About HD 12399
HD 12399 is an epic variable star. It sits in the constellation Cas, shines at apparent magnitude 7.53 and has spectral type G5Ia.
Its spectrum reads G5Ia — a G-type star: the very same spectral class as our own Sun.
Epic variable star 50 EP
HD 12399
RA 30.9547° · Dec 64.2375° · star
Score breakdown
· 7 badgesEpic 78 pts → Anomaly
- Supergiant +18
- Sun-like G-type star +8
- Deep red star +8
- Variable star +5
- Never sets (northern circumpolar) +4
- Gently variable +4
- A named variable star +3
Total score 50
28 more points to reach Anomaly.
Badges
- Variable star · +5
- Never sets (northern circumpolar) · +4
- Sun-like G-type star · +8
- Supergiant · +18
- Deep red star · +8
- Gently variable · +4
- A named variable star · +3
Trivia
What it actually is
- Spectral class. Its spectrum reads G5Ia — a G-type star: the very same spectral class as our own Sun.
- Where it is in life. It is a luminous supergiant — among the largest and rarest stars in the galaxy.
- 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 7.5 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.
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 3550 K, against the Sun's 5778 K.
Properties
- absmag
- -12.47
- bv
- 1.677
- constellation
- Cas
- luminosity
- 8472274.1414
- mag
- 7.53
- name
- HD 12399
- spect
- G5Ia
- var amplitude
- 0.13
- var designation
- V781
- var max
- 7.47
- var min
- 7.6
How to see it
Look for HD 12399 in the constellation Cas. At apparent magnitude 7.53, it is an easy target for binoculars.
Like any astronomical target, HD 12399 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 12399 is an epic variable star
HD 12399 scores 50 points on Spacedle's rarity scale, which places it in the epic tier. Another 28 points would lift it into a rarer tier.
That score comes from 7 science badges — Variable star, Never sets (northern circumpolar), Sun-like G-type star, Supergiant, 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.