Common variable star 21 EP

HD 183909

RA 292.6491° · Dec 31.9801° · star

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Score breakdown

· 5 badges

21 pts · Common

Common 22 pts → Uncommon

Deep red star +8
Variable star +5
Orange K-type star +3
A named variable star +3
Barely variable (under 0.05 mag) +2

Total score 21

1 more point to reach Uncommon.

Badges

Variable star · +5
Orange K-type star · +3
Deep red star · +8
Barely variable (under 0.05 mag) · +2
A named variable star · +3

Trivia

What it actually is

Spectral class. Its spectrum reads K2 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.
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 7.5 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 deep orange-red (B−V 1.5) — one of the coolest surfaces a star can have while still fusing.

By the numbers

Surface temperature. Its colour puts the surface at roughly 3820 K, against the Sun's 5778 K.

What's in a name

Its catalogue. The HD number is from the Henry Draper Catalogue, in which Annie Jump Cannon personally classified the spectra of nearly 400,000 stars — still the largest such feat by one person.

Properties

absmag: -12.46
bv: 1.48
constellation: Cyg
luminosity: 8394599.8652
mag: 7.54
name: HD 183909
spect: K2
var amplitude: 0.05
var designation: V2286
var max: 7.525
var min: 7.575

Nearby objects

About HD 183909

HD 183909 is a common variable star. It sits in the constellation Cyg, shines at apparent magnitude 7.54 and has spectral type K2.

Its spectrum reads K2 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

How to see it

Look for HD 183909 in the constellation Cyg. At apparent magnitude 7.54, it is an easy target for binoculars.

Like any astronomical target, HD 183909 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 183909 is a common variable star

HD 183909 scores 21 points on Spacedle's rarity scale, which places it in the common tier. Another 1 point would lift it into a rarer tier.

That score comes from 5 science badges — Variable star, Orange K-type star, Deep red 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.