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Trash star 14 EP

HD 121331

RA 208.8305° · Dec -26.4326° · star

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Score breakdown

· 3 badges
14 pts · Trash
Trash 15 pts → Common
  • Giant star +6
  • Cool red M-type star +5
  • Star +3
Total score 14

1 more point to reach Common.

Badges

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

Trivia

What it actually is

  • Spectral class. Its spectrum reads M5III — 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 7.8 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Hydra.
  • 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 April — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out orange (B−V 1.3) — cooler than the Sun, and the kind of star that burns steadily for tens of billions of years.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 4080 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
-12.21
bv
1.321
constellation
Hya
luminosity
6668067.6921
mag
7.79
name
HD 121331
spect
M5III

Nearby objects

About HD 121331

HD 121331 is a trash star. It sits in the constellation Hya, shines at apparent magnitude 7.79 and has spectral type M5III.

Its spectrum reads M5III — 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 121331 in the constellation Hya. At apparent magnitude 7.79, it is an easy target for binoculars.

Like any astronomical target, HD 121331 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 121331 is a trash star

HD 121331 scores 14 points on Spacedle's rarity scale, which places it in the trash tier. Another 1 point would lift it into a rarer tier.

That score comes from 3 science badges — Star, Cool red M-type star and Giant 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.