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Epic variable star 51 EP

HD 186686

RA 295.9074° · Dec 48.7782° · star

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Score breakdown

· 5 badges
51 pts · Epic
Epic 78 pts → Anomaly
  • Dramatic variable (over 2 magnitudes) +20
  • Supergiant +18
  • Variable star +5
  • Cool red M-type star +5
  • A named variable star +3
Total score 51

27 more points to reach Anomaly.

Badges

  • Variable star · +5
  • Cool red M-type star · +5
  • Supergiant · +18
  • Dramatic variable (over 2 magnitudes) · +20
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 3.6 million times as much light as the Sun. It only looks ordinary because it is so far away.

What it actually is

  • Spectral class. Its spectrum reads M2e-M8.8Ibe — 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.

Find it in the sky

  • How to spot it. At magnitude 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cygnus.
  • 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 July — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out orange (B−V 1.3) — cooler than the Sun, and the kind of star that burns steadily for tens of billions of years.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 4180 K, against the Sun's 5778 K.

Properties

absmag
-11.56
bv
1.27
constellation
Cyg
luminosity
3664375.7465
mag
8.44
name
HD 186686
spect
M2e-M8.8Ibe
var amplitude
4.18
var designation
RT
var max
6.543
var min
10.723

Nearby objects

About HD 186686

HD 186686 is an epic variable star. It sits in the constellation Cyg, shines at apparent magnitude 8.44 and has spectral type M2e-M8.8Ibe.

Its spectrum reads M2e-M8.8Ibe — 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 186686 in the constellation Cyg. At apparent magnitude 8.44, it is an easy target for binoculars.

Like any astronomical target, HD 186686 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 186686 is an epic variable star

HD 186686 scores 51 points on Spacedle's rarity scale, which places it in the epic tier. Another 27 points would lift it into a rarer tier.

That score comes from 5 science badges — Variable star, Cool red M-type star, Supergiant, Dramatic variable (over 2 magnitudes) 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.