About HD 31730
HD 31730 is a trash star. It sits in the constellation Cae, shines at apparent magnitude 9.26 and has spectral type F8.
Its spectrum reads F8 — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Trash star 6 EP
HD 31730
RA 74.2144° · Dec -31.2619° · star
Score breakdown
· 2 badgesTrash 15 pts → Common
- Star +3
- Yellow-white F-type star +3
Total score 6
9 more points to reach Common.
Badges
- Star · +3
- Yellow-white F-type star · +3
Trivia
Hard to believe
- True brightness. It pours out about 1.7 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 F8 — 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 9.3 you'll want a small backyard telescope, over in Caelum.
- 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 December — that's when to go looking.
Its true colour
- Its true colour. Measured through blue and visual filters it comes out orange (B−V 1.3) — 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 4100 K, against the Sun's 5778 K.
What's in a name
- Its catalogue. The HD number is from the Henry Draper Catalogue, in which Annie Jump Cannon personally classified the spectra of nearly 400,000 stars — still the largest such feat by one person.
Properties
- absmag
- -10.74
- bv
- 1.313
- constellation
- Cae
- luminosity
- 1721868.575
- mag
- 9.26
- name
- HD 31730
- spect
- F8
How to see it
Look for HD 31730 in the constellation Cae. At apparent magnitude 9.26, a small backyard telescope will bring it into view.
Like any astronomical target, HD 31730 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 31730 is a trash star
HD 31730 scores 6 points on Spacedle's rarity scale, which places it in the trash tier. Another 9 points would lift it into a rarer tier.
That score comes from 2 science badges — Star 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.