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Uncommon variable star 28 EP

HIP 117576

RA 357.6647° · Dec 60.9109° · star

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Score breakdown

· 6 badges
28 pts · Uncommon
Uncommon 34 pts → Rare
  • Hot blue B-type star +6
  • Giant star +6
  • Variable star +5
  • Never sets (northern circumpolar) +4
  • Gently variable +4
  • A named variable star +3
Total score 28

6 more points to reach Rare.

Badges

  • Variable star · +5
  • Never sets (northern circumpolar) · +4
  • Hot blue B-type star · +6
  • Giant star · +6
  • Gently variable · +4
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 1.1 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 B0.5III — 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 9.8 you'll want a small backyard telescope, over in Cassiopeia.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around September — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out yellow (B−V 0.6) — almost exactly the Sun's own shade — a stellar twin in colour, if not in size.

Properties

absmag
-10.24
bv
0.629
constellation
Cas
luminosity
1086425.6236
mag
9.76
name
HIP 117576
spect
B0.5III
var amplitude
0.36
var designation
UU
var max
9.617
var min
9.977

About HIP 117576

HIP 117576 is an uncommon variable star. It sits in the constellation Cas, shines at apparent magnitude 9.76 and has spectral type B0.5III.

Its spectrum reads B0.5III — 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 HIP 117576 in the constellation Cas. At apparent magnitude 9.76, a small backyard telescope will bring it into view.

Like any astronomical target, HIP 117576 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 HIP 117576 is an uncommon variable star

HIP 117576 scores 28 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 6 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Never sets (northern circumpolar), Hot blue B-type star, Giant 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.