
mag
9.09
name
HD 21371
spect
K2III

Nearby objects

About HD 21371

HD 21371 is a trash star. It sits in the constellation Eri, shines at apparent magnitude 9.09 and has spectral type K2III.

Its spectrum reads K2III — 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 21371 in the constellation Eri. At apparent magnitude 9.09, a small backyard telescope will bring it into view.

Like any astronomical target, HD 21371 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 21371 is a trash star

HD 21371 scores 12 points on Spacedle's rarity scale, which places it in the trash tier. Another 3 points would lift it into a rarer tier.

That score comes from 3 science badges — Star, Orange K-type star and Giant 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.