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Uncommon variable star 33 EP

HD 117399

RA 202.8892° · Dec -61.5824° · star

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Score breakdown

· 5 badges
33 pts · Uncommon
Uncommon 34 pts → Rare
  • Supergiant +18
  • Variable star +5
  • Gently variable +4
  • Yellow-white F-type star +3
  • A named variable star +3
Total score 33

1 more point to reach Rare.

Badges

  • Variable star · +5
  • Yellow-white F-type star · +3
  • Supergiant · +18
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads F6/F7Ib — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
  • 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 6.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Centaurus.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • Best time of year. It stands highest in the middle of the night around April — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out yellow (B−V 0.8) — almost exactly the Sun's own shade — a stellar twin in colour, if not in size.
  • 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 5350 K, against the Sun's 5778 K.

Properties

absmag
-13.34
bv
0.777
constellation
Cen
luminosity
18879913.491
mag
6.66
name
HD 117399
spect
F6/F7Ib
var amplitude
0.27
var designation
V659
var max
6.457
var min
6.727

Nearby objects

About HD 117399

HD 117399 is an uncommon variable star. It sits in the constellation Cen, shines at apparent magnitude 6.66 and has spectral type F6/F7Ib.

Its spectrum reads F6/F7Ib — an F-type star — a little hotter, whiter and shorter-lived than the Sun.

How to see it

Look for HD 117399 in the constellation Cen. At apparent magnitude 6.66, it is an easy target for binoculars.

Like any astronomical target, HD 117399 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 117399 is an uncommon variable star

HD 117399 scores 33 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 1 point would lift it into a rarer tier.

That score comes from 5 science badges — Variable star, Yellow-white F-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.