概括
月球岩石和尘埃样本显示高基里点 (680-780°C),表明强磁性质. 一些样本显示了稳定的磁化,可能是在显著的古代月球磁场中获得的.
科学领域:
- 地质物理学 地质物理学
- 行星科学 行星科学
- 矿物物理 矿物物理
背景情况:
- 了解月球样本的磁性对于破译月球的热和磁历史至关重要.
- 以前的研究表明,月球岩石中存在磁性,但详细的表征正在进行中.
研究的目的:
- 确定月球岩石和尘埃样本的磁性特性,特别是基里点和残余强度.
- 为了研究这些样本中磁化的稳定性和起源.
主要方法:
- 热磁分析以确定基里点.
- 测量岩石碎片上的残留强度.
- 解磁技术 (粘性和热) 用于评估磁性稳定性.
主要成果:
- 对于岩石和尘埃样本,在680°C和780°C之间观察到明显的基里点.
- 剩余强度在样本之间有显著的差异.
- 两个样本表现出稳定的磁化与高残余强制性 (>50 oersteds).
- 部分热去磁化建议在超过1500的磁场中获得.
结论:
- 月球样本具有高温磁相,与含铁矿物相一致.
- 稳定的磁化存在表明过去的月球磁场强度相当大.
- 这些发现有助于早期月球动力发电机和热进化的模型.
相关概念视频
Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
Magnetic Fields
A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...
A magnetic field is defined by the force that a charged particle experiences...
Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Magnetism
Magnets are commonly found in everyday objects, such as toys, hangers, elevators, doorbells, and computer devices. Experimentation on these magnets shows that all magnets have two poles: one is labeled north (N) and the other south (S). Magnetic poles repel if they are alike and attract if unlike. Moreover, both poles of a magnet attract unmagnetized pieces of iron.
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
Magnetic Moment of an Electron
Electrons revolving around a nucleus are analogous to a circular current carrying loop. This current produces a magnetic dipole moment proportional to the electron's orbital angular momentum. Since the orbital angular momentum is quantized in terms of the reduced Planck's constant, the dipole moment is quantized in the Bohr Magneton. The value of the Bohr magneton is 9.27 x 10-24 Am2. Electrons also have an intrinsic spin angular momentum, and the associated spin magnetic moment is...
Potential Due to a Magnetized Object
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...


