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Uncommon variable star 31 EP

HD 153869

RA 255.4452° · Dec 6.6099° · star

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Score breakdown

· 6 badges
31 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • Red dwarf +6
  • Variable star +5
  • Cool red M-type star +5
  • Gently variable +4
  • A named variable star +3
Total score 31

3 more points to reach Rare.

Badges

  • Variable star · +5
  • Cool red M-type star · +5
  • Deep red star · +8
  • Red dwarf · +6
  • Gently variable · +4
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 2.8 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 M4 — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • 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 8.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Ophiuchus.
  • 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 June — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out deep orange-red (B−V 1.5) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3820 K, against the Sun's 5778 K.

Properties

absmag
-11.27
bv
1.481
constellation
Oph
luminosity
2805433.638
mag
8.73
name
HD 153869
spect
M4
var amplitude
0.2
var designation
V2361
var max
8.614
var min
8.814

About HD 153869

HD 153869 is an uncommon variable star. It sits in the constellation Oph, shines at apparent magnitude 8.73 and has spectral type M4.

Its spectrum reads M4 — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HD 153869 in the constellation Oph. At apparent magnitude 8.73, it is an easy target for binoculars.

Like any astronomical target, HD 153869 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 153869 is an uncommon variable star

HD 153869 scores 31 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 3 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Cool red M-type star, Deep red star, Red dwarf, 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.