About HD 256138
HD 256138 is a trash star. It sits in the constellation Gem, shines at apparent magnitude 8.99 and has spectral type F5.
Its spectrum reads F5 — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Trash star 9 EP
HD 256138
RA 95.8175° · Dec 24.1293° · star
Score breakdown
· 3 badgesTrash 15 pts → Common
- Star +3
- On the zodiac +3
- Yellow-white F-type star +3
Total score 9
6 more points to reach Common.
Badges
- Star · +3
- On the zodiac · +3
- Yellow-white F-type star · +3
Trivia
Hard to believe
- True brightness. It pours out about 2.2 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 F5 — 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 9 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Gemini.
- 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 December — that's when to go looking.
Its true colour
- Its true colour. Measured through blue and visual filters it comes out yellow (B−V 0.6) — almost exactly the Sun's own shade — a stellar twin in colour, if not in size.
- 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 5800 K, against the Sun's 5778 K.
Properties
- absmag
- -11.01
- bv
- 0.643
- constellation
- Gem
- luminosity
- 2208004.733
- mag
- 8.99
- name
- HD 256138
- spect
- F5
How to see it
Look for HD 256138 in the constellation Gem. At apparent magnitude 8.99, it is an easy target for binoculars.
Like any astronomical target, HD 256138 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 256138 is a trash star
HD 256138 scores 9 points on Spacedle's rarity scale, which places it in the trash tier. Another 6 points would lift it into a rarer tier.
That score comes from 3 science badges — Star, On the zodiac and Yellow-white F-type 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.