Uncommon variable star 27 EP

HD 149881

RA 249.2425° · Dec 14.4753° · star

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Score breakdown

· 6 badges

27 pts · Uncommon

Uncommon 34 pts → Rare

Hot blue B-type star +6
Giant star +6
Variable star +5
Blue-white star +5
A named variable star +3
Barely variable (under 0.05 mag) +2

Total score 27

7 more points to reach Rare.

Badges

Variable star · +5
Hot blue B-type star · +6
Giant star · +6
Blue-white star · +5
Barely variable (under 0.05 mag) · +2
A named variable star · +3

Trivia

What it actually is

Spectral class. Its spectrum reads B0.5III — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.
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 7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Hercules.
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 May — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out blue-white (B−V -0.2) — the hallmark of a surface far hotter than the Sun's.
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: -12.96
bv: -0.174
constellation: Her
luminosity: 13304544.1798
mag: 7.04
name: HD 149881
spect: B0.5III
var amplitude: 0.03
var designation: V600
var max: 7.024
var min: 7.054

Nearby objects

About HD 149881

HD 149881 is an uncommon variable star. It sits in the constellation Her, shines at apparent magnitude 7.04 and has spectral type B0.5III.

Its spectrum reads B0.5III — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 149881 in the constellation Her. At apparent magnitude 7.04, it is an easy target for binoculars.

Like any astronomical target, HD 149881 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 149881 is an uncommon variable star

HD 149881 scores 27 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 7 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Hot blue B-type star, Giant star, Blue-white 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.