← Back to dex
Epic variable star 52 EP

HD 223737

RA 358.0609° · Dec -15.8546° · star

Loading sky survey…
🌌 View in 3D star map
Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 7 badges
52 pts · Epic
Epic 78 pts → Anomaly
  • Supergiant +18
  • Strongly variable +10
  • Deep red star +8
  • Variable star +5
  • Cool red M-type star +5
  • On the zodiac +3
  • A named variable star +3
Total score 52

26 more points to reach Anomaly.

Badges

  • Variable star · +5
  • On the zodiac · +3
  • Cool red M-type star · +5
  • Supergiant · +18
  • Deep red star · +8
  • Strongly variable · +10
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 2.1 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 M1/M2Ib/II — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • 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 9.1 you'll want a small backyard telescope, over in Aquarius.
  • 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 September — 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.

Properties

absmag
-10.95
bv
1.48
constellation
Aqr
luminosity
2089296.1309
mag
9.05
name
HD 223737
spect
M1/M2Ib/II
var amplitude
1.47
var designation
Z
var max
8.391
var min
9.861

About HD 223737

HD 223737 is an epic variable star. It sits in the constellation Aqr, shines at apparent magnitude 9.05 and has spectral type M1/M2Ib/II.

Its spectrum reads M1/M2Ib/II — 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 223737 in the constellation Aqr. At apparent magnitude 9.05, a small backyard telescope will bring it into view.

Like any astronomical target, HD 223737 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 223737 is an epic variable star

HD 223737 scores 52 points on Spacedle's rarity scale, which places it in the epic tier. Another 26 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, On the zodiac, Cool red M-type star, Supergiant, Deep red star, Strongly 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.