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Uncommon variable star 22 EP

HD 199757

RA 315.1467° · Dec -42.6556° · star

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Score breakdown

· 5 badges
22 pts · Uncommon
Uncommon 34 pts → Rare
  • Variable star +5
  • White A-type star +5
  • Subgiant (leaving the main sequence) +5
  • Gently variable +4
  • A named variable star +3
Total score 22

12 more points to reach Rare.

Badges

  • Variable star · +5
  • White A-type star · +5
  • Subgiant (leaving the main sequence) · +5
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads A6IV — 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.
  • 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 9.5 you'll want a small backyard telescope, over in Microscopium.
  • 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 August — that's when to go looking.

Could we get there?

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

Properties

absmag
2.249
bv
0.236
constellation
Mic
dist ly
911.0503
luminosity
10.9749
mag
9.48
name
HD 199757
spect
A6IV
var amplitude
0.33
var designation
ZZ
var max
9.272
var min
9.602

About HD 199757

HD 199757 is an uncommon variable star. It lies about 911.1 light-years from Earth, sits in the constellation Mic, shines at apparent magnitude 9.48 and has spectral type A6IV.

Its spectrum reads A6IV — 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 199757 in the constellation Mic. At apparent magnitude 9.48, a small backyard telescope will bring it into view.

Like any astronomical target, HD 199757 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 199757 is an uncommon variable star

HD 199757 scores 22 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 12 points would lift it into a rarer tier.

That score comes from 5 science badges — Variable star, White A-type star, Subgiant (leaving the main sequence), 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.