Dubhe vs Merak
Removing distance from the comparison leaves Dubhe about 3.9 times the more luminous, absolute magnitudes −1.07 and +0.40. Merak is the nearer of the two at 79.7 light-years, while Dubhe lies 123 light-years away, some 1.5 times farther. Spectroscopically Dubhe resolves as an F-type star in Ursa Major and Merak as an A-type star in Ursa Major. Apparent magnitudes of +1.81 and +2.34 place Dubhe some 1.6 times brighter in the sky than Merak.
Property comparison
| Property | Dubhe | Merak |
|---|---|---|
| Ký Hiệu | 50Alp UMa | 48Bet UMa |
| Chòm Sao | Ursa Major | Ursa Major |
| Phân Loại Quang Phổ | Class F — F-type (Yellow-White) | Class A — A-type (White) |
| Cấp Sao Biểu Kiến | +1.81 | +2.34 |
| Cấp Sao Tuyệt Đối | -1.07 | 0.40 |
| Khoảng Cách | 123 ly | 79.7 ly |
| Khối Lượng | N/A | N/A |
| Bán Kính | N/A | N/A |
| Nhiệt Độ | N/A | N/A |
| Độ Sáng | N/A | N/A |
Full data for each star: Dubhe · Merak
Key differences
Key Differences
- ◆ Both form the famous 'pointer stars' of the Big Dipper — drawing a line through them leads to Polaris.
- ◆ Dubhe is a K-type giant at ~123 light-years; Merak is an A-type main-sequence star at ~80 light-years.
- ◆ Merak is a member of the Ursa Major Moving Group and hosts a debris disk; Dubhe is not a member and moves separately.
- ◆ Dubhe has a radius of ~30 R☉, having evolved off the main sequence; Merak remains on the main sequence at ~3 R☉.
- ◆ Despite their pairing in navigation lore, the two stars are at quite different distances and unrelated physically.