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Rare variable star 36 EP

HD 158243

RA 262.7797° · Dec -53.4787° · star

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Score breakdown

· 5 badges
36 pts · Rare
Rare 50 pts → Epic
  • Supergiant +18
  • Hot blue B-type star +6
  • Variable star +5
  • Gently variable +4
  • A named variable star +3
Total score 36

14 more points to reach Epic.

Badges

  • Variable star · +5
  • Hot blue B-type star · +6
  • Supergiant · +18
  • Gently variable · +4
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 4.7 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 B1Iab: — 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 supergiant. Drop it where the Sun is and its surface would engulf the inner planets.
  • 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 8.1 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Ara.
  • 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) — hotter and whiter than the Sun, the colour of Sirius or Vega.

Properties

absmag
-11.86
bv
0.003
constellation
Ara
luminosity
4830588.0204
mag
8.14
name
HD 158243
spect
B1Iab:
var amplitude
0.07
var designation
V861
var max
8.101
var min
8.171

About HD 158243

HD 158243 is a rare variable star. It sits in the constellation Ara, shines at apparent magnitude 8.14 and has spectral type B1Iab:.

Its spectrum reads B1Iab: — 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 158243 in the constellation Ara. At apparent magnitude 8.14, it is an easy target for binoculars.

Like any astronomical target, HD 158243 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 158243 is a rare variable star

HD 158243 scores 36 points on Spacedle's rarity scale, which places it in the rare tier. Another 14 points would lift it into a rarer tier.

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