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Rare variable star 35 EP

25 Ser

RA 236.5235° · Dec -1.8042° · star

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Score breakdown

· 7 badges
35 pts · Rare
Rare 50 pts → Epic
  • Naked-eye visible +8
  • Hot blue B-type star +6
  • Giant star +6
  • Variable star +5
  • Blue-white star +5
  • A named variable star +3
  • Barely variable (under 0.05 mag) +2
Total score 35

15 more points to reach Epic.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Hot blue B-type star · +6
  • Giant star · +6
  • Blue-white star · +5
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads B8III — 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 a giant. It has already exhausted its core hydrogen and swollen up enormously in response.
  • 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 5.4 you can see it with your own eyes from a dark site, over in Serpens.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • 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
-0.308
bv
-0.035
constellation
Ser
dist ly
449.8702
luminosity
115.6645
mag
5.39
name
25 Ser
spect
B8III
var amplitude
0.05
var designation
PT
var max
5.365
var min
5.415

About 25 Ser

25 Ser is a rare variable star. It lies about 449.9 light-years from Earth, sits in the constellation Ser, shines at apparent magnitude 5.39 and has spectral type B8III.

Its spectrum reads B8III — 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 25 Ser in the constellation Ser. At apparent magnitude 5.39, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 25 Ser 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 25 Ser is a rare variable star

25 Ser scores 35 points on Spacedle's rarity scale, which places it in the rare tier. Another 15 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Naked-eye visible, Hot blue B-type star, Giant star, Blue-white star, 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.