Uncommon variable star 26 EP

HD 121815

RA 209.4933° · Dec -4.3861° · star

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Score breakdown

· 6 badges

26 pts · Uncommon

Uncommon 34 pts → Rare

Deep red star +8
Variable star +5
Gently variable +4
On the zodiac +3
Orange K-type star +3
A named variable star +3

Total score 26

8 more points to reach Rare.

Badges

Variable star · +5
On the zodiac · +3
Orange K-type star · +3
Deep red star · +8
Gently variable · +4
A named variable star · +3

Trivia

Hard to believe

True brightness. It pours out about 3 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 K5 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.
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 8.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Virgo.
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 April — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out deep orange-red (B−V 1.6) — one of the coolest surfaces a star can have while still fusing.

By the numbers

Surface temperature. Its colour puts the surface at roughly 3650 K, against the Sun's 5778 K.

Properties

absmag: -11.35
bv: 1.596
constellation: Vir
luminosity: 3019951.7204
mag: 8.65
name: HD 121815
spect: K5
var amplitude: 0.1
var designation: MP
var max: 8.607
var min: 8.707

Nearby objects

About HD 121815

HD 121815 is an uncommon variable star. It sits in the constellation Vir, shines at apparent magnitude 8.65 and has spectral type K5.

Its spectrum reads K5 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

How to see it

Look for HD 121815 in the constellation Vir. At apparent magnitude 8.65, it is an easy target for binoculars.

Like any astronomical target, HD 121815 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 121815 is an uncommon variable star

HD 121815 scores 26 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 8 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, On the zodiac, Orange K-type 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.