Rare variable star 38 EP

HD 229196

RA 305.7949° · Dec 40.8750° · star

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Score breakdown

· 4 badges

38 pts · Rare

Rare 50 pts → Epic

Blazing O-type star +26
Variable star +5
Gently variable +4
A named variable star +3

Total score 38

12 more points to reach Epic.

Badges

Variable star · +5
Blazing O-type star · +26
Gently variable · +4
A named variable star · +3

Trivia

Hard to believe

True brightness. It pours out about 3.4 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 O5 — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.
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 8.5 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 yellow (B−V 0.8) — almost exactly the Sun's own shade — a stellar twin in colour, if not in size.
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: -11.5
bv: 0.774
constellation: Cyg
luminosity: 3467368.5045
mag: 8.5
name: HD 229196
spect: O5
var amplitude: 0.07
var designation: V2245
var max: 8.466
var min: 8.536

Nearby objects

About HD 229196

HD 229196 is a rare variable star. It sits in the constellation Cyg, shines at apparent magnitude 8.5 and has spectral type O5.

Its spectrum reads O5 — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.

How to see it

Look for HD 229196 in the constellation Cyg. At apparent magnitude 8.5, it is an easy target for binoculars.

Like any astronomical target, HD 229196 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 229196 is a rare variable star

HD 229196 scores 38 points on Spacedle's rarity scale, which places it in the rare tier. Another 12 points would lift it into a rarer tier.

That score comes from 4 science badges — Variable star, Blazing O-type 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.