Trash star 11 EP

HD 198931

RA 313.0405° · Dec 44.4346° · star

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Score breakdown

· 3 badges

11 pts · Trash

Trash 15 pts → Common

Hot blue B-type star +6
Star +3
Main-sequence star +2

Total score 11

4 more points to reach Common.

Badges

Star · +3
Hot blue B-type star · +6
Main-sequence star · +2

Trivia

Hard to believe

True brightness. It pours out about 2.8 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 B1Vnne... — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
Where it is in life. It is on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.

Find it in the sky

How to spot it. At magnitude 8.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cygnus.
Northern sky. It rides the northern half of the sky — an easier target the further north you are.
Best time of year. It stands highest in the middle of the night around August — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out yellow-white (B−V 0.5) — a shade brighter and crisper than our own Sun.
Why no green stars. No star ever looks green: a surface hot enough to peak in green also floods out plenty of red and blue, and your eye blends the mixture back to white.

Properties

absmag: -11.28
bv: 0.512
constellation: Cyg
luminosity: 2831391.9958
mag: 8.72
name: HD 198931
spect: B1Vnne...

Nearby objects

About HD 198931

HD 198931 is a trash star. It sits in the constellation Cyg, shines at apparent magnitude 8.72 and has spectral type B1Vnne....

Its spectrum reads B1Vnne... — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 198931 in the constellation Cyg. At apparent magnitude 8.72, it is an easy target for binoculars.

Like any astronomical target, HD 198931 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 198931 is a trash star

HD 198931 scores 11 points on Spacedle's rarity scale, which places it in the trash tier. Another 4 points would lift it into a rarer tier.

That score comes from 3 science badges — Star, Hot blue B-type star and Main-sequence 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.