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Uncommon variable star 26 EP

HD 173406

RA 281.4718° · Dec -18.3641° · star

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Score breakdown

· 6 badges
26 pts · Uncommon
Uncommon 34 pts → Rare
  • Toward the galactic centre +8
  • Variable star +5
  • White A-type star +5
  • On the zodiac +3
  • A named variable star +3
  • Barely variable (under 0.05 mag) +2
Total score 26

8 more points to reach Rare.

Badges

  • Variable star · +5
  • Toward the galactic centre · +8
  • On the zodiac · +3
  • White A-type star · +5
  • Barely variable (under 0.05 mag) · +2
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads Ap Si — 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.
  • 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 7.4 it is just past naked-eye reach — ordinary binoculars will pull it in, 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 July — 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. ≈ 16.2 million years at Voyager 1's speed (17 km/s).

Properties

absmag
0.165
bv
0.077
constellation
Sgr
dist ly
921.3447
luminosity
74.817
mag
7.42
name
HD 173406
spect
Ap Si
var amplitude
0.05
var designation
V4404
var max
7.388
var min
7.438

About HD 173406

HD 173406 is an uncommon variable star. It lies about 921.3 light-years from Earth, sits in the constellation Sgr, shines at apparent magnitude 7.42 and has spectral type Ap Si.

Its spectrum reads Ap Si — 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 173406 in the constellation Sgr. At apparent magnitude 7.42, it is an easy target for binoculars.

Like any astronomical target, HD 173406 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 173406 is an uncommon variable star

HD 173406 scores 26 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 8 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Toward the galactic centre, On the zodiac, White A-type star, Barely variable (under 0.05 mag) 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.