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Rare variable star 47 EP

HD 202380

RA 318.1969° · Dec 60.0980° · star

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Score breakdown

· 7 badges
47 pts · Rare
Rare 50 pts → Epic
  • Supergiant +18
  • Deep red star +8
  • Variable star +5
  • Cool red M-type star +5
  • Never sets (northern circumpolar) +4
  • Gently variable +4
  • A named variable star +3
Total score 47

3 more points to reach Epic.

Badges

  • Variable star · +5
  • Never sets (northern circumpolar) · +4
  • Cool red M-type star · +5
  • Supergiant · +18
  • Deep red star · +8
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads M3Ib — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • Where it is in life. It is a supergiant, hundreds of times wider than the Sun.
  • 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 6.9 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cepheus.
  • 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 August — 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 2.3) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 2880 K, against the Sun's 5778 K.

Properties

absmag
-13.09
bv
2.306
constellation
Cep
luminosity
14996848.355
mag
6.91
name
HD 202380
spect
M3Ib
var amplitude
0.26
var designation
V419
var max
6.785
var min
7.045

About HD 202380

HD 202380 is a rare variable star. It sits in the constellation Cep, shines at apparent magnitude 6.91 and has spectral type M3Ib.

Its spectrum reads M3Ib — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HD 202380 in the constellation Cep. At apparent magnitude 6.91, it is an easy target for binoculars.

Like any astronomical target, HD 202380 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 202380 is a rare variable star

HD 202380 scores 47 points on Spacedle's rarity scale, which places it in the rare tier. Another 3 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Never sets (northern circumpolar), Cool red M-type star, Supergiant, Deep red 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.