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Rare variable star 42 EP

HD 163868

RA 269.9851° · Dec -33.4083° · star

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Score breakdown

· 9 badges
42 pts · Rare
Rare 50 pts → Epic
  • Toward the galactic centre +8
  • Distant (over 1,000 light-years) +6
  • Hot blue B-type star +6
  • Variable star +5
  • Blue-white star +5
  • Gently variable +4
  • On the zodiac +3
  • A named variable star +3
  • Main-sequence star +2
Total score 42

8 more points to reach Epic.

Badges

  • Variable star · +5
  • Distant (over 1,000 light-years) · +6
  • Toward the galactic centre · +8
  • On the zodiac · +3
  • Hot blue B-type star · +6
  • Main-sequence star · +2
  • Blue-white star · +5
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads B2/B3V:ne — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
  • 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 7.3 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 June — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Getting there

  • Aboard Voyager 1. ≈ 33.7 million years at Voyager 1's speed (17 km/s).

Properties

absmag
-1.498
bv
-0.035
constellation
Sgr
dist ly
1918.5647
luminosity
346.0987
mag
7.35
name
HD 163868
spect
B2/B3V:ne
var amplitude
0.08
var designation
V3984
var max
7.314
var min
7.394

About HD 163868

HD 163868 is a rare variable star. It lies about 1,918.6 light-years from Earth, sits in the constellation Sgr, shines at apparent magnitude 7.35 and has spectral type B2/B3V:ne.

Its spectrum reads B2/B3V:ne — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 163868 in the constellation Sgr. At apparent magnitude 7.35, it is an easy target for binoculars.

Like any astronomical target, HD 163868 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 163868 is a rare variable star

HD 163868 scores 42 points on Spacedle's rarity scale, which places it in the rare tier. Another 8 points would lift it into a rarer tier.

That score comes from 9 science badges — Variable star, Distant (over 1,000 light-years), Toward the galactic centre, On the zodiac, Hot blue B-type star, Main-sequence star, Blue-white star and Gently variable — 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.