About HD 165553
HD 165553 is a rare star. It sits in the constellation Sgr, shines at apparent magnitude 7.67 and has spectral type F8Ib/II.
Its spectrum reads F8Ib/II — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Rare star 35 EP
HD 165553
RA 271.8342° · Dec -21.2016° · star
Score breakdown
· 5 badgesRare 50 pts → Epic
- Supergiant +18
- Toward the galactic centre +8
- Star +3
- On the zodiac +3
- Yellow-white F-type star +3
Total score 35
15 more points to reach Epic.
Badges
- Star · +3
- Toward the galactic centre · +8
- On the zodiac · +3
- Yellow-white F-type star · +3
- Supergiant · +18
Trivia
What it actually is
- Spectral class. Its spectrum reads F8Ib/II — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
- Where it is in life. It is a supergiant, hundreds of times wider than the Sun.
Find it in the sky
- How to spot it. At magnitude 7.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Sagittarius.
- 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 June — 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.
- 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 4770 K, against the Sun's 5778 K.
Properties
- absmag
- -12.33
- bv
- 0.987
- constellation
- Sgr
- luminosity
- 7447319.7391
- mag
- 7.67
- name
- HD 165553
- spect
- F8Ib/II
Nearby objects
How to see it
Look for HD 165553 in the constellation Sgr. At apparent magnitude 7.67, it is an easy target for binoculars.
Like any astronomical target, HD 165553 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 165553 is a rare star
HD 165553 scores 35 points on Spacedle's rarity scale, which places it in the rare tier. Another 15 points would lift it into a rarer tier.
That score comes from 5 science badges — Star, Toward the galactic centre, On the zodiac, 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.