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Common star 17 EP

HD 101685

RA 175.6761° · Dec 71.3776° · star

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Score breakdown

· 4 badges
17 pts · Common
Common 22 pts → Uncommon
  • White A-type star +5
  • Blue-white star +5
  • Never sets (northern circumpolar) +4
  • Star +3
Total score 17

5 more points to reach Uncommon.

Badges

  • Star · +3
  • Never sets (northern circumpolar) · +4
  • White A-type star · +5
  • Blue-white star · +5

Trivia

Hard to believe

  • True brightness. It pours out about 946.2 thousand 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 A — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

Find it in the sky

  • How to spot it. At magnitude 9.9 you'll want a small backyard telescope, over in Draco.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around March — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out blue-white (B−V -0.1) — the hallmark of a surface far hotter than the Sun's.
  • 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.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 10910 K, against the Sun's 5778 K.

Properties

absmag
-10.11
bv
-0.058
constellation
Dra
luminosity
963829.0236
mag
9.89
name
HD 101685
spect
A

About HD 101685

HD 101685 is a common star. It sits in the constellation Dra, shines at apparent magnitude 9.89 and has spectral type A.

Its spectrum reads A — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

How to see it

Look for HD 101685 in the constellation Dra. At apparent magnitude 9.89, a small backyard telescope will bring it into view.

Like any astronomical target, HD 101685 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 101685 is a common star

HD 101685 scores 17 points on Spacedle's rarity scale, which places it in the common tier. Another 5 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Never sets (northern circumpolar), White A-type star and Blue-white 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.