38 Cancri
Star in the constellation Cancer
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38 Cancri is a variable star in the zodiac constellation Cancer, located around 607 light years from the Sun. This object has the variable star designation BT Cancri; 38 Cancri is the Flamsteed designation. It is a member of the Praesepe cluster[10] but is a challenge to view with the naked eye, having an apparent visual magnitude of 6.65.[3] The star is moving closer to the Earth with a heliocentric radial velocity of +32 km/s.[6]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08h 39m 42.65445s[2] |
| Declination | +19° 46′ 42.4386″[2] |
| Apparent magnitude (V) | 6.65[3] |
| Characteristics | |
| Evolutionary stage | subgiant |
| Spectral type | F0 IV[4] |
| B−V color index | 0.248±0.010[3] |
| Variable type | δ Sct[5] |
| Astrometry | |
| Radial velocity (Rv) | +32.0±2.0[6] km/s |
| Proper motion (μ) | RA: −36.879[2] mas/yr Dec.: −13.103[2] mas/yr |
| Parallax (π) | 5.3700±0.0705 mas[2] |
| Distance | 607 ± 8 ly (186 ± 2 pc) |
| Absolute magnitude (MV) | 0.36[3] |
| Details | |
| Mass | 1.786[7] M☉ |
| Radius | 1.834[7] R☉ |
| Luminosity | 59.31[3] L☉ |
| Surface gravity (log g) | 2.92±0.20[8] cgs |
| Temperature | 7300±200[8] K |
| Metallicity [Fe/H] | −0.16±0.10[8] dex |
| Rotation | 0.670 d[7] |
| Rotational velocity (v sin i) | 138.5[7] km/s |
| Other designations | |
| 38 Cnc, BT Cancri, BD+20°2149, HD 73575, HIP 42485, SAO 98006[9] | |
| Database references | |
| SIMBAD | data |
This is an evolving subgiant star with a stellar classification of F0 IV.[4] It was found to be a pulsating variable by Michel Breger in 1970[11] and is classed as a Delta Scuti variable. The star displays a pattern of variation showing up to 22 different frequencies, with three being dominant.[12] The brightness varies by up to 0.07 in magnitude.[5] The star has a magnetic field with a computed longitudinal field strength of −215±149 G.[8] It has 1.8[7] times the mass of the Sun and 1.8[7] times the Sun's radius. The star is radiating 59[3] times the Sun's luminosity from its photosphere at an effective temperature of around 7,300 K.[8]