Rare variable star 36 EP

HD 166734

RA 273.1027° · Dec -10.7314° · star

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Score breakdown

· 4 badges

36 pts · Rare

Rare 50 pts → Epic

Blazing O-type star +26
Variable star +5
A named variable star +3
Barely variable (under 0.05 mag) +2

Total score 36

14 more points to reach Epic.

Badges

Variable star · +5
Blazing O-type star · +26
Barely variable (under 0.05 mag) · +2
A named variable star · +3

Trivia

Hard to believe

True brightness. It pours out about 3.7 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 O8e — 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 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Serpens.
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 June — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out orange (B−V 0.9) — cooler than the Sun, and the kind of star that burns steadily for tens of billions of years.
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: -11.59
bv: 0.881
constellation: Ser
luminosity: 3767037.9898
mag: 8.41
name: HD 166734
spect: O8e
var amplitude: 0.05
var designation: V411
var max: 8.393
var min: 8.443

Nearby objects

About HD 166734

HD 166734 is a rare variable star. It sits in the constellation Ser, shines at apparent magnitude 8.41 and has spectral type O8e.

Its spectrum reads O8e — 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 166734 in the constellation Ser. At apparent magnitude 8.41, it is an easy target for binoculars.

Like any astronomical target, HD 166734 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 166734 is a rare variable star

HD 166734 scores 36 points on Spacedle's rarity scale, which places it in the rare tier. Another 14 points would lift it into a rarer tier.

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