Star profile
Alpha Ara
Variable starWhat is Alpha Ara
α Arae is a hot, rapidly rotating blue star, famous for being surrounded by an equatorial gaseous disc thrown off by centrifugal force. That hydrogen envelope makes it a classical «Be» star, with brightness that fluctuates as the disc waxes and wanes. It dominates the modest southern constellation of the Altar, marking one of the liveliest nodes of the southern sky.
Where it is and when to see it
Alpha Ara lies in the southern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is June, when it culminates around midnight.
- From London it never rises above the horizon.
- From New York it never rises above the horizon.
- From Sydney it culminates about 74° above the horizon.
It can be seen from anywhere south of 40° N.
It ranks no. 2 in brightness among the 43 stars of Ara in our catalogue. To find it, start from Beta Ara, the brightest: it lies about 6° away (a fist at arm's length covers about 10°).
The light you see today left it about 270 years ago.
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Astronomical data for Alpha Ara
- Constellation
- Ara
- Apparent magnitude
- 2.84
- Distance
- 267.4 light years
- Coordinates (J2000)
- RA 262.960° · Dec -49.876°
- Catalogue
- HIP 85792 · HD 158427
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Other stars in Ara
Ara has 43 stars in Stelvia's catalogue. Here are a few of them.
- Beta Ara2.84
- Zeta Ara3.12
- Gamma Ara3.31
- Delta Ara3.60
- Theta Ara3.65
- Eta Ara3.77
- Epsilon 1 Ara4.06
- Sigma Ara4.56