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Epic variable star 54 EP

HR 6397

RA 258.8302° · Dec -33.5484° · star

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Score breakdown

· 7 badges
54 pts · Epic
Epic 78 pts → Anomaly
  • Blazing O-type star +26
  • Naked-eye visible +8
  • Variable star +5
  • Blue-white star +5
  • Gently variable +4
  • On the zodiac +3
  • A named variable star +3
Total score 54

24 more points to reach Anomaly.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • On the zodiac · +3
  • Blazing O-type star · +26
  • Blue-white star · +5
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads O9 — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.
  • 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 5.6 you can see it with your own eyes from a dark site, over in Scorpius.
  • 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 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.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 10880 K, against the Sun's 5778 K.

Properties

absmag
-14.4
bv
-0.056
constellation
Sco
luminosity
50118723.3627
mag
5.6
name
HR 6397
spect
O9
var amplitude
0.07
var designation
V1075
var max
5.582
var min
5.652

About HR 6397

HR 6397 is an epic variable star. It sits in the constellation Sco, shines at apparent magnitude 5.6 and has spectral type O9.

Its spectrum reads O9 — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.

How to see it

Look for HR 6397 in the constellation Sco. At apparent magnitude 5.6, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HR 6397 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 6397 is an epic variable star

HR 6397 scores 54 points on Spacedle's rarity scale, which places it in the epic tier. Another 24 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Naked-eye visible, On the zodiac, Blazing O-type star, Blue-white 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.