Achernar vs Altair
Absolute magnitude puts a gulf between them, −2.70 for Achernar and +2.21 for Altair. Achernar is a B-type star; Altair is an A-type star in Aquila. Altair trails in apparent brightness at magnitude +0.76 against +0.45, leaving Achernar around 1.3 times the brighter target.
Property comparison
| Property | Achernar | Altair |
|---|---|---|
| Designation | Alp Eri | 53Alp Aql |
| Constellation | N/A | Aquila |
| Spectral Class | Class B — B-type (Blue-White) | Class A — A-type (White) |
| Apparent Magnitude | +0.45 | +0.76 |
| Absolute Magnitude | -2.70 | 2.21 |
| Distance | 139 ly | 16.7 ly |
| Mass | N/A | N/A |
| Radius | N/A | N/A |
| Temperature | N/A | N/A |
| Luminosity | N/A | N/A |
Full data for each star: Achernar · Altair
Key differences
Key Differences
- ◆ Both are among the most rapidly rotating known stars and are significantly oblate as a result.
- ◆ Altair rotates in ~10.4 hours and has been directly imaged to confirm its flattened disk-like shape.
- ◆ Achernar's equatorial diameter is 56% wider than its poles — the most flattened bright star known.
- ◆ Altair is an A-type star; Achernar is a hotter B-type star.
- ◆ Altair is very close at 16.7 light-years; Achernar is 139 light-years away.