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Rare variable star 43 EP

HD 99619

RA 171.7486° · Dec -61.3693° · star

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Score breakdown

· 6 badges
43 pts · Rare
Rare 50 pts → Epic
  • Supergiant +18
  • Deep red star +8
  • Variable star +5
  • Cool red M-type star +5
  • Gently variable +4
  • A named variable star +3
Total score 43

7 more points to reach Epic.

Badges

  • Variable star · +5
  • Cool red M-type star · +5
  • Supergiant · +18
  • Deep red star · +8
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads M2Ib-II — 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 supergiant, hundreds of times wider than the Sun.
  • 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 6.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Centaurus.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • 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 deep orange-red (B−V 2) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3190 K, against the Sun's 5778 K.

Properties

absmag
-13.28
bv
1.983
constellation
Cen
luminosity
17864875.7485
mag
6.72
name
HD 99619
spect
M2Ib-II
var amplitude
0.32
var designation
V771
var max
6.605
var min
6.925

About HD 99619

HD 99619 is a rare variable star. It sits in the constellation Cen, shines at apparent magnitude 6.72 and has spectral type M2Ib-II.

Its spectrum reads M2Ib-II — 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 99619 in the constellation Cen. At apparent magnitude 6.72, it is an easy target for binoculars.

Like any astronomical target, HD 99619 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 99619 is a rare variable star

HD 99619 scores 43 points on Spacedle's rarity scale, which places it in the rare tier. Another 7 points would lift it into a rarer tier.

That score comes from 6 science badges — Variable star, Cool red M-type star, Supergiant, 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.