Rare variable star 46 EP

HD 191765

RA 302.5591° · Dec 36.1764° · star

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Score breakdown

· 4 badges

46 pts · Rare

Rare 50 pts → Epic

Wolf-Rayet star (shedding itself) +34
Variable star +5
Gently variable +4
A named variable star +3

Total score 46

4 more points to reach Epic.

Badges

Variable star · +5
Wolf-Rayet star (shedding itself) · +34
Gently variable · +4
A named variable star · +3

Trivia

Hard to believe

True brightness. It pours out about 5.1 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 WN6 (SB1) — a Wolf-Rayet star: a stellar monster shedding its own outer layers in a ferocious wind, on its way to a supernova.
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 8.1 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 brilliant white (B−V 0) — hotter and whiter than the Sun, the colour of Sirius or Vega.
Why no green stars. No star ever looks green: a surface hot enough to peak in green also floods out plenty of red and blue, and your eye blends the mixture back to white.

Properties

absmag: -11.93
bv: 0.033
constellation: Cyg
luminosity: 5152286.4458
mag: 8.07
name: HD 191765
spect: WN6 (SB1)
var amplitude: 0.07
var designation: V1769
var max: 8.037
var min: 8.107

Nearby objects

About HD 191765

HD 191765 is a rare variable star. It sits in the constellation Cyg, shines at apparent magnitude 8.07 and has spectral type WN6 (SB1).

Its spectrum reads WN6 (SB1) — a Wolf-Rayet star: a stellar monster shedding its own outer layers in a ferocious wind, on its way to a supernova.

How to see it

Look for HD 191765 in the constellation Cyg. At apparent magnitude 8.07, it is an easy target for binoculars.

Like any astronomical target, HD 191765 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 191765 is a rare variable star

HD 191765 scores 46 points on Spacedle's rarity scale, which places it in the rare tier. Another 4 points would lift it into a rarer tier.

That score comes from 4 science badges — Variable star, Wolf-Rayet star (shedding itself), 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.