M106 · Messier 106
| Chinese name | M106 星系 |
|---|---|
| Type | Galaxy |
| Constellation | CVn |
| RA | 12h19m |
| Dec | +47° |
| Apparent magnitude | 8.4ᵐ |
| Hemisphere | Northern |
| Best season | Spring |
| Difficulty | Moderate |
| Focal length | 长焦 1000mm+ |
About
M106 (NGC 4258) lies about 23.5 million light-years away in Canes Venatici and is a spiral galaxy with an active galactic nucleus. Its core hosts a supermassive black hole of about 40 million solar masses, and water megamasers in the surrounding accretion disk let astronomers measure both its distance and black-hole mass with exceptional precision, making M106 a key benchmark for calibrating the cosmic distance scale. The black hole's jets heat gas to produce two distinctive "anomalous arms" seen in Hα and X-rays. Its bright, well-ordered stellar arms, dust lanes, and many small companion galaxies make it a popular long-focal deep-sky subject.