| |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h56m 18.40012s[2] |
| Declination | +00° 40′ 13.2733″[2] |
| Apparent magnitude (V) | 5.81 – 5.84[3] |
| Characteristics | |
| Spectral type | B2 IV–V[4] |
| U−B color index | −0.66[5] |
| B−V color index | +0.09[5] |
| Variable type | β Cephei[3] |
| Astrometry | |
| Proper motion (μ) | RA: −4.997±0.038[2] mas/yr Dec.: −0.369±0.038[2] mas/yr |
| Parallax (π) | 3.5446 ± 0.0453 mas[2] |
| Distance | 920 ± 10 ly (282 ± 4 pc) |
| Absolute magnitude (MV) | −2.54[6] |
| Details | |
| Mass | 8.9±0.7[7] M☉ |
| Radius | 4.1±0.2[8] R☉ |
| Luminosity | 3,426[2] L☉ |
| Surface gravity (log g) | 4.00[4] cgs |
| Temperature | 23,000±1,000[4] K |
| Metallicity [Fe/H] | +0.012[2] dex |
| Rotation | 3.638833±0.000003 d[9] |
| Rotational velocity (v sin i) | 60[9] km/s |
| Age | 21[10] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
V2052 Ophiuchi, also known as HR 6684, is a star about 920 light years from Earth in the constellation Ophiuchus.[2] It is a 5th-magnitude star, making it faintly visible to the naked eye of an observer far from city lights. V2052 Ophiuchi is a Beta Cephei variable (β Cep) star, varying slightly in brightness from magnitude 5.81 to 5.84 over a period of about 3.4 hours.[3]
In 1972, Mikolaj Jerzykiewicz announced that HR 6684 is a variable star, based on his observations using the 0.6 meter Air Force Telescope on Mauna Kea. He classified the star as a β Cep variable with period of 0.13989 days, He further noted that if confirmed, it would be the least luminous and shortest period β Cep star known up to that date.[12] Spectroscopic and photometric observations by D. Harold McNamara and Bruce Bills in 1973 confirmed Jerzykiewicz's results.[13] In 1973, HR 6684 was given the variable star designation V2052 Ophiuchi.[14]
In 1994, Henryk Cugier et al. determined that V2052 Ophiuchi pulsated primarily in the fundamental (l=0) radial mode.[15] A much less powerful non-radial pulsation mode was identified in 2003.[8] Ultraviolet observations by the TD-1A satellite show that throughout its pulsation cycle, the temperature of V2052 Ophiuchi varies by 1040±880 K, and its radius changes by 3.1%±0.9%.[5] Observations at the Pic du Midi Observatory showed that V2052 Ophiuchi has a dipole magnetic field, the axis of which is offset from the star's center, and there are helium spots on the surface near the magnetic poles.[9] V2052 Ophiuchi is a type of chemically peculiar star known as a helium-strong star. Its surface is over-abundant in helium, and under-abundant in oxygen, perhaps due to its magnetic field differentially effecting the diffusion of elements in its atmosphere.[8]
