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Uncommon variable star 23 EP

HIP 109890

RA 333.8568° · Dec 6.8226° · star

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Score breakdown

· 4 badges
23 pts · Uncommon
Uncommon 34 pts → Rare
  • Strongly variable +10
  • Variable star +5
  • White A-type star +5
  • A named variable star +3
Total score 23

11 more points to reach Rare.

Badges

  • Variable star · +5
  • White A-type star · +5
  • Strongly variable · +10
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 1.3 million times as much light as the Sun. It only looks ordinary because it is so far away.

What it actually is

  • Spectral class. Its spectrum reads A5.0-F0.5 — 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.

Find it in the sky

  • How to spot it. At magnitude 9.6 you'll want a small backyard telescope, over in Pegasus.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around August — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out brilliant white (B−V 0.3) — hotter and whiter than the Sun, the colour of Sirius or Vega.
  • Why no green stars. No star ever looks green: a surface hot enough to peak in green also floods out plenty of red and blue, and your eye blends the mixture back to white.

Properties

absmag
-10.44
bv
0.289
constellation
Peg
luminosity
1306170.8881
mag
9.56
name
HIP 109890
spect
A5.0-F0.5
var amplitude
0.52
var designation
DH
var max
9.29
var min
9.81

About HIP 109890

HIP 109890 is an uncommon variable star. It sits in the constellation Peg, shines at apparent magnitude 9.56 and has spectral type A5.0-F0.5.

Its spectrum reads A5.0-F0.5 — 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 HIP 109890 in the constellation Peg. At apparent magnitude 9.56, a small backyard telescope will bring it into view.

Like any astronomical target, HIP 109890 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 HIP 109890 is an uncommon variable star

HIP 109890 scores 23 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 11 points would lift it into a rarer tier.

That score comes from 4 science badges — Variable star, White A-type star, Strongly 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.