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Uncommon variable star 28 EP

HD 31660

RA 73.7901° · Dec -49.9455° · star

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Score breakdown

· 6 badges
28 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • Variable star +5
  • Subgiant (leaving the main sequence) +5
  • Gently variable +4
  • Orange K-type star +3
  • A named variable star +3
Total score 28

6 more points to reach Rare.

Badges

  • Variable star · +5
  • Orange K-type star · +3
  • Subgiant (leaving the main sequence) · +5
  • Deep red star · +8
  • Gently variable · +4
  • A named variable star · +3

Trivia

Hard to believe

  • True brightness. It pours out about 4.2 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 K3/K4IV — 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 8.3 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Pictor.
  • 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 December — 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 1.7) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3520 K, against the Sun's 5778 K.

Properties

absmag
-11.73
bv
1.699
constellation
Pic
luminosity
4285485.204
mag
8.27
name
HD 31660
spect
K3/K4IV
var amplitude
0.29
var designation
UZ
var max
8.173
var min
8.463

About HD 31660

HD 31660 is an uncommon variable star. It sits in the constellation Pic, shines at apparent magnitude 8.27 and has spectral type K3/K4IV.

Its spectrum reads K3/K4IV — 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 31660 in the constellation Pic. At apparent magnitude 8.27, it is an easy target for binoculars.

Like any astronomical target, HD 31660 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 31660 is an uncommon variable star

HD 31660 scores 28 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 6 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Orange K-type star, Subgiant (leaving the main sequence), Deep red star, 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.