Miaplacidus (Beta Carinae)
Miaplacidus (Beta Carinae) is a star in the constellation Carina, magnitude 1.7.
A bright southern star with a name nobody can quite explain — the leading light of the Diamond Cross.
Nobody is quite sure what Miaplacidus means. The name first appeared on star maps in 1856, in Elijah Burritt’s atlas Geography of the Heavens. The second half looks like Latin placidus, ‘placid’; the 19th-century star-name scholar William Higgins guessed that the first part comes from the Arabic miyāh, ‘waters’. Neither part is certain.
The star itself is a white giant star of about 3.8 solar masses. At around 260 million years old it has used up its core hydrogen and expanded to almost six times the Sun’s width, yet it still spins fast. It shines with about 220 times the Sun’s light from a surface at about 9,150 K. Unlike Vega or Fomalhaut, it shows no sign of a dusty debris disc.
Miaplacidus (Beta Carinae) is 110 light-years away: the light we see from it set off around 1915, 8 years before Edwin Hubble showed that other galaxies exist.
Did you know?
- Halley’s royal oak. Edmond Halley made it the alpha star of Robur Carolinum, Charles’s Oak, a constellation he created to honour King Charles II. The constellation is no longer used.
- The Southern Boat. Chinese astronomers made it the fifth star of Nán Chuán, the Southern Boat, a pattern within Carina, the Keel.
A bright white star in the far southern sky, at the south-western end of the Diamond Cross, a kite of four stars in Carina. Another of its stars, Theta Carinae, sits in the Southern Pleiades cluster — a fine binocular sight.
When and where to see it
It is best placed in the evening sky around March, when it crosses the meridian at about 10 pm local time (around midnight in February). It can be seen from everywhere south of 20°N and never sets south of 20°S.
At its highest it stands below the horizon from 50°N, below the horizon from 35°N, 20° up from the equator, 55° up from 35°S.
Facts
- Type
- Star
- Constellation
- Carina
- Designations
- Beta Carinae, β Car, HR 3685, HD 80007, HIP 45238
- Magnitude
- 1.7
- Position
- RA 9h 13.2m, Dec −69° 43′ (J2000)
- Spectral type
- A1III-
- Colour
- white (B−V 0.00)
- Distance
- 110 light-years
- Discovered
- Naked-eye star of the far southern sky
Open AstroPilot to see when Miaplacidus (Beta Carinae) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.