Uncommon star 25 EP

HD 171543

RA 279.1217° · Dec -27.0280° · star

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Score breakdown

· 5 badges

25 pts · Uncommon

Uncommon 34 pts → Rare

Toward the galactic centre +8
Deep red star +8
Star +3
On the zodiac +3
Orange K-type star +3

Total score 25

9 more points to reach Rare.

Badges

Star · +3
Toward the galactic centre · +8
On the zodiac · +3
Orange K-type star · +3
Deep red star · +8

Trivia

Hard to believe

True brightness. It pours out about 2.6 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 K4/K5 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

Find it in the sky

How to spot it. At magnitude 8.8 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Sagittarius.
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 June — 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 1.7) — one of the coolest surfaces a star can have while still fusing.

By the numbers

Surface temperature. Its colour puts the surface at roughly 3540 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: -11.2
bv: 1.678
constellation: Sgr
luminosity: 2630267.9919
mag: 8.8
name: HD 171543
spect: K4/K5

Nearby objects

About HD 171543

HD 171543 is an uncommon star. It sits in the constellation Sgr, shines at apparent magnitude 8.8 and has spectral type K4/K5.

Its spectrum reads K4/K5 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

How to see it

Look for HD 171543 in the constellation Sgr. At apparent magnitude 8.8, it is an easy target for binoculars.

Like any astronomical target, HD 171543 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 171543 is an uncommon star

HD 171543 scores 25 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 9 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, Toward the galactic centre, On the zodiac, Orange K-type 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.