← Back to dex
Common variable star 17 EP

40 Ser

RA 238.6678° · Dec 8.5803° · star

Loading sky survey…
🌌 View in 3D star map
Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 5 badges
17 pts · Common
Common 22 pts → Uncommon
  • Variable star +5
  • White A-type star +5
  • A named variable star +3
  • Main-sequence star +2
  • Barely variable (under 0.05 mag) +2
Total score 17

5 more points to reach Uncommon.

Badges

  • Variable star · +5
  • White A-type star · +5
  • Main-sequence star · +2
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads A7Vn — 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 on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.
  • 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 6.3 it is just past naked-eye reach — ordinary binoculars will pull it in, 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
1.796
bv
0.171
constellation
Ser
dist ly
257.221
luminosity
16.6571
mag
6.28
name
40 Ser
spect
A7Vn
var amplitude
0.03
var designation
FP
var max
6.269
var min
6.299

About 40 Ser

40 Ser is a common variable star. It lies about 257.2 light-years from Earth, sits in the constellation Ser, shines at apparent magnitude 6.28 and has spectral type A7Vn.

Its spectrum reads A7Vn — 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 40 Ser in the constellation Ser. At apparent magnitude 6.28, it is an easy target for binoculars.

Like any astronomical target, 40 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 40 Ser is a common variable star

40 Ser 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 5 science badges — Variable star, White A-type star, Main-sequence 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.