About HD 239856
HD 239856 is an uncommon star. It sits in the constellation Cep, shines at apparent magnitude 8.53 and has spectral type F2Iab.
Its spectrum reads F2Iab — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Uncommon star 28 EP
HD 239856
RA 331.8208° · Dec 56.2340° · star
Score breakdown
· 4 badgesUncommon 34 pts → Rare
- Supergiant +18
- Never sets (northern circumpolar) +4
- Star +3
- Yellow-white F-type star +3
Total score 28
6 more points to reach Rare.
Badges
- Star · +3
- Never sets (northern circumpolar) · +4
- Yellow-white F-type star · +3
- Supergiant · +18
Trivia
Hard to believe
- True brightness. It pours out about 3.3 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 F2Iab — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
- Where it is in life. It is a supergiant. Drop it where the Sun is and its surface would engulf the inner planets.
Find it in the sky
- How to spot it. At magnitude 8.5 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cepheus.
- Northern sky. It rides the northern half of the sky — an easier target the further north you are.
- Best time of year. It stands highest in the middle of the night around August — that's when to go looking.
Its true colour
- Its true colour. Measured through blue and visual filters it comes out orange (B−V 1) — cooler than the Sun, and the kind of star that burns steadily for tens of billions of years.
By the numbers
- Surface temperature. Its colour puts the surface at roughly 4720 K, against the Sun's 5778 K.
Properties
- absmag
- -11.47
- bv
- 1.011
- constellation
- Cep
- luminosity
- 3372873.0866
- mag
- 8.53
- name
- HD 239856
- spect
- F2Iab
How to see it
Look for HD 239856 in the constellation Cep. At apparent magnitude 8.53, it is an easy target for binoculars.
Like any astronomical target, HD 239856 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 239856 is an uncommon star
HD 239856 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 4 science badges — Star, Never sets (northern circumpolar), Yellow-white F-type star and Supergiant — 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.