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Rare variable star 49 EP

47 Eri

RA 68.5485° · Dec -8.2314° · star

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Score breakdown

· 8 badges
49 pts · Rare
Rare 50 pts → Epic
  • Intrinsically luminous (Mv < −2) +10
  • Naked-eye visible +8
  • Deep red star +8
  • Giant star +6
  • Variable star +5
  • Cool red M-type star +5
  • Gently variable +4
  • A named variable star +3
Total score 49

1 more point to reach Epic.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8
  • Intrinsically luminous (Mv < −2) · +10
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads M3III — 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.
  • 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 5.2 you can see it with your own eyes from a dark site, over in Eridanus.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around November — that's when to go looking.

Could we get there?

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

Properties

absmag
-2.221
bv
1.708
constellation
Eri
dist ly
994.3779
luminosity
673.5968
mag
5.2
name
47 Eri
spect
M3III
var amplitude
0.09
var designation
DV
var max
5.147
var min
5.237

About 47 Eri

47 Eri is a rare variable star. It lies about 994.4 light-years from Earth, sits in the constellation Eri, shines at apparent magnitude 5.2 and has spectral type M3III.

Its spectrum reads M3III — 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 47 Eri in the constellation Eri. At apparent magnitude 5.2, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 47 Eri 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 47 Eri is a rare variable star

47 Eri scores 49 points on Spacedle's rarity scale, which places it in the rare tier. Another 1 point would lift it into a rarer tier.

That score comes from 8 science badges — Variable star, Naked-eye visible, Cool red M-type star, Giant star, Deep red star, Intrinsically luminous (Mv < −2), 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.