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Rare variable star 42 EP

HR 3147

RA 119.7107° · Dec -60.8245° · star

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Score breakdown

· 8 badges
42 pts · Rare
Rare 50 pts → Epic
  • Naked-eye visible +8
  • 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
  • Gently variable +4
  • A named variable star +3
Total score 42

8 more points to reach Epic.

Badges

  • Variable star · +5
  • Distant (over 1,000 light-years) · +6
  • Naked-eye visible · +8
  • Hot blue B-type star · +6
  • Subgiant (leaving the main sequence) · +5
  • Blue-white star · +5
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads B2IVnpe — 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 5.8 you can see it with your own eyes from a dark site, over in Carina.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • Best time of year. It stands highest in the middle of the night around January — that's when to go looking.

Could we get there?

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

Properties

absmag
-1.773
bv
-0.082
constellation
Car
dist ly
1052.116
luminosity
445.8615
mag
5.77
name
HR 3147
spect
B2IVnpe
var amplitude
0.11
var designation
V374
var max
5.698
var min
5.808

About HR 3147

HR 3147 is a rare variable star. It lies about 1,052.1 light-years from Earth, sits in the constellation Car, shines at apparent magnitude 5.77 and has spectral type B2IVnpe.

Its spectrum reads B2IVnpe — 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 3147 in the constellation Car. At apparent magnitude 5.77, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HR 3147 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 3147 is a rare variable star

HR 3147 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), Naked-eye visible, Hot blue B-type star, Subgiant (leaving the main sequence), Blue-white star, Gently variable 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.