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Uncommon star 25 EP

HD 170798

RA 278.0562° · Dec -22.0560° · star

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Score breakdown

· 5 badges
25 pts · Uncommon
Uncommon 34 pts → Rare
  • Toward the galactic centre +8
  • Giant star +6
  • White A-type star +5
  • Star +3
  • On the zodiac +3
Total score 25

9 more points to reach Rare.

Badges

  • Star · +3
  • Toward the galactic centre · +8
  • On the zodiac · +3
  • White A-type star · +5
  • Giant star · +6

Trivia

What it actually is

  • Spectral class. Its spectrum reads A2III — 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 giant. It has already exhausted its core hydrogen and swollen up enormously in response.

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 9.3 you'll want a small backyard telescope, over in Sagittarius.
  • 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 June — 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. ≈ 9.6 million years at Voyager 1's speed (17 km/s).

Properties

absmag
3.234
bv
0.31
constellation
Sgr
dist ly
545.4114
luminosity
4.43
mag
9.35
name
HD 170798
spect
A2III

About HD 170798

HD 170798 is an uncommon star. It lies about 545.4 light-years from Earth, sits in the constellation Sgr, shines at apparent magnitude 9.35 and has spectral type A2III.

Its spectrum reads A2III — 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 HD 170798 in the constellation Sgr. At apparent magnitude 9.35, a small backyard telescope will bring it into view.

Like any astronomical target, HD 170798 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 HD 170798 is an uncommon star

HD 170798 scores 25 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 9 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, Toward the galactic centre, On the zodiac, White A-type star and Giant 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.