About HD 9973
HD 9973 is an uncommon star. It sits in the constellation Cas, shines at apparent magnitude 6.88 and has spectral type F5Iab.
Its spectrum reads F5Iab — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Uncommon star 28 EP
HD 9973
RA 24.7799° · Dec 61.0791° · 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
What it actually is
- Spectral class. Its spectrum reads F5Iab — 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 6.9 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 orange (B−V 0.8) — cooler than the Sun, and the kind of star that burns steadily for tens of billions of years.
- Why no green stars. No star ever looks green: a surface hot enough to peak in green also floods out plenty of red and blue, and your eye blends the mixture back to white.
By the numbers
- Surface temperature. Its colour puts the surface at roughly 5190 K, against the Sun's 5778 K.
Properties
- absmag
- -13.12
- bv
- 0.83
- constellation
- Cas
- luminosity
- 15417004.5295
- mag
- 6.88
- name
- HD 9973
- spect
- F5Iab
How to see it
Look for HD 9973 in the constellation Cas. At apparent magnitude 6.88, it is an easy target for binoculars.
Like any astronomical target, HD 9973 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 9973 is an uncommon star
HD 9973 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.