Phact (Alpha Columbae)
Phact (Alpha Columbae) is a star in the constellation Columba, magnitude 2.6.
The Dove’s brightest star — a fast spinner wrapped in a glowing disc of gas.
Phact wears a ring of glowing gas. It is a Be star: a hot B-type star surrounded by a disc of gas whose hydrogen shines in bright emission lines. Like nearly all such stars it spins fast — at least 176 kilometres per second, and perhaps around 457 at its equator.
Its light may also waver by a few hundredths of a magnitude, as Gamma Cassiopeiae — the best-known of these restless, disc-bearing stars — does. That makes it a suspected variable.
The name comes from the Arabic fākhitah, “ring dove”. It was first used for the constellation Cygnus and only later moved to this star — a happy fit, since Columba is the Dove.
Phact (Alpha Columbae) is 260 light-years away: the light we see from it set off around 1765, around the time Charles Messier published his famous catalogue.
Did you know?
- The Grandfather. Chinese astronomers paired Phact with Epsilon Columbae as Zhàng Rén, the Grandfather. The Western name Chang Jin comes from it.
- A companion by chance. A faint star 13.5 arcseconds away makes Phact look double, but it is only an optical companion: Phact itself is believed to be a single star.
A blue-white star of magnitude 2.6, the brightest in Columba, the Dove. Find Arneb, the brightest star of the Hare below Orion, then drop about 16 degrees due south.
When and where to see it
It is best placed in the evening sky around January, when it crosses the meridian at about 10 pm local time (around midnight in December). It can be seen from everywhere south of 56°N and never sets south of 56°S.
At its highest it stands 6° up from 50°N, 21° up from 35°N, 56° up from the equator, 89° up from 35°S.
Facts
- Type
- Star
- Constellation
- Columba
- Designations
- Alpha Columbae, α Col, HR 1956, HD 37795, HIP 26634
- Magnitude
- 2.6
- Position
- RA 5h 39.6m, Dec −34° 4′ (J2000)
- Spectral type
- B9Ve
- Colour
- blue-white (B−V -0.12)
- Distance
- 260 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Phact (Alpha Columbae) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.