Common star 19 EP

HD 97991

RA 169.0488° · Dec -3.4720° · star

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Score breakdown

· 5 badges

19 pts · Common

Common 22 pts → Uncommon

Hot blue B-type star +6
Blue-white star +5
Star +3
On the zodiac +3
Main-sequence star +2

Total score 19

3 more points to reach Uncommon.

Badges

Star · +3
On the zodiac · +3
Hot blue B-type star · +6
Main-sequence star · +2
Blue-white star · +5

Trivia

What it actually is

Spectral class. Its spectrum reads B1V — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.
Where it is in life. It is on the main sequence, quietly fusing hydrogen in its core exactly as the Sun does.

Find it in the sky

How to spot it. At magnitude 7.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Leo.
Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
Best time of year. It stands highest in the middle of the night around March — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out blue-white (B−V -0.2) — the hallmark of a surface far hotter than the Sun's.
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 13830 K, against the Sun's 5778 K.

Properties

absmag: -12.6
bv: -0.21
constellation: Leo
luminosity: 9549925.8602
mag: 7.4
name: HD 97991
spect: B1V

Nearby objects

About HD 97991

HD 97991 is a common star. It sits in the constellation Leo, shines at apparent magnitude 7.4 and has spectral type B1V.

Its spectrum reads B1V — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 97991 in the constellation Leo. At apparent magnitude 7.4, it is an easy target for binoculars.

Like any astronomical target, HD 97991 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 97991 is a common star

HD 97991 scores 19 points on Spacedle's rarity scale, which places it in the common tier. Another 3 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, On the zodiac, Hot blue B-type star, Main-sequence star and Blue-white 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.