Epic variable star 50 EP

HD 4004

RA 10.8683° · Dec 64.7598° · star

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Score breakdown

· 5 badges

50 pts · Epic

Epic 78 pts → Anomaly

Wolf-Rayet star (shedding itself) +34
Variable star +5
Never sets (northern circumpolar) +4
Gently variable +4
A named variable star +3

Total score 50

28 more points to reach Anomaly.

Badges

Variable star · +5
Never sets (northern circumpolar) · +4
Wolf-Rayet star (shedding itself) · +34
Gently variable · +4
A named variable star · +3

Trivia

Hard to believe

True brightness. It pours out about 772.7 thousand 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 WN5 — 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 10.1 you'll want a small backyard telescope, over in Cassiopeia.
Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
Best time of year. It stands highest in the middle of the night around October — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out yellow-white (B−V 0.4) — a shade brighter and crisper than our own Sun.
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: -9.89
bv: 0.401
constellation: Cas
luminosity: 787045.7897
mag: 10.11
name: HD 4004
spect: WN5
var amplitude: 0.16
var designation: V863
var max: 9.998
var min: 10.158

Nearby objects

About HD 4004

HD 4004 is an epic variable star. It sits in the constellation Cas, shines at apparent magnitude 10.11 and has spectral type WN5.

Its spectrum reads WN5 — 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 4004 in the constellation Cas. At apparent magnitude 10.11, a small backyard telescope will bring it into view.

Like any astronomical target, HD 4004 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 4004 is an epic variable star

HD 4004 scores 50 points on Spacedle's rarity scale, which places it in the epic tier. Another 28 points would lift it into a rarer tier.

That score comes from 5 science badges — Variable star, Never sets (northern circumpolar), 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.