Mu1 Cancri
Mu1 Cancri, Latinised from μ1 Cancri, is a variable star in the zodiac constellation of Cancer. The name Mu1 comes from the Bayer naming system: the "1" in the name is because (from Earth) it appears to be close to 10 Cancri, or Mu2 Cancri. It is also known by the variable star designation BL Cancri. The star is dimly visible to the naked eye with an apparent visual magnitude that ranges from 5.87 down to 6.07. Parallax measurements put it about 630 light-years (192 parsecs) from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.28. The position of the star near the ecliptic means it is subject to lunar occultations.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08h 06m 18.39542s |
| Declination | +22° 38′ 07.7587″ |
| Apparent magnitude (V) | +5.99 (5.87–6.07) |
| Characteristics | |
| Evolutionary stage | Asymptotic giant branch |
| Spectral type | M3 III |
| B−V color index | +1.66 |
| Variable type | Lb |
| Astrometry | |
| Radial velocity (Rv) | +29.61±0.57 km/s |
| Proper motion (μ) | RA: −5.716 mas/yr Dec.: −9.696 mas/yr |
| Parallax (π) | 5.2029 ± 0.1702 mas |
| Distance | 630 ± 20 ly (192 ± 6 pc) |
| Absolute magnitude (MV) | −0.79 |
| Details | |
| Radius | 56.5+4.8 −5.2 R☉ |
| Luminosity | 565±21 L☉ |
| Temperature | 3,744+186 −150 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
The star Mu1 Cancri is an evolved red giant currently on the asymptotic giant branch with a stellar classification of M3 III. The lack of technetium-99 in the spectrum indicates it has not yet gone through third dredge-up. It is a slow irregular variable with thermal pulsation periods of 22.6, 37.8 and 203.7 days. The star has expanded to 57 times the radius of the Sun and it is radiating 565 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,774 K.