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Rare star 38 EP

HD 152246

RA 253.5221° · Dec -41.0795° · star

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Score breakdown

· 4 badges
38 pts · Rare
Rare 50 pts → Epic
  • Blazing O-type star +26
  • Giant star +6
  • Star +3
  • On the zodiac +3
Total score 38

12 more points to reach Epic.

Badges

  • Star · +3
  • On the zodiac · +3
  • Blazing O-type star · +26
  • Giant star · +6

Trivia

What it actually is

  • Spectral class. Its spectrum reads O9:III: — 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.

Find it in the sky

  • How to spot it. At magnitude 7.3 it is just past naked-eye reach — ordinary binoculars will pull it in, 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 brilliant white (B−V 0.1) — hotter and whiter than the Sun, the colour of Sirius or Vega.
  • 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 8700 K, against the Sun's 5778 K.

What's in a name

  • Its catalogue. The HD number is from the Henry Draper Catalogue, in which Annie Jump Cannon personally classified the spectra of nearly 400,000 stars — still the largest such feat by one person.

Properties

absmag
-12.68
bv
0.135
constellation
Sco
luminosity
10280162.9813
mag
7.32
name
HD 152246
spect
O9:III:

About HD 152246

HD 152246 is a rare star. It sits in the constellation Sco, shines at apparent magnitude 7.32 and has spectral type O9:III:.

Its spectrum reads O9:III: — 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 HD 152246 in the constellation Sco. At apparent magnitude 7.32, it is an easy target for binoculars.

Like any astronomical target, HD 152246 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 152246 is a rare star

HD 152246 scores 38 points on Spacedle's rarity scale, which places it in the rare tier. Another 12 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, On the zodiac, Blazing O-type star and Giant 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.