About 25 Sgr
25 Sgr is an uncommon star. It sits in the constellation Sgr, shines at apparent magnitude 6.53 and has spectral type F2II.
Its spectrum reads F2II — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
Uncommon star 29 EP
25 Sgr
RA 278.6365° · Dec -24.2224° · star
Score breakdown
· 5 badgesUncommon 34 pts → Rare
- Bright giant +12
- Toward the galactic centre +8
- Star +3
- On the zodiac +3
- Yellow-white F-type star +3
Total score 29
5 more points to reach Rare.
Badges
- Star · +3
- Toward the galactic centre · +8
- On the zodiac · +3
- Yellow-white F-type star · +3
- Bright giant · +12
Trivia
What it actually is
- Spectral class. Its spectrum reads F2II — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
- Where it is in life. It is a bright giant, well on its way to the largest stars there are.
Find it in the sky
- How to spot it. At magnitude 6.5 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 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 6320 K, against the Sun's 5778 K.
Properties
- absmag
- -13.47
- bv
- 0.515
- constellation
- Sgr
- luminosity
- 21281390.4598
- mag
- 6.53
- name
- 25 Sgr
- spect
- F2II
How to see it
Look for 25 Sgr in the constellation Sgr. At apparent magnitude 6.53, it is an easy target for binoculars.
Like any astronomical target, 25 Sgr 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 25 Sgr is an uncommon star
25 Sgr scores 29 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 5 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 Bright giant — 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.