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Uncommon star 22 EP

HD 105381

RA 182.0034° · Dec -44.8195° · 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 5.1 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 M2III: — 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 Centaurus.
  • 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 March — 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 1.6) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3660 K, against the Sun's 5778 K.

Properties

absmag
-11.94
bv
1.591
constellation
Cen
luminosity
5199959.9653
mag
8.06
name
HD 105381
spect
M2III:

About HD 105381

HD 105381 is an uncommon star. It sits in the constellation Cen, shines at apparent magnitude 8.06 and has spectral type M2III:.

Its spectrum reads M2III: — 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 105381 in the constellation Cen. At apparent magnitude 8.06, it is an easy target for binoculars.

Like any astronomical target, HD 105381 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 105381 is an uncommon star

HD 105381 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.