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Rare variable star 43 EP

HD 131217

RA 223.7373° · Dec -61.0758° · star

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Score breakdown

· 7 badges
43 pts · Rare
Rare 50 pts → Epic
  • Bright giant +12
  • Deep red star +8
  • Distant (over 1,000 light-years) +6
  • Variable star +5
  • Cool red M-type star +5
  • Gently variable +4
  • A named variable star +3
Total score 43

7 more points to reach Epic.

Badges

  • Variable star · +5
  • Distant (over 1,000 light-years) · +6
  • Cool red M-type star · +5
  • Bright giant · +12
  • Deep red star · +8
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads M2/M3II — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • It changes. This star does not hold still: its brightness rises and falls on a rhythm of hours, days or years, either pulsing in size or being eclipsed by a companion.

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 7.5 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Circinus.
  • 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.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Getting there

  • Aboard Voyager 1. ≈ 18 million years at Voyager 1's speed (17 km/s).

Properties

absmag
-0.031
bv
1.74
constellation
Cir
dist ly
1022.4325
luminosity
89.619
mag
7.45
name
HD 131217
spect
M2/M3II
var amplitude
0.12
var designation
CR
var max
7.405
var min
7.525

About HD 131217

HD 131217 is a rare variable star. It lies about 1,022.4 light-years from Earth, sits in the constellation Cir, shines at apparent magnitude 7.45 and has spectral type M2/M3II.

Its spectrum reads M2/M3II — 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 131217 in the constellation Cir. At apparent magnitude 7.45, it is an easy target for binoculars.

Like any astronomical target, HD 131217 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 131217 is a rare variable star

HD 131217 scores 43 points on Spacedle's rarity scale, which places it in the rare tier. Another 7 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Distant (over 1,000 light-years), Cool red M-type star, Bright giant, Deep red star, Gently variable and A named variable 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.