Sigma-1 Cancri, a white main-sequence star in Cancer
Sigma-1 Cancri is a white main-sequence star in the constellation Cancer. At 221 light years away, it shines at an apparent visual magnitude of 5.66.
Sigma-1 Cancri (HIP 43584)
Sigma-1 Cancri is a white main-sequence star in the constellation Cancer. At 221 light years away, it shines at an apparent visual magnitude of 5.66. It is moving through the Galaxy at a speed of 12.5 km/s relative to the Sun.
Sky position: RA 8h 52.6m, Dec +32° 28.4'
Common designations: Sigma-1 Cancri, 51 Cancri, HR 3519, HD 75698, HIP 43584, Gaia DR3 712988829111292672
Sigma-1 Cancri has the spectral type A8Vam. A-type stars are white stars with surface temperatures of roughly 7,500 to 10,000 K. Their spectra are dominated by strong hydrogen lines, and many of them rotate rapidly. Its luminosity class V means it is a main-sequence (dwarf) star, still fusing hydrogen into helium in its core like the Sun.
How to find Sigma-1 Cancri in the sky
Sigma-1 Cancri lies in Cancer. With a declination of +32° 28.4', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 58° S. Observers poleward of latitude 58° N see it as circumpolar: it never sets. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around February, which makes the weeks around that month the best time to observe it.
Tabulated data for Sigma-1 Cancri
Astrometry and spectroscopy
| Right Ascension (J2000) | 133.14425828° (8h 52.6m) |
| Declination (J2000) | 32.47415912° (+32° 28.4') |
| Galactic Longitude | 191.64385717° |
| Galactic Latitude | 38.56965851° |
| Proper motion RA | -5.60 mas/yr |
| Proper motion Dec | 15.83 mas/yr |
| Parallax | 14.73 ± 0.10 mas |
| Spectral Type | A8Vam |
| Radial Velocity | -11.26 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| B | 5.87 | 1.71 |
| V | 5.66 | 1.50 |
| J | 5.48 | 1.32 |
| H | 5.19 | 1.03 |
| K | 5.15 | 0.99 |
Colour index B-V: +0.21
Derivations
- Heliocentric distance: 67.89 pc (221 light years) (0.7% margin of error)
- Absolute visual magnitude: 1.50
- Transverse velocity: 5.4 km/s
- Space velocity relative to the Sun: 12.5 km/s
- Galactic position (X, Y, Z): -52.0 pc, -10.7 pc, 42.3 pc
- Galactic velocity (U, V, W): 7.0 km/s, 6.9 km/s, -7.7 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.