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Uncommon star 27 EP

HD 72800

RA 128.2241° · Dec -47.6055° · star

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Score breakdown

· 3 badges
27 pts · Uncommon
Uncommon 34 pts → Rare
  • Supergiant +18
  • Hot blue B-type star +6
  • Star +3
Total score 27

7 more points to reach Rare.

Badges

  • Star · +3
  • Hot blue B-type star · +6
  • Supergiant · +18

Trivia

What it actually is

  • Spectral class. Its spectrum reads B9Iab: — 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 supergiant. Drop it where the Sun is and its surface would engulf the inner planets.

Find it in the sky

  • How to spot it. At magnitude 6.6 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Vela.
  • 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 January — 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 8750 K, against the Sun's 5778 K.

Properties

absmag
-13.43
bv
0.13
constellation
Vel
luminosity
20511621.7883
mag
6.57
name
HD 72800
spect
B9Iab:

About HD 72800

HD 72800 is an uncommon star. It sits in the constellation Vel, shines at apparent magnitude 6.57 and has spectral type B9Iab:.

Its spectrum reads B9Iab: — 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 HD 72800 in the constellation Vel. At apparent magnitude 6.57, it is an easy target for binoculars.

Like any astronomical target, HD 72800 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 72800 is an uncommon star

HD 72800 scores 27 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 7 points would lift it into a rarer tier.

That score comes from 3 science badges — Star, Hot blue B-type star and Supergiant — 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.