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Uncommon star 22 EP

HD 209709

RA 331.2644° · Dec 14.8159° · star

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Score breakdown

· 4 badges
22 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • Giant star +6
  • Cool red M-type star +5
  • Star +3
Total score 22

12 more points to reach Rare.

Badges

  • Star · +3
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8

Trivia

What it actually is

  • Spectral class. Its spectrum reads M2.5III: — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.

Sense of scale

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 6.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Pegasus.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around August — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Getting there

  • Aboard Voyager 1. ≈ 9.5 million years at Voyager 1's speed (17 km/s).

Properties

absmag
0.285
bv
1.523
constellation
Peg
dist ly
539.9933
luminosity
66.9885
mag
6.38
name
HD 209709
spect
M2.5III:

About HD 209709

HD 209709 is an uncommon star. It lies about 540 light-years from Earth, sits in the constellation Peg, shines at apparent magnitude 6.38 and has spectral type M2.5III:.

Its spectrum reads M2.5III: — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HD 209709 in the constellation Peg. At apparent magnitude 6.38, it is an easy target for binoculars.

Like any astronomical target, HD 209709 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 209709 is an uncommon star

HD 209709 scores 22 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 12 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Cool red M-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.