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Uncommon variable star 27 EP

HR 6747

RA 271.1557° · Dec 1.9190° · star

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Score breakdown

· 6 badges
27 pts · Uncommon
Uncommon 34 pts → Rare
  • Hot blue B-type star +6
  • Giant star +6
  • Variable star +5
  • Blue-white star +5
  • A named variable star +3
  • Barely variable (under 0.05 mag) +2
Total score 27

7 more points to reach Rare.

Badges

  • Variable star · +5
  • Hot blue B-type star · +6
  • Giant star · +6
  • Blue-white star · +5
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads B0IIIn — 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 6.1 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Ophiuchus.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • 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 blue-white (B−V -0.1) — the hallmark of a surface far hotter than the Sun's.
  • 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
-13.86
bv
-0.056
constellation
Oph
luminosity
30478949.8963
mag
6.14
name
HR 6747
spect
B0IIIn
var amplitude
0.03
var designation
V986
var max
6.131
var min
6.161

Nearby objects

About HR 6747

HR 6747 is an uncommon variable star. It sits in the constellation Oph, shines at apparent magnitude 6.14 and has spectral type B0IIIn.

Its spectrum reads B0IIIn — 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 HR 6747 in the constellation Oph. At apparent magnitude 6.14, it is an easy target for binoculars.

Like any astronomical target, HR 6747 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 HR 6747 is an uncommon variable star

HR 6747 scores 27 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 7 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Hot blue B-type star, Giant star, Blue-white star, Barely variable (under 0.05 mag) 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.