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Rare variable star 43 EP

HR 7804

RA 305.0250° · Dec 68.8803° · star

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Score breakdown

· 8 badges
43 pts · Rare
Rare 50 pts → Epic
  • Naked-eye visible +8
  • Deep red star +8
  • Giant star +6
  • Variable star +5
  • Cool red M-type star +5
  • Never sets (northern circumpolar) +4
  • Gently variable +4
  • A named variable star +3
Total score 43

7 more points to reach Epic.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Never sets (northern circumpolar) · +4
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads M5III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • 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 5.6 you can see it with your own eyes from a dark site, over in Draco.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • 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. Hopelessly far for any craft humanity can build today.

Properties

absmag
-0.972
bv
1.472
constellation
Dra
dist ly
669.7248
luminosity
213.2063
mag
5.59
name
HR 7804
spect
M5III
var amplitude
0.21
var designation
AC
var max
5.502
var min
5.712

About HR 7804

HR 7804 is a rare variable star. It lies about 669.7 light-years from Earth, sits in the constellation Dra, shines at apparent magnitude 5.59 and has spectral type M5III.

Its spectrum reads M5III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HR 7804 in the constellation Dra. At apparent magnitude 5.59, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HR 7804 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 7804 is a rare variable star

HR 7804 scores 43 points on Spacedle's rarity scale, which places it in the rare tier. Another 7 points would lift it into a rarer tier.

That score comes from 8 science badges — Variable star, Naked-eye visible, Never sets (northern circumpolar), Cool red M-type star, Giant star, Deep red 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.