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Uncommon variable star 28 EP

21 Vul

RA 303.5605° · Dec 28.6948° · star

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Score breakdown

· 6 badges
28 pts · Uncommon
Uncommon 34 pts → Rare
  • Naked-eye visible +8
  • Variable star +5
  • White A-type star +5
  • Subgiant (leaving the main sequence) +5
  • A named variable star +3
  • Barely variable (under 0.05 mag) +2
Total score 28

6 more points to reach Rare.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • White A-type star · +5
  • Subgiant (leaving the main sequence) · +5
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads A7IVn — 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 5.2 you can see it with your own eyes from a dark site, over in Vulpecula.
  • 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 July — that's when to go looking.

Could we get there?

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

Properties

absmag
0.391
bv
0.191
constellation
Vul
dist ly
297.3163
luminosity
60.7575
mag
5.19
name
21 Vul
spect
A7IVn
var amplitude
0.02
var designation
NU
var max
5.178
var min
5.198

About 21 Vul

21 Vul is an uncommon variable star. It lies about 297.3 light-years from Earth, sits in the constellation Vul, shines at apparent magnitude 5.19 and has spectral type A7IVn.

Its spectrum reads A7IVn — 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 21 Vul in the constellation Vul. At apparent magnitude 5.19, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 21 Vul 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 21 Vul is an uncommon variable star

21 Vul scores 28 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 6 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Naked-eye visible, White A-type star, Subgiant (leaving the main sequence), Barely variable (under 0.05 mag) 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.