| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08h40m 52.125s[2] |
| Declination | +09° 49′ 27.15″[2] |
| Apparent magnitude (V) | 7.18 to 7.91[3] |
| Characteristics | |
| Spectral type | F2 III[4] |
| B−V color index | 0.288±0.020[5] |
| Variable type | δ Sct[3] |
| Astrometry | |
| Radial velocity (Rv) | 25.2±0.4[6] km/s |
| Proper motion (μ) | RA: −29.005 mas/yr[2] Dec.: −15.856 mas/yr[2] |
| Parallax (π) | 4.5062 ± 0.0268 mas[2] |
| Distance | 724 ± 4 ly (222 ± 1 pc) |
| Absolute magnitude (MV) | 1.79[5] |
| Details | |
| Mass | 1.60[7] M☉ |
| Radius | 2.90[8] R☉ |
| Luminosity | 15.96[5] L☉ |
| Surface gravity (log g) | 3.4±0.2[4] cgs |
| Temperature | 6,909±219[7] K |
| Metallicity [Fe/H] | −0.41[7] dex |
| Rotational velocity (v sin i) | 26±1[4] km/s |
| Age | 1.70[7] Gyr |
| Other designations | |
VZ Cnc, BD+10°1848, HD 73857, HIP 42594, SAO 98035, PPM 154840[9] | |
| Database references | |
| SIMBAD | data |
VZ Cancri is a variable star in the constellation Cancer, abbreviated VZ Cnc. It varies in brightness with a period of 0.178364 days, from an apparent visual magnitude of 7.18 down to 7.91,[3] which lies below the typical threshold of visibility for the naked eye. The distance to this star is approximately 724 light years based on parallax measurements,[2] and it is receding from the Sun with a radial velocity of 25 km/s.[6]
This star was discovered to vary in brightness by B. S. Whitney in 1950, and was classified as a cluster-type Cepheid variable,[10]orRR Lyrae star.[11] In 1955, W. S. Fitch found the light curve to be variable and discovered a beat period of 0.716292 d,[12] from which is inferred a second pulsation period of 0.1428041 days.[13] H. A. Abt found that the stellar class of this star varied from A7–A9 III during peak brightness to F1–F2 III at minimum.[14] After H. J. Smith pointed out the distinctiveness of short period RR Lyrae variables in 1956, VZ Cnc has been grouped under the category of Delta Scuti variables.[15]
The star is located near the center of the instability strip.[13] Both pulsation periods for this star are in the first and second overtone;[16] it appears to lack a fundamental mode, possibly as a result of helium depletion in the outer atmosphere.[13] In 1994, an examination of five decades of data on this star suggested a variation in the period of maximum light with a cycle length of 49.3 years.[17] This could be the result of previously undetected pulsation frequencies.[16]
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