Artist’s impression of AR Scorpii. | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Scorpius |
Right ascension | 16h 21m 47.28s [1] |
Declination | −22° 53′ 10.3″ [1] |
Characteristics | |
Apparent magnitude (G) | 13.6 - 16.9 [2] |
White dwarf | |
Evolutionary stage | White dwarf |
Red dwarf | |
Evolutionary stage | Main sequence |
Spectral type | M5 [3] |
Astrometry | |
Proper motion (μ) | RA: 9.707 [4] mas/yr Dec.: −51.469 [4] mas/yr |
Parallax (π) | 8.4918 ± 0.0408 mas [4] |
Distance | 384 ± 2 ly (117.8 ± 0.6 pc) |
Details | |
White dwarf | |
Mass | 0.8 [5] M☉ |
Radius | 0.01 [5] R☉ |
Rotation | 1.95 [3] minutes |
Red dwarf | |
Mass | 0.28 - 0.45 [3] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
AR Scorpii (AR Sco) is a binary pulsar that consists of a white dwarf and a red dwarf. [3] It is located close to the ecliptic plane in the constellation Scorpius. Parallax measurements made by Gaia put the system at a distance of about 380 light-years (120 parsecs). [4]
AR Scorpii is the first "white dwarf-pulsar" to be discovered. [7] Its unusual nature was first noticed by amateur astronomers. [8] The 3.56-hour period in AR Scorpii's light curve caused it to be misclassified as a Delta Scuti variable, but in 2016, this period was found to be the binary orbital period. In addition, the system shows very strong optical, ultraviolet, and radio pulsations originating from the red dwarf with a period of just 1.97 minutes, which is a beat period from the orbital rotation and the white dwarf spin. [3] These pulsations occur when a relativistic beam from the white dwarf sweeps across the red dwarf, which then reprocesses the beam into the observed electromagnetic energy. Although the white dwarf shows evidence of accretion in the past, at present it is not accreting significantly, and the system is powered by the spin-down of the white dwarf. [7] [5] The white dwarf's rotation will slow down on a timescale of 107 years. [5] It has a radius of about 7×103 km, [5] about the same size as Earth.
A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth, and is responsible for the pulsed appearance of emission. Neutron stars are very dense and have short, regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays.
The Crab Pulsar is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054. Discovered in 1968, the pulsar was the first to be connected with a supernova remnant.
Centaurus X-3 is an X-ray pulsar with a period of 4.84 seconds. It was the first X-ray pulsar to be discovered, and the third X-ray source to be discovered in the constellation Centaurus. The system consists of a neutron star orbiting a massive, O-type supergiant star dubbed Krzeminski's star after its discoverer, Wojciech Krzemiński. Matter is being accreted from the star onto the neutron star, resulting in X-ray emission.
The Vela Pulsar is a radio, optical, X-ray- and gamma-emitting pulsar associated with the Vela Supernova Remnant in the constellation of Vela. Its parent Type II supernova exploded approximately 11,000–12,300 years ago.
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WR 86 is a visual binary in the constellation Scorpius consisting of a Wolf-Rayet star and a β Cephei variable. It lies 2° west of NGC 6357 on the edge of the Great Rift in the Milky Way in the tail of the Scorpion.
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