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Rare variable star 37 EP

20 Eri

RA 54.0726° · Dec -17.4671° · star

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Score breakdown

· 7 badges
37 pts · Rare
Rare 50 pts → Epic
  • Naked-eye visible +8
  • Hot blue B-type star +6
  • Giant star +6
  • Variable star +5
  • Blue-white star +5
  • Gently variable +4
  • A named variable star +3
Total score 37

13 more points to reach Epic.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Hot blue B-type star · +6
  • Giant star · +6
  • Blue-white star · +5
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads B8/B9III — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
  • 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.
  • 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.

Could we get there?

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

Getting there

  • Aboard Voyager 1. ≈ 8.6 million years at Voyager 1's speed (17 km/s).

Properties

absmag
-0.63
bv
-0.117
constellation
Eri
dist ly
486.7999
luminosity
155.5966
mag
5.24
name
20 Eri
spect
B8/B9III
var amplitude
0.06
var designation
EG
var max
5.202
var min
5.262

About 20 Eri

20 Eri is a rare variable star. It lies about 486.8 light-years from Earth, sits in the constellation Eri, shines at apparent magnitude 5.24 and has spectral type B8/B9III.

Its spectrum reads B8/B9III — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for 20 Eri in the constellation Eri. At apparent magnitude 5.24, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 20 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 20 Eri is a rare variable star

20 Eri scores 37 points on Spacedle's rarity scale, which places it in the rare tier. Another 13 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Naked-eye visible, Hot blue B-type star, Giant star, Blue-white 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.