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Rare variable star 41 EP

70 Oph

RA 271.3637° · Dec 2.5001° · star

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Score breakdown

· 8 badges
41 pts · Rare
Rare 50 pts → Epic
  • Nearby (<25 ly) +12
  • Naked-eye visible +8
  • Binary star +6
  • Variable star +5
  • Orange K-type star +3
  • A named variable star +3
  • Main-sequence star +2
  • Barely variable (under 0.05 mag) +2
Total score 41

9 more points to reach Epic.

Badges

  • Variable star · +5
  • Nearby (<25 ly) · +12
  • Naked-eye visible · +8
  • Binary star · +6
  • Orange K-type star · +3
  • Main-sequence star · +2
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What makes it special

  • Not one star but two. It is a binary: two stars orbiting a shared centre of mass. More than half of all the 'stars' you can see are actually multiple systems.

What it actually is

  • Spectral class. Its spectrum reads K0V SB — 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 on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.
  • 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. Inside our stellar backyard: every radio broadcast humanity has ever made has already swept past it.

Find it in the sky

  • How to spot it. At magnitude 4 you can see it with your own eyes from a dark site, over in Ophiuchus.
  • 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 June — that's when to go looking.

Properties

absmag
5.499
binary
yes
bv
0.86
constellation
Oph
dist ly
16.5798
luminosity
0.55
mag
4.03
name
70 Oph
spect
K0V SB
var amplitude
0.03
var designation
V2391
var max
4.02
var min
4.05

About 70 Oph

70 Oph is a rare variable star. It lies about 16.6 light-years from Earth, sits in the constellation Oph, shines at apparent magnitude 4.03 and has spectral type K0V SB.

It is a binary: two stars orbiting a shared centre of mass. More than half of all the 'stars' you can see are actually multiple systems.

How to see it

Look for 70 Oph in the constellation Oph. At apparent magnitude 4.03, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 70 Oph 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 70 Oph is a rare variable star

70 Oph scores 41 points on Spacedle's rarity scale, which places it in the rare tier. Another 9 points would lift it into a rarer tier.

That score comes from 8 science badges — Variable star, Nearby (<25 ly), Naked-eye visible, Binary star, Orange K-type star, Main-sequence star, Barely variable (under 0.05 mag) 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.