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Uncommon star 23 EP

HD 217022

RA 344.4306° · Dec -14.4484° · star

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Score breakdown

· 5 badges
23 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • Giant star +6
  • Star +3
  • On the zodiac +3
  • Orange K-type star +3
Total score 23

11 more points to reach Rare.

Badges

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

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 K3III — 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 Aquarius.
  • 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 September — 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 1.6) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3690 K, against the Sun's 5778 K.

Properties

absmag
-10.94
bv
1.574
constellation
Aqr
luminosity
2070141.3488
mag
9.06
name
HD 217022
spect
K3III

About HD 217022

HD 217022 is an uncommon star. It sits in the constellation Aqr, shines at apparent magnitude 9.06 and has spectral type K3III.

Its spectrum reads K3III — 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 217022 in the constellation Aqr. At apparent magnitude 9.06, a small backyard telescope will bring it into view.

Like any astronomical target, HD 217022 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 217022 is an uncommon star

HD 217022 scores 23 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 11 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, On the zodiac, 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.