About HD 164491
HD 164491 is an uncommon star. It sits in the constellation Sgr, shines at apparent magnitude 8.7 and has spectral type G8/K0III.
Its spectrum reads G8/K0III — a G-type star: the very same spectral class as our own Sun.
Uncommon star 28 EP
HD 164491
RA 270.5916° · Dec -21.9631° · star
Score breakdown
· 5 badgesUncommon 34 pts → Rare
- Toward the galactic centre +8
- Sun-like G-type star +8
- Giant star +6
- Star +3
- On the zodiac +3
Total score 28
6 more points to reach Rare.
Badges
- Star · +3
- Toward the galactic centre · +8
- On the zodiac · +3
- Sun-like G-type star · +8
- Giant star · +6
Trivia
Hard to believe
- True brightness. It pours out about 2.8 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 G8/K0III — a G-type star: the very same spectral class as our own Sun.
Find it in the sky
- How to spot it. At magnitude 8.7 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 1.2) — 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 4290 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
- -11.3
- bv
- 1.208
- constellation
- Sgr
- luminosity
- 2884031.5031
- mag
- 8.7
- name
- HD 164491
- spect
- G8/K0III
Nearby objects
How to see it
Look for HD 164491 in the constellation Sgr. At apparent magnitude 8.7, it is an easy target for binoculars.
Like any astronomical target, HD 164491 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 164491 is an uncommon star
HD 164491 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 5 science badges — Star, Toward the galactic centre, On the zodiac, Sun-like G-type star and Giant 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.