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Rare variable star 42 EP

HR 7554

RA 297.5728° · Dec 7.9024° · star

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Score breakdown

· 8 badges
42 pts · Rare
Rare 50 pts → Epic
  • Intrinsically luminous (Mv < −2) +10
  • Distant (over 1,000 light-years) +6
  • 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 42

8 more points to reach Epic.

Badges

  • Variable star · +5
  • Distant (over 1,000 light-years) · +6
  • 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 B2.5IVe — 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 6.5 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Aquila.
  • 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 July — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Properties

absmag
-2.128
bv
-0.086
constellation
Aql
dist ly
1725.693
luminosity
618.3011
mag
6.49
name
HR 7554
spect
B2.5IVe
var amplitude
0.05
var designation
V1339
var max
6.464
var min
6.514

About HR 7554

HR 7554 is a rare variable star. It lies about 1,725.7 light-years from Earth, sits in the constellation Aql, shines at apparent magnitude 6.49 and has spectral type B2.5IVe.

Its spectrum reads B2.5IVe — 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 HR 7554 in the constellation Aql. At apparent magnitude 6.49, it is an easy target for binoculars.

Like any astronomical target, HR 7554 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 HR 7554 is a rare variable star

HR 7554 scores 42 points on Spacedle's rarity scale, which places it in the rare tier. Another 8 points would lift it into a rarer tier.

That score comes from 8 science badges — Variable star, Distant (over 1,000 light-years), 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.