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Rare star 39 EP

HD 161807

RA 267.3531° · Dec -38.9838° · star

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Score breakdown

· 5 badges
39 pts · Rare
Rare 50 pts → Epic
  • Blazing O-type star +26
  • Blue-white star +5
  • Star +3
  • On the zodiac +3
  • Main-sequence star +2
Total score 39

11 more points to reach Epic.

Badges

  • Star · +3
  • On the zodiac · +3
  • Blazing O-type star · +26
  • Main-sequence star · +2
  • Blue-white star · +5

Trivia

What it actually is

  • Spectral class. Its spectrum reads O9.5V:n... — 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.
  • Where it is in life. It is on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.

Find it in the sky

  • How to spot it. At magnitude 7 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 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 11200 K, against the Sun's 5778 K.

Properties

absmag
-12.99
bv
-0.077
constellation
Sco
luminosity
13677288.256
mag
7.01
name
HD 161807
spect
O9.5V:n...

About HD 161807

HD 161807 is a rare star. It sits in the constellation Sco, shines at apparent magnitude 7.01 and has spectral type O9.5V:n....

Its spectrum reads O9.5V:n... — 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 161807 in the constellation Sco. At apparent magnitude 7.01, it is an easy target for binoculars.

Like any astronomical target, HD 161807 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 161807 is a rare star

HD 161807 scores 39 points on Spacedle's rarity scale, which places it in the rare tier. Another 11 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, On the zodiac, Blazing O-type star, Main-sequence star and Blue-white 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.