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Common star 21 EP

HR 1645

RA 75.9720° · Dec -24.3882° · star

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Score breakdown

· 4 badges
21 pts · Common
Common 22 pts → Uncommon
  • Naked-eye visible +8
  • White A-type star +5
  • Subgiant (leaving the main sequence) +5
  • Star +3
Total score 21

1 more point to reach Uncommon.

Badges

  • Star · +3
  • Naked-eye visible · +8
  • White A-type star · +5
  • Subgiant (leaving the main sequence) · +5

Trivia

What it actually is

  • Spectral class. Its spectrum reads A2IV — 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 a subgiant, caught in the act of leaving the main sequence as the hydrogen in its core runs out.

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 Lepus.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around December — that's when to go looking.

Could we get there?

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

Getting there

  • Aboard Voyager 1. ≈ 3.3 million years at Voyager 1's speed (17 km/s).

Properties

absmag
1.786
bv
0.094
constellation
Lep
dist ly
189.736
luminosity
16.8112
mag
5.61
name
HR 1645
spect
A2IV

About HR 1645

HR 1645 is a common star. It lies about 189.7 light-years from Earth, sits in the constellation Lep, shines at apparent magnitude 5.61 and has spectral type A2IV.

Its spectrum reads A2IV — 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 1645 in the constellation Lep. At apparent magnitude 5.61, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, HR 1645 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 1645 is a common star

HR 1645 scores 21 points on Spacedle's rarity scale, which places it in the common tier. Another 1 point would lift it into a rarer tier.

That score comes from 4 science badges — Star, Naked-eye visible, White A-type star and Subgiant (leaving the main sequence) — 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.