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Rare variable star 39 EP

HD 156801

RA 259.8838° · Dec 1.5151° · star

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Score breakdown

· 5 badges
39 pts · Rare
Rare 50 pts → Epic
  • Dramatic variable (over 2 magnitudes) +20
  • Deep red star +8
  • Variable star +5
  • Orange K-type star +3
  • A named variable star +3
Total score 39

11 more points to reach Epic.

Badges

  • Variable star · +5
  • Orange K-type star · +3
  • Deep red star · +8
  • Dramatic variable (over 2 magnitudes) · +20
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 469.9 thousand 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 K3ep-M7.5e — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions 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.

Find it in the sky

  • How to spot it. At magnitude 10.7 you'll want a small backyard telescope, 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 3790 K, against the Sun's 5778 K.

Properties

absmag
-9.35
bv
1.5
constellation
Oph
luminosity
478630.0923
mag
10.65
name
HD 156801
spect
K3ep-M7.5e
var amplitude
3.59
var designation
Z
var max
8.304
var min
11.894

About HD 156801

HD 156801 is a rare variable star. It sits in the constellation Oph, shines at apparent magnitude 10.65 and has spectral type K3ep-M7.5e.

Its spectrum reads K3ep-M7.5e — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

How to see it

Look for HD 156801 in the constellation Oph. At apparent magnitude 10.65, a small backyard telescope will bring it into view.

Like any astronomical target, HD 156801 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 156801 is a rare variable star

HD 156801 scores 39 points on Spacedle's rarity scale, which places it in the rare tier. Another 11 points would lift it into a rarer tier.

That score comes from 5 science badges — Variable star, Orange K-type star, Deep red star, Dramatic variable (over 2 magnitudes) 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.