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Rare variable star 40 EP

HD 15785

RA 38.7002° · Dec 60.5521° · star

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Score breakdown

· 6 badges
40 pts · Rare
Rare 50 pts → Epic
  • Supergiant +18
  • Hot blue B-type star +6
  • Variable star +5
  • Never sets (northern circumpolar) +4
  • Gently variable +4
  • A named variable star +3
Total score 40

10 more points to reach Epic.

Badges

  • Variable star · +5
  • Never sets (northern circumpolar) · +4
  • Hot blue B-type star · +6
  • Supergiant · +18
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads B1Iab — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
  • Where it is in life. It is a supergiant. Drop it where the Sun is and its surface would engulf the inner planets.
  • 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 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cassiopeia.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around October — that's when to go looking.

Could we get there?

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

Properties

absmag
1.053
bv
0.495
constellation
Cas
dist ly
948.128
luminosity
33.0217
mag
8.37
name
HD 15785
spect
B1Iab
var amplitude
0.12
var designation
V790
var max
8.314
var min
8.434

About HD 15785

HD 15785 is a rare variable star. It lies about 948.1 light-years from Earth, sits in the constellation Cas, shines at apparent magnitude 8.37 and has spectral type B1Iab.

Its spectrum reads B1Iab — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 15785 in the constellation Cas. At apparent magnitude 8.37, it is an easy target for binoculars.

Like any astronomical target, HD 15785 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 15785 is a rare variable star

HD 15785 scores 40 points on Spacedle's rarity scale, which places it in the rare tier. Another 10 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Never sets (northern circumpolar), Hot blue B-type star, Supergiant, 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.