Common variable star 17 EP

HIP 97991

RA 298.7200° · Dec 12.7662° · star

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Score breakdown

· 4 badges

17 pts · Common

Common 22 pts → Uncommon

Variable star +5
White A-type star +5
Gently variable +4
A named variable star +3

Total score 17

5 more points to reach Uncommon.

Badges

Variable star · +5
White A-type star · +5
Gently variable · +4
A named variable star · +3

Trivia

Hard to believe

True brightness. It pours out about 413 thousand 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 A2 — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.
It changes. This star does not hold still: its brightness rises and falls on a rhythm of hours, days or years, either pulsing in size or being eclipsed by a companion.

Find it in the sky

How to spot it. At magnitude 10.8 you'll want a small backyard telescope, over in Aquila.
Northern sky. It rides the northern half of the sky — an easier target the further north you are.
Best time of year. It stands highest in the middle of the night around July — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out orange (B−V 0.8) — 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.

Properties

absmag: -9.21
bv: 0.837
constellation: Aql
luminosity: 420726.6284
mag: 10.79
name: HIP 97991
spect: A2
var amplitude: 0.29
var designation: V1165
var max: 10.598
var min: 10.888

Nearby objects

About HIP 97991

HIP 97991 is a common variable star. It sits in the constellation Aql, shines at apparent magnitude 10.79 and has spectral type A2.

Its spectrum reads A2 — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

How to see it

Look for HIP 97991 in the constellation Aql. At apparent magnitude 10.79, a small backyard telescope will bring it into view.

Like any astronomical target, HIP 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 HIP 97991 is a common variable star

HIP 97991 scores 17 points on Spacedle's rarity scale, which places it in the common tier. Another 5 points would lift it into a rarer tier.

That score comes from 4 science badges — Variable star, White A-type star, Gently variable and A named variable 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.