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Uncommon variable star 33 EP

HD 138900

RA 232.5006° · Dec 70.3862° · star

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Score breakdown

· 7 badges
33 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • Distant (over 1,000 light-years) +6
  • Variable star +5
  • Never sets (northern circumpolar) +4
  • Gently variable +4
  • Orange K-type star +3
  • A named variable star +3
Total score 33

1 more point to reach Rare.

Badges

  • Variable star · +5
  • Distant (over 1,000 light-years) · +6
  • Never sets (northern circumpolar) · +4
  • Orange K-type star · +3
  • Deep red star · +8
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads K5 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.
  • It changes. This star does not hold still: its brightness rises and falls on a rhythm of hours, days or years, either pulsing in size or being eclipsed by a companion.

Sense of scale

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Ursa Minor.
  • 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 May — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Getting there

  • Aboard Voyager 1. ≈ 34.5 million years at Voyager 1's speed (17 km/s).

Properties

absmag
-0.499
bv
1.519
constellation
UMi
dist ly
1964.7951
luminosity
137.9113
mag
8.4
name
HD 138900
spect
K5
var amplitude
0.2
var designation
TZ
var max
8.275
var min
8.475

Nearby objects

About HD 138900

HD 138900 is an uncommon variable star. It lies about 1,964.8 light-years from Earth, sits in the constellation UMi, shines at apparent magnitude 8.4 and has spectral type K5.

Its spectrum reads 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 138900 in the constellation UMi. At apparent magnitude 8.4, it is an easy target for binoculars.

Like any astronomical target, HD 138900 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 138900 is an uncommon variable star

HD 138900 scores 33 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 1 point would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Distant (over 1,000 light-years), Never sets (northern circumpolar), Orange K-type star, Deep red star, Gently variable and A named variable 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.