42 Capricorni
File:BYCapLightCurve.png A visual band light curve of BY Capricorni, adapted from Henry et al. (1995)[1] | |
| Observation data Epoch J2000 Equinox | |
|---|---|
| Constellation | Capricornus |
| Right ascension | Template:RA[2] |
| Declination | Template:DEC[2] |
| Apparent magnitude (V) | 5.18[3] |
| Characteristics | |
| Spectral type | G1 IV[4] (G1 IV + G2 V)[5] |
| U−B Template:Engvar | +0.20[3] |
| B−V Template:Engvar | +0.65[3] |
| Variable type | RS CVn[5] |
| Astrometry | |
| Radial velocity (Rv) | Script error: No such module "val".[6] km/s |
| Proper motion (μ) | RA: −123.05[2] mas/yr Dec.: −308.50[2] mas/yr |
| Parallax (π) | 30.09±0.32 mas[2] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | +2.73[7] (2.79 + 4.73)[5] |
| Orbit[8] | |
| Period (P) | 13.174 d |
| Eccentricity (e) | Script error: No such module "val". |
| Periastron epoch (T) | 2447863.626 ± 0.027 JD |
| Argument of periastron (ω) (secondary) | Script error: No such module "val".° |
| Semi-amplitude (K1) (primary) | Script error: No such module "val". km/s |
| Semi-amplitude (K2) (secondary) | Script error: No such module "val". km/s |
| Details | |
| 42 Cap A | |
| Mass | 1.09[9] Template:Solar mass |
| Radius | 2.6[5] Template:Solar radius |
| Surface gravity (log g) | 3.76[4] cgs |
| Temperature | 5,634[4] K |
| Metallicity [Fe/H] | −0.10[4] dex |
| Rotational velocity (v sin i) | 5.2[5] km/s |
| Age | 6.7[9] Gyr |
| 42 Cap B | |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Rotational velocity (v sin i) | 4.4[5] km/s |
| Other designations | |
| Template:Odlist[10] | |
| Database references | |
| SIMBAD | data |
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42 Capricorni is a binary star[11] system in the zodiac constellation of Capricornus. It has a combined apparent visual magnitude of 5.18,[3] so it is faintly visible to the naked eye. Its annual parallax shift of 30.09 mas yields a distance estimate of about 108 light years; the system is moving closer to the Sun with a radial velocity of −1.2 km/s.[6] 42 Capricorni is 0.2 degree south of the ecliptic and so is subject to lunar occultations.[12]
In 1995 Gregory W. Henry et al. announced that 42 Capricorni is a variable star, a discovery that was made during a survey of chromospherically active late-type stars using an automated telescope.[13] It was given its variable star designation, BY Capricorni, in the year 2000.[14] The star is an RS Canum Venaticorum variable, indicating the presence of an active chromosphere with star spots.[5]
This is a double-lined close spectroscopic binary with an orbital period of 13.174 days and an eccentricity of 0.18.[8] The binary nature of this system was discovered in 1918 by the English astronomer Joseph Lunt. It has a combined spectrum that matches a stellar classification of G1 IV,[4] with the individual components having estimated classes of G1 V and G2 V. The system is a source of X-ray emission.[15]
References
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