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Common variable star 21 EP

HD 232821

RA 55.4576° · Dec 53.2937° · star

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Score breakdown

· 5 badges
21 pts · Common
Common 22 pts → Uncommon
  • Variable star +5
  • White A-type star +5
  • Never sets (northern circumpolar) +4
  • Gently variable +4
  • A named variable star +3
Total score 21

1 more point to reach Uncommon.

Badges

  • Variable star · +5
  • Never sets (northern circumpolar) · +4
  • White A-type star · +5
  • Gently variable · +4
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 1.6 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 A0 — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.
  • 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 9.3 you'll want a small backyard telescope, over in Camelopardalis.
  • 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 November — 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 0.5) — 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
-10.66
bv
0.485
constellation
Cam
luminosity
1599558.0286
mag
9.34
name
HD 232821
spect
A0
var amplitude
0.2
var designation
CV
var max
9.299
var min
9.499

About HD 232821

HD 232821 is a common variable star. It sits in the constellation Cam, shines at apparent magnitude 9.34 and has spectral type A0.

Its spectrum reads A0 — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

How to see it

Look for HD 232821 in the constellation Cam. At apparent magnitude 9.34, a small backyard telescope will bring it into view.

Like any astronomical target, HD 232821 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 232821 is a common variable star

HD 232821 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, Never sets (northern circumpolar), White A-type 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.