Star Stars · In Lupus
KeKouan
KeKouan, β Lupi, is a blue-white giant in Lupus: the 112th brightest star in the night sky.
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- Constellation
- Lupus
- Designation
- β Lupi
- Apparent magnitude
- 2.68 · 112th brightest star in the night sky
- Spectral class
- B2III
- Distance
- 383 light-years
- Highest at midnight
- early May
- Position (J2000)
- RA 14h 59m · Dec −43° 08′
A blue-white giant, around 26,000 K, like Rigel and Spica. About 34× brighter than the faintest star the eye can see. Gives off about 980 times the Sun's visible light. The light you are seeing left around 1643.
When to see it
On the night of Tue 4 May 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | Never rises | ||
| New York EDT | 22:41 | 01:04 · 6° | 03:28 |
| Singapore GMT+8 | 19:21 | 01:15 · 45° | 07:09 |
| Sydney GMT+10 | 15:31 | 00:06 · 81° | 08:41 |
Common questions
- Can I see it from 50° north?
- No. From there it never rises: you would have to travel south of 46° north before it cleared the horizon at all.
- Can I see it from 35° south?
- Yes, and well placed: at its highest it passes almost overhead, 82° up, above most of the air’s haze.
- When is the best time of year to see it?
- Around early May, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by early August it is highest in the early evening, and in early February not until the hours before dawn.
- How far away is it, and how bright?
- It is 383 light-years away, and shines at magnitude 2.68 in our sky. From that far, the Sun would be a star of magnitude 10.2: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.68 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Uridim: KeKouan is 5.2° north-east of it, three fingers at arm’s length.
Look for
From 50° north it never rises; from 35° north it climbs to 12°; from the equator it climbs to 47°; from 35° south it climbs to 82°.
Science
KeKouan’s surface is about 26,000 K, some 20,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 110 nm, in the ultraviolet, past the violet end of what the eye can see, where the Sun’s is strongest at 500 nm. Moved to 33 light-years, the distance astronomers compare stars at, it would shine at magnitude −2.7, brighter than Sirius, the brightest star in our sky.
Did you know
Against Uridim, the brighter star the hop starts from: Uridim looks 1.4 times as bright as KeKouan in our sky; Uridim is 465 light-years away and KeKouan 383 light-years, so side by side Uridim would give off 2.1 times as much light as KeKouan.
Science
KeKouan is the 110th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Leepwal, about 79 light-years from it; on our sky the two are 12° apart.
Look for
The Sun passes 25° north of KeKouan around early November, when it is highest at noon, in daylight: the weeks either side are its worst time of year. From 35° north it is above the horizon for about 7 hours a day and from 35° south about 17. It is 14° from the plane of the Milky Way.