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Uncommon star 22 EP

HD 19399

RA 45.9022° · Dec -65.5285° · star

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Score breakdown

· 4 badges
22 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • Giant star +6
  • Cool red M-type star +5
  • Star +3
Total score 22

12 more points to reach Rare.

Badges

  • Star · +3
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8

Trivia

Hard to believe

  • True brightness. It pours out about 5 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 M4III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.

Find it in the sky

  • How to spot it. At magnitude 8.1 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Horologium.
  • 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 November — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out deep orange-red (B−V 1.5) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3790 K, against the Sun's 5778 K.

Properties

absmag
-11.92
bv
1.501
constellation
Hor
luminosity
5105049.9998
mag
8.08
name
HD 19399
spect
M4III

About HD 19399

HD 19399 is an uncommon star. It sits in the constellation Hor, shines at apparent magnitude 8.08 and has spectral type M4III.

Its spectrum reads M4III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HD 19399 in the constellation Hor. At apparent magnitude 8.08, it is an easy target for binoculars.

Like any astronomical target, HD 19399 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 19399 is an uncommon star

HD 19399 scores 22 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 12 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Cool red M-type star, Giant star and Deep red 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.