← Back to dex
Uncommon star 28 EP

HD 39732

RA 88.5937° · Dec -1.0765° · star

Loading sky survey…
🌌 View in 3D star map
Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 5 badges
28 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • In Orion's hunting ground +6
  • Giant star +6
  • Cool red M-type star +5
  • Star +3
Total score 28

6 more points to reach Rare.

Badges

  • Star · +3
  • In Orion's hunting ground · +6
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8

Trivia

What it actually is

  • Spectral class. Its spectrum reads M3III — 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 7.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Orion.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around December — 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 1.8) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3440 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
-12.57
bv
1.758
constellation
Ori
luminosity
9289663.8678
mag
7.43
name
HD 39732
spect
M3III

About HD 39732

HD 39732 is an uncommon star. It sits in the constellation Ori, shines at apparent magnitude 7.43 and has spectral type M3III.

Its spectrum reads M3III — 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 39732 in the constellation Ori. At apparent magnitude 7.43, it is an easy target for binoculars.

Like any astronomical target, HD 39732 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 39732 is an uncommon star

HD 39732 scores 28 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 6 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, In Orion's hunting ground, 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.