1.3 The Name, Classification and Distribution
15
For the Crab Pulsar, its energy loss rate is about 4.7 × 10
31 W, while the radiating
power of the Crab Nebula is 1.0 × 10
31 W. Apparently, it is shown that the losing
energy of the Crab Pulsar can enough provide the radiation of the Crab Nebula and
itself. Generally, it is speculated that the radiating energy of the single pulsar is
possibly transformed from the rotational energy of itself.
The AP pulsar is a type of neutron star which obtains radiant energy by accreting
material from the companion star in a binary system consisting of a neutron star and
its companion star. Particularly, X-ray binary system is a typical representative of the
type of pulsar. It is different from ordinary radio pulsar that the AP pulsar’s rotation
does not gradually slow down with radiant energy loss other than more and more
rapid. The orbital period in the X-ray binary system is very short, which shows that the
distance between two sub-stars is very near. The pulsar accretes abundant materials
from its companion star, and the materials gathered around the pulsar rapidly falling
onto two poles of the pulsar along the magnetic field lines. And thus, high-energy
radiations including X-rays are generated as the stream of materials continuously
impacts the pulsar’s surface. According to the mass and gravity of the companion
stars, the AP pulsars are also subdivided into two types, High-Mass X-ray Binary
(HMXB) and Low-Mass X-ray Binary (LMXB).
The HMXB is a binary system consisting of a neutron star and a high-mass
companion star, where the neutron star produces X-ray radiation and orbits the
companion star. The companion stars are typically 10−30 solar masses in size.
They are obviously immense in comparison to the neutron stars only with a mass
of 1.44−3.2 solar masses and a typical radius of 10 km. It is similar to the mechanism of forming the solar wind, and an extensive high-energy particle stream can be
produced by the immense companion star. The companion star has much immense
mass and high temperature that the intensity of its stellar wind is far greater than
that of the solar wind. The abundant high-energy material streams carried with the
stellar wind are absorbed and captured as they travel through the gravitational field
of the neutron star, and thus an “atmosphere” around the neutron star will be formed;
the materials are accelerated along the magnetic field lines to impact on the solid
crust of the neutron star; finally, the releasing energy from the impaction are transformed into X-rays radiating. In the process of accreting materials, an accretion disk
will generally be produced around the neutron star by using the materials from the
high-mass companion star.
Alternatively, the LMXB is a binary system with a low-mass companion star,
even less than one solar mass, where a neutron star can inhabit. For the LMXB
system, the intensity of stellar wind from the low-mass companion is so weak that
the stellar wind can not be used to capture the matter from the companion star as
a kind of main approach. Since mass of the neutron star is almost equal to that of
its companion star, the gravitational field around the binary system is controlled by
two components of the system together, and thus an equipotential surface of gravity
similar to the Arabic number “8” shape is produced, which is also called Roche
lobes. The two sub-stars of the LMXB system are located in the centers of two
Roche lobes respectively. The Roche lobes are subdivided into three types: detached
binary, semidetached binary and contact binary. Considered that the neutron star has
15
For the Crab Pulsar, its energy loss rate is about 4.7 × 10
31 W, while the radiating
power of the Crab Nebula is 1.0 × 10
31 W. Apparently, it is shown that the losing
energy of the Crab Pulsar can enough provide the radiation of the Crab Nebula and
itself. Generally, it is speculated that the radiating energy of the single pulsar is
possibly transformed from the rotational energy of itself.
The AP pulsar is a type of neutron star which obtains radiant energy by accreting
material from the companion star in a binary system consisting of a neutron star and
its companion star. Particularly, X-ray binary system is a typical representative of the
type of pulsar. It is different from ordinary radio pulsar that the AP pulsar’s rotation
does not gradually slow down with radiant energy loss other than more and more
rapid. The orbital period in the X-ray binary system is very short, which shows that the
distance between two sub-stars is very near. The pulsar accretes abundant materials
from its companion star, and the materials gathered around the pulsar rapidly falling
onto two poles of the pulsar along the magnetic field lines. And thus, high-energy
radiations including X-rays are generated as the stream of materials continuously
impacts the pulsar’s surface. According to the mass and gravity of the companion
stars, the AP pulsars are also subdivided into two types, High-Mass X-ray Binary
(HMXB) and Low-Mass X-ray Binary (LMXB).
The HMXB is a binary system consisting of a neutron star and a high-mass
companion star, where the neutron star produces X-ray radiation and orbits the
companion star. The companion stars are typically 10−30 solar masses in size.
They are obviously immense in comparison to the neutron stars only with a mass
of 1.44−3.2 solar masses and a typical radius of 10 km. It is similar to the mechanism of forming the solar wind, and an extensive high-energy particle stream can be
produced by the immense companion star. The companion star has much immense
mass and high temperature that the intensity of its stellar wind is far greater than
that of the solar wind. The abundant high-energy material streams carried with the
stellar wind are absorbed and captured as they travel through the gravitational field
of the neutron star, and thus an “atmosphere” around the neutron star will be formed;
the materials are accelerated along the magnetic field lines to impact on the solid
crust of the neutron star; finally, the releasing energy from the impaction are transformed into X-rays radiating. In the process of accreting materials, an accretion disk
will generally be produced around the neutron star by using the materials from the
high-mass companion star.
Alternatively, the LMXB is a binary system with a low-mass companion star,
even less than one solar mass, where a neutron star can inhabit. For the LMXB
system, the intensity of stellar wind from the low-mass companion is so weak that
the stellar wind can not be used to capture the matter from the companion star as
a kind of main approach. Since mass of the neutron star is almost equal to that of
its companion star, the gravitational field around the binary system is controlled by
two components of the system together, and thus an equipotential surface of gravity
similar to the Arabic number “8” shape is produced, which is also called Roche
lobes. The two sub-stars of the LMXB system are located in the centers of two
Roche lobes respectively. The Roche lobes are subdivided into three types: detached
binary, semidetached binary and contact binary. Considered that the neutron star has