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Rare variable star 43 EP

HR 3698

RA 140.4304° · Dec 56.6992° · 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 M4IIIa — 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 5.8 you can see it with your own eyes from a dark site, over in Ursa Major.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around February — that's when to go looking.

Could we get there?

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

Properties

absmag
-1.023
bv
1.511
constellation
UMa
dist ly
751.5114
luminosity
223.4601
mag
5.79
name
HR 3698
spect
M4IIIa
var amplitude
0.36
var designation
CG
var max
5.621
var min
5.981

About HR 3698

HR 3698 is a rare variable star. It lies about 751.5 light-years from Earth, sits in the constellation UMa, shines at apparent magnitude 5.79 and has spectral type M4IIIa.

Its spectrum reads M4IIIa — 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 3698 in the constellation UMa. At apparent magnitude 5.79, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HR 3698 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 3698 is a rare variable star

HR 3698 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.