Rare variable star 40 EP

HD 198729

RA 313.0898° · Dec -3.2206° · star

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Score breakdown

· 8 badges

40 pts · Rare

Rare 50 pts → Epic

Deep red star +8
Distant (over 1,000 light-years) +6
Giant star +6
Variable star +5
Cool red M-type star +5
Gently variable +4
On the zodiac +3
A named variable star +3

Total score 40

10 more points to reach Epic.

Badges

Variable star · +5
Distant (over 1,000 light-years) · +6
On the zodiac · +3
Cool red M-type star · +5
Giant star · +6
Deep red star · +8
Gently variable · +4
A named variable star · +3

Trivia

What it actually is

Spectral class. Its spectrum reads M4III: — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.
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.

Sense of scale

In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

How to spot it. At magnitude 7.8 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Aquarius.
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 August — that's when to go looking.

Could we get there?

Verdict. Impossible with our current technology — and the next millennium of it.

Properties

absmag: -0.205
bv: 1.547
constellation: Aqr
dist ly: 1325.8375
luminosity: 105.1962
mag: 7.84
name: HD 198729
spect: M4III:
var amplitude: 0.19
var designation: IR
var max: 7.756
var min: 7.946

Nearby objects

About HD 198729

HD 198729 is a rare variable star. It lies about 1,325.8 light-years from Earth, sits in the constellation Aqr, shines at apparent magnitude 7.84 and has spectral type M4III:.

Its spectrum reads M4III: — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HD 198729 in the constellation Aqr. At apparent magnitude 7.84, it is an easy target for binoculars.

Like any astronomical target, HD 198729 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 198729 is a rare variable star

HD 198729 scores 40 points on Spacedle's rarity scale, which places it in the rare tier. Another 10 points would lift it into a rarer tier.

That score comes from 8 science badges — Variable star, Distant (over 1,000 light-years), On the zodiac, Cool red M-type star, Giant star, Deep red 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.