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Uncommon variable star 30 EP

HD 163726

RA 269.8346° · Dec -37.8813° · star

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Score breakdown

· 5 badges
30 pts · Uncommon
Uncommon 34 pts → Rare
  • Strongly variable +10
  • Hot blue B-type star +6
  • Giant star +6
  • Variable star +5
  • A named variable star +3
Total score 30

4 more points to reach Rare.

Badges

  • Variable star · +5
  • Hot blue B-type star · +6
  • Giant star · +6
  • Strongly variable · +10
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 1.5 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 B9III — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
  • Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.
  • 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 9.4 you'll want a small backyard telescope, over in Corona Australis.
  • 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 June — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out brilliant white (B−V 0.1) — hotter and whiter than the Sun, the colour of Sirius or Vega.

Properties

absmag
-10.58
bv
0.096
constellation
CrA
luminosity
1485935.6423
mag
9.42
name
HD 163726
spect
B9III
var amplitude
0.83
var designation
RW
var max
9.369
var min
10.199

About HD 163726

HD 163726 is an uncommon variable star. It sits in the constellation CrA, shines at apparent magnitude 9.42 and has spectral type B9III.

Its spectrum reads B9III — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 163726 in the constellation CrA. At apparent magnitude 9.42, a small backyard telescope will bring it into view.

Like any astronomical target, HD 163726 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 163726 is an uncommon variable star

HD 163726 scores 30 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 4 points would lift it into a rarer tier.

That score comes from 5 science badges — Variable star, Hot blue B-type star, Giant 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.