← Back to dex
Uncommon star 22 EP

HD 9858

RA 23.5844° · Dec -64.5188° · star

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

Computing the sky for your location…

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 2.1 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 M2/M3III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

Find it in the sky

  • How to spot it. At magnitude 9 you'll want a small backyard telescope, over in Hydrus.
  • 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 October — 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 3770 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
-10.99
bv
1.518
constellation
Hyi
luminosity
2167704.1048
mag
9.01
name
HD 9858
spect
M2/M3III

About HD 9858

HD 9858 is an uncommon star. It sits in the constellation Hyi, shines at apparent magnitude 9.01 and has spectral type M2/M3III.

Its spectrum reads M2/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 9858 in the constellation Hyi. At apparent magnitude 9.01, a small backyard telescope will bring it into view.

Like any astronomical target, HD 9858 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 9858 is an uncommon star

HD 9858 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.