V2052 Ophiuchi
A faint Beta Cephei variable with a helium-strong surface and offset magnetic field.
V2052 Ophiuchi, also cataloged as HR 6684, sits roughly 920 light-years away in the constellation Ophiuchus. At fifth magnitude, it appears as a faint pinpoint to someone far from city lights. This star belongs to the Beta Cephei class of variables, its brightness shifting subtly between magnitudes 5.81 and 5.84 every 3.4 hours.
In 1972, Mikolaj Jerzykiewicz announced the star’s variability after observing it with the 0.6-meter Air Force Telescope on Mauna Kea. He classified it as a β Cep variable with a period of 0.13989 days and noted that, if confirmed, it would be the least luminous and shortest-period β Cep star known at the time. The following year, D. Harold McNamara and Bruce Bills confirmed his findings through spectroscopic and photometric work, and the star received the variable-star designation V2052 Ophiuchi.
By 1994, Henryk Cugier and colleagues determined that V2052 Ophiuchi pulsates mainly in the fundamental radial mode (l=0). A weaker, non-radial pulsation mode was identified in 2003. Ultraviolet data from the TD-1A satellite revealed that the star’s temperature and radius vary throughout its pulsation cycle. Observations at Pic du Midi Observatory detected a dipole magnetic field, with its axis offset from the star’s center, and helium spots near the magnetic poles. V2052 Ophiuchi is a chemically peculiar helium-strong star: its surface is rich in helium but poor in oxygen, likely because its magnetic field alters how elements diffuse through its atmosphere.
- Distance
- about 920 light years
- Constellation
- Ophiuchus
- Apparent magnitude range
- 5.81 to 5.84
- Variability type
- Beta Cephei (β Cep)
- Period
- 0.13989 days (about 3.4 hours)
- Discovery year
- 1972
- Discoverer
- Mikolaj Jerzykiewicz
Lore & Background
In 1972, Mikolaj Jerzykiewicz announced that HR 6684 is a variable star based on observations using the 0.6 meter Air Force Telescope on Mauna Kea. He classified it as a β Cep variable with a period of 0.13989 days, noting that if confirmed, it would be the least luminous and shortest period β Cep star known up to that date. Spectroscopic and photometric observations by D. Harold McNamara and Bruce Bills in 1973 confirmed Jerzykiewicz's results, and later that year the star received the variable star designation V2052 Ophiuchi.
In 1994, Henryk Cugier et al. determined that V2052 Ophiuchi pulsates primarily in the fundamental (l=0) radial mode, with a much less powerful non-radial pulsation mode identified in 2003. Ultraviolet observations by the TD-1A satellite showed that throughout its pulsation cycle, the star's temperature and radius vary. Observations at the Pic du Midi Observatory revealed a dipole magnetic field whose axis is offset from the star's center, and helium spots on the surface near the magnetic poles. The star is a chemically peculiar helium-strong star, with a surface over-abundant in helium and under-abundant in oxygen, possibly due to its magnetic field differentially affecting the diffusion of elements in its atmosphere.
Reader's Guide
V2052 Ophiuchi holds significance as a benchmark for understanding the lower luminosity and shorter period limits of Beta Cephei variables at the time of its discovery. Its confirmation as a β Cep star expanded the known range of these pulsating variables. The star's primary radial pulsation mode, identified in 1994, and its weaker non-radial mode, found in 2003, provide a case study in multiple pulsation mechanisms. The detection of an offset dipole magnetic field and helium spots near the magnetic poles links its chemical peculiarity—helium-strong and oxygen-weak—to magnetic field effects on elemental diffusion. Ultraviolet observations from the TD-1A satellite further characterize its temperature and radius changes during pulsation. As a helium-strong star, V2052 Ophiuchi contributes to the study of chemically peculiar stars and the role of magnetic fields in shaping stellar atmospheres. Its legacy includes being one of the faintest and fastest β Cep variables known, and a key object for investigating the interplay between pulsation, magnetism, and chemical abundance anomalies.
Did You Know?
- V2052 Ophiuchi varies in brightness from magnitude 5.81 to 5.84 over about 3.4 hours.
- It was discovered to be variable in 1972 by Mikolaj Jerzykiewicz using the 0.6 meter Air Force Telescope on Mauna Kea.
- The star has a dipole magnetic field with an axis offset from its center, and helium spots near the magnetic poles.
- Its surface is over-abundant in helium and under-abundant in oxygen, making it a helium-strong chemically peculiar star.
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