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Uncommon variable star 31 EP

HR 4047

RA 155.2641° · Dec 68.7477° · star

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Score breakdown

· 7 badges
31 pts · Uncommon
Uncommon 34 pts → Rare
  • Naked-eye visible +8
  • Variable star +5
  • White A-type star +5
  • Never sets (northern circumpolar) +4
  • Gently variable +4
  • A named variable star +3
  • Main-sequence star +2
Total score 31

3 more points to reach Rare.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Never sets (northern circumpolar) · +4
  • White A-type star · +5
  • Main-sequence star · +2
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads A7Vn — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.
  • Where it is in life. It is on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.
  • 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 5.9 you can see it with your own eyes from a dark site, over in Ursa Major.
  • 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 February — that's when to go looking.

Could we get there?

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

Properties

absmag
0.425
bv
0.241
constellation
UMa
dist ly
402.1654
luminosity
58.8844
mag
5.88
name
HR 4047
spect
A7Vn
var amplitude
0.07
var designation
EN
var max
5.844
var min
5.914

About HR 4047

HR 4047 is an uncommon variable star. It lies about 402.2 light-years from Earth, sits in the constellation UMa, shines at apparent magnitude 5.88 and has spectral type A7Vn.

Its spectrum reads A7Vn — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

How to see it

Look for HR 4047 in the constellation UMa. At apparent magnitude 5.88, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HR 4047 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 4047 is an uncommon variable star

HR 4047 scores 31 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 3 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Naked-eye visible, Never sets (northern circumpolar), White A-type star, Main-sequence 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.