Markeb (Kappa Velorum)
Markeb (Kappa Velorum) is a star in the constellation Vela, magnitude 2.5.
One corner of the False Cross, the star pattern that has led southern navigators astray.
Southern navigators learned to be wary of this part of the sky. Markeb is one of four stars that make up the False Cross, a pattern so like the Southern Cross that mixing them up has caused errors in navigating by the stars. Its name comes from the Arabic markab, “something to ride”, and is spelled Markeb to keep it apart from Markab in Pegasus.
What looks like one blue-white point is really a pair of hot stars, circling each other every 117 days at a little more than the Earth–Sun distance. The brighter one has about 13 times the Sun’s mass and 12 times its width, and shines some 13,000 times more brightly. It is running low on hydrogen in its core and beginning to turn into a subgiant.
Markeb’s light even reveals a passing cloud. Over the years, absorption lines from the gas between us and the star have strengthened and weakened, probably because a small, dense cloud is drifting across our line of sight.
Markeb (Kappa Velorum) is 570 light-years away: the light we see from it set off around 1455, around the time Gutenberg printed his Bible.
Did you know?
- No lightweight partner. The fainter companion has 7.7 times the Sun’s mass and a surface of around 19,000 K — slightly hotter than its brighter partner.
- Two names, one word. Markab and Markeb are the same Arabic word. The IAU approved Markab for Alpha Pegasi in 2016 and Markeb for this star in 2017, keeping the two apart.
- Fifth star of the temple. Chinese astronomers placed Markeb in Tiān Shè, the Celestial Earth God’s Temple, together with Gamma and Delta Velorum. It is known as the temple’s fifth star.
A blue-white star of magnitude 2.5 at one corner of the False Cross, a kite of four stars in Vela and Carina often mistaken for the Southern Cross. Compare the two: the real Cross is smaller and brighter, with Alpha and Beta Centauri pointing to it.
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 35°N and never sets south of 35°S.
At its highest it stands below the horizon from 50°N, below the horizon from 35°N, 35° up from the equator, 70° up from 35°S.
Facts
- Type
- Star
- Constellation
- Vela
- Designations
- Kappa Velorum, κ Vel, HR 3734, HD 81188, HIP 45941
- Magnitude
- 2.5
- Position
- RA 9h 22.1m, Dec −55° 1′ (J2000)
- Spectral type
- B2IV
- Colour
- blue-white (B−V -0.15)
- Distance
- 570 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Markeb (Kappa Velorum) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.