← Back to dex
Rare variable star 44 EP

42The Oph

RA 260.5024° · Dec -24.9995° · star

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

Computing the sky for your location…

Score breakdown

· 8 badges
44 pts · Rare
Rare 50 pts → Epic
  • Intrinsically luminous (Mv < −2) +10
  • Naked-eye visible +8
  • Hot blue B-type star +6
  • Variable star +5
  • Subgiant (leaving the main sequence) +5
  • Blue-white star +5
  • A named variable star +3
  • Barely variable (under 0.05 mag) +2
Total score 44

6 more points to reach Epic.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Hot blue B-type star · +6
  • Subgiant (leaving the main sequence) · +5
  • Blue-white star · +5
  • Intrinsically luminous (Mv < −2) · +10
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads B2IV — 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 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 3.3 you can see it with your own eyes from a dark site, over in Ophiuchus.
  • 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 June — that's when to go looking.

Could we get there?

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

Properties

absmag
-2.36
bv
-0.186
constellation
Oph
dist ly
436.0373
luminosity
765.5966
mag
3.27
name
42The Oph
spect
B2IV
var amplitude
0.03
var designation
The
var max
3.257
var min
3.287

About 42The Oph

42The Oph is a rare variable star. It lies about 436 light-years from Earth, sits in the constellation Oph, shines at apparent magnitude 3.27 and has spectral type B2IV.

Its spectrum reads B2IV — 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 42The Oph in the constellation Oph. At apparent magnitude 3.27, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 42The Oph 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 42The Oph is a rare variable star

42The Oph scores 44 points on Spacedle's rarity scale, which places it in the rare tier. Another 6 points would lift it into a rarer tier.

That score comes from 8 science badges — Variable star, Naked-eye visible, Hot blue B-type star, Subgiant (leaving the main sequence), Blue-white star, Intrinsically luminous (Mv < −2), 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.