CN Boötis
Am star in the constellation Boötes
From Wikipedia, the free encyclopedia
CN Boötis (HD 124953, HR 5343), or simply CN Boo, is a white-hued variable star in the northern constellation of Boötes. With an apparent magnitude of 5.957, it can be faintly seen from Earth by the naked eye, just south-southeast of the much brighter Arcturus. It is located at a distance of 150.7 light-years (46.2 parsecs) according to Gaia DR3 parallax measurements, and is receding at a radial velocity of 4.69±0.18 km/s. It is a member of the Ursa Major Stream,[9] a group of stars with similar velocities that all formed around 300 million years ago.[10]
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 14h 16m 04.13970s[1] |
| Declination | +18° 54′ 42.4852″[1] |
| Apparent magnitude (V) | 5.96[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | A8V[3] |
| U−B color index | +0.05[4] |
| B−V color index | +0.26[4] |
| Variable type | δ Sct[5] |
| Astrometry | |
| Radial velocity (Rv) | 4.69±0.18[1] km/s |
| Proper motion (μ) | RA: 40.288[1] mas/yr Dec.: -30.863[1] mas/yr |
| Parallax (π) | 21.6479±0.0332 mas[1] |
| Distance | 150.7 ± 0.2 ly (46.19 ± 0.07 pc) |
| Details | |
| CN Boötis | |
| Mass | 1.552±0.122[6] M☉ |
| Radius | 1.603±0.108[6] R☉ |
| Luminosity | 6.80±0.197[6] L☉ |
| Surface gravity (log g) | 4.38[7] cgs |
| Temperature | 7388[7] K |
| Rotational velocity (v sin i) | 82[7] km/s |
| Other designations | |
| AG+19°1338, BD+19°2779, GC 19251, HD 124953, HR 5343, SAO 100949, PPM 130449, TIC 135169898, TYC 1472-1427-1, GSC 01472-01427, 2MASS J14160414+1854426, Gaia DR3 1233902704963092608[8] | |
| Database references | |
| SIMBAD | CN Boo |
It was given its variable star designation, CN Boötis, in 1981.[11] Prior to that it was usually referred to as HR 5343 or HD 124953 in the literature.
Stellar characteristics
CN Boo is a late A-type star with an effective temperature of 7,388 K (7,115 °C; 12,839 °F), and has been classified as either a main-sequence star (spectral type A8V[12]/A9V[13]) or a giant star (spectral type A8III[7][9]). A 2023 estimate places its radius at a modest 1.6 R☉,[6] which seems to suggest the former.
The star has been known to be an Am star since at least 1964,[4] when the Bright Star Catalogue classified it as such. It was first discovered to be a δ Scuti variable in 1979 by Costa et al., with a period of 0.04 days (58 minutes) and an amplitude of 0.03 mag. This went against the notion that main-sequence Am stars do not pulsate, something that was accepted as fact at the time, so the team considered the Am classification to be erroneous.[15] A more recent study, however, accepts CN Boo as a pulsating Am star, since it shows a metal abundance pattern archetypal of Am stars, and has a minimum rotation speed (82 km/s) that allows for diffusion processes that cause Am characteristics.[7]
In 1991, CN Boo was found to be a soft X-ray source,[9] meaning that the X-rays it emits are of lower energies, i.e., longer wavelengths. It radiates energy at a rate of 2×1028 erg/s in X-rays,[13] chiefly at an energy range of below 0.5 keV[9] (wavelength >2.48 nm).
Possible companion
The 1991 edition of the Bright Star Catalogue lists CN Boo as a potential spectroscopic binary.[16] A 2008 study, however, did not detect significant radial velocity variations or any signals of the companion star in the spectrum of CN Boo, meaning that if a secondary star exists, it likely has a flux below 5% that of the primary star.[7]
