About HD 22704
HD 22704 is a trash star. It sits in the constellation Hor, shines at apparent magnitude 8.55 and has spectral type F3/F5IV.
Its spectrum reads F3/F5IV — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Trash star 11 EP
HD 22704
RA 54.3087° · Dec -44.4720° · star
Score breakdown
· 3 badgesTrash 15 pts → Common
- Subgiant (leaving the main sequence) +5
- Star +3
- Yellow-white F-type star +3
Total score 11
4 more points to reach Common.
Badges
- Star · +3
- Yellow-white F-type star · +3
- Subgiant (leaving the main sequence) · +5
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 F3/F5IV — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Find it in the sky
- How to spot it. At magnitude 8.6 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Horologium.
- 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 November — that's when to go looking.
Its true colour
- Its true colour. Measured through blue and visual filters it comes out yellow-white (B−V 0.5) — a shade brighter and crisper than our own Sun.
- 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 6500 K, against the Sun's 5778 K.
Properties
- absmag
- -11.45
- bv
- 0.477
- constellation
- Hor
- luminosity
- 3311311.2148
- mag
- 8.55
- name
- HD 22704
- spect
- F3/F5IV
Nearby objects
How to see it
Look for HD 22704 in the constellation Hor. At apparent magnitude 8.55, it is an easy target for binoculars.
Like any astronomical target, HD 22704 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 22704 is a trash star
HD 22704 scores 11 points on Spacedle's rarity scale, which places it in the trash tier. Another 4 points would lift it into a rarer tier.
That score comes from 3 science badges — Star, Yellow-white F-type star and Subgiant (leaving the main sequence) — 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.