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Uncommon variable star 25 EP

HD 135681

RA 229.2025° · Dec -13.0392° · star

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Score breakdown

· 6 badges
25 pts · Uncommon
Uncommon 34 pts → Rare
  • Variable star +5
  • White A-type star +5
  • Subgiant (leaving the main sequence) +5
  • Gently variable +4
  • On the zodiac +3
  • A named variable star +3
Total score 25

9 more points to reach Rare.

Badges

  • Variable star · +5
  • On the zodiac · +3
  • White A-type star · +5
  • Subgiant (leaving the main sequence) · +5
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads A3IV — 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.
  • Where it is in life. It is a subgiant, caught in the act of leaving the main sequence as the hydrogen in its core runs out.
  • 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 7.2 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Libra.
  • 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 May — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Properties

absmag
1.928
bv
0.221
constellation
Lib
dist ly
378.3713
luminosity
14.7503
mag
7.25
name
HD 135681
spect
A3IV
var amplitude
0.38
var designation
ES
var max
7.122
var min
7.502

About HD 135681

HD 135681 is an uncommon variable star. It lies about 378.4 light-years from Earth, sits in the constellation Lib, shines at apparent magnitude 7.25 and has spectral type A3IV.

Its spectrum reads A3IV — 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 135681 in the constellation Lib. At apparent magnitude 7.25, it is an easy target for binoculars.

Like any astronomical target, HD 135681 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 135681 is an uncommon variable star

HD 135681 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 6 science badges — Variable star, On the zodiac, White A-type star, Subgiant (leaving the main sequence), 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.