About HD 105998
HD 105998 is a rare variable star. It sits in the constellation Cru, shines at apparent magnitude 8.44 and has spectral type G0p SB.
Its spectrum reads G0p SB — a G-type star: the very same spectral class as our own Sun.
Rare variable star 34 EP
HD 105998
RA 182.9965° · Dec -58.7835° · star
Score breakdown
· 5 badgesRare 50 pts → Epic
- Strongly variable +10
- Under the Southern Cross +8
- Sun-like G-type star +8
- Variable star +5
- A named variable star +3
Total score 34
16 more points to reach Epic.
Badges
- Variable star · +5
- Under the Southern Cross · +8
- Sun-like G-type star · +8
- Strongly variable · +10
- A named variable star · +3
Trivia
Hard to believe
- True brightness. It pours out about 3.6 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 G0p SB — a G-type star: the very same spectral class as our own 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 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Crux.
- Southern sky. It rides the southern half of the sky — an easier target the further south you are.
- 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 orange (B−V 1.1) — cooler than the Sun, and the kind of star that burns steadily for tens of billions of years.
By the numbers
- Surface temperature. Its colour puts the surface at roughly 4620 K, against the Sun's 5778 K.
Properties
- absmag
- -11.56
- bv
- 1.053
- constellation
- Cru
- luminosity
- 3664375.7465
- mag
- 8.44
- name
- HD 105998
- spect
- G0p SB
- var amplitude
- 0.68
- var designation
- W
- var max
- 8.182
- var min
- 8.862
How to see it
Look for HD 105998 in the constellation Cru. At apparent magnitude 8.44, it is an easy target for binoculars.
Like any astronomical target, HD 105998 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 105998 is a rare variable star
HD 105998 scores 34 points on Spacedle's rarity scale, which places it in the rare tier. Another 16 points would lift it into a rarer tier.
That score comes from 5 science badges — Variable star, Under the Southern Cross, Sun-like G-type star, Strongly 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.