The discovery of brown dwarfs is a relatively new field.
In the early 90s of the 20th century, astrophysicists began to propose the possibility of the existence of brown dwarfs.
According to the theory of star formation, if the star is not massive enough to initiate a nuclear fusion reaction (mainly hydrogen fusion), then it will not become a normal star.
This is what we often call brown dwarfs.
Brown dwarf
To find brown dwarfs, astronomers use a variety of scientific methods.
Brown dwarfs have different spectral signatures from stars and planets because of their different physical properties and composition.
The presence of brown dwarfs can be detected by observing the spectrum of celestial objects.
A large-scale sky survey project that systematically observed large areas of the sky.
These surveys use infrared and optical telescopes to detect fainter objects, including brown dwarfs.
By analyzing survey data, astronomers have discovered a number of objects with the characteristics of brown dwarfs.
The discovery of brown dwarfs has also benefited from the observation of nearby galaxies, which can be more easily detected by astronomers by observing galaxies closer to Earth.
Infrared observations are important for detecting brown dwarfs because they have relatively low surface temperatures and are mainly emitted in the infrared band.
By combining observational data from different bands, the properties and characteristics of celestial objects can be more accurately determined, leading to the discovery of brown dwarfs.
The discovery of brown dwarfs is a field that is constantly evolving and progressing.
With the continuous improvement of technology and the increase in observation methods, our understanding of brown dwarfs is also deepening.
A large number of brown dwarfs have been discovered, and there are many more possibilities to be discovered.
The origin of the name brown dwarf dates back to the early 90s of the 20th century, when astronomers began to study celestial bodies between planets and stars.
In astronomy, stars are often named after their spectral type, such as O-type stars, B-type stars, etc. Whereas, planets are named after their planet names or numbers.
Since brown dwarfs are not typical stars, nor are they planets, astronomers need to find a suitable name for this object in between.
At an international astronomy conference in 1995, astronomers proposed the term "brown dwarf" to describe such objects.
The choice of the name "brown dwarf" was based on the description of the characteristics of the brown dwarf.
Brown dwarfs are usually less massive than stars and are unable to sustain nuclear fusion reactions, so they are unable to produce sustained energy through nuclear fusion like stars do.
The "brown" in the term "brown dwarf" refers to the surface color of such objects, which is usually due to their lower temperatures.
Brown dwarfs have a lower surface temperature and are mainly emitted in the infrared band, so they appear a darker color in visible light, similar to brown.
The name "brown dwarf" describes these objects between planets and stars, emphasizing their star-like characteristics and their cooler temperatures and fainter appearance.
The name has gained wide acceptance in the astronomical community and has become a common name for brown dwarfs.
peculiarity
Brown dwarfs usually have masses between planets and stars, about 13 to 80 times the mass of Jupiter.
They are not massive enough to initiate and sustain the hydrogen fusion reaction, which is the main mechanism by which stars produce energy.
The internal structure of brown dwarfs is different from that of stars.
The internal pressure and temperature of the star are enough for the proton fusion reaction to take place, producing energy and maintaining the stability of the star.
Brown dwarfs, on the other hand, are not at enough internal pressure and temperature to initiate a hydrogen fusion reaction, so they release stored energy mainly through contraction.
Brown dwarfs typically have lower surface temperatures, around 500 to 2,500 degrees Celsius.
At lower temperatures, they are dominated by infrared radiation, while radiation is weaker in the visible band.
The spectral characteristics of brown dwarfs differ from those of stars and planets.
Their spectra typically show absorption signatures of water vapor, methane, and other molecules.
These features can be detected and identified by spectral observations of brown dwarfs.
Brown dwarfs mainly release energy in the form of thermal radiation, and their radiation intensity is mainly concentrated in the infrared band.
This makes infrared observation an important means of detecting and studying brown dwarfs.
Brown dwarfs are usually older and can reach billions of years or more.
Their formation and evolution process is similar to that of stars, but they live longer because they do not undergo sustained nuclear fusion reactions.
Brown dwarfs are a class of celestial bodies that sit between planets and stars, with characteristics that fall in between.
Stars or planets?
Stars are one of the most common celestial bodies in the universe and are formed by the collapse of clouds of gas and dust and have a certain mass.
Stars have a wide range of masses, from red dwarfs that are smaller than Jupiter's mass to giant stars that exceed the mass of the Sun by tens of times.
Based on the spectral characteristics of a star, information such as its temperature, chemical composition, age, etc., can be determined.
The spectrum of stars is usually divided into several main types, such as O, B, A, F, G, K, and M type stars, arranged from high to low according to temperature.
The brightness of a star depends on its surface temperature and radius and can be expressed in terms of absolute magnitude or apparent magnitude.
The evolutionary process of a star depends on its mass, with smaller stars, such as red dwarfs, lasting longer periods of time, while larger stars burn faster and have shorter lifespans.
Striking a balance between gravity and nuclear reactions inside a star is key to the star's steady state.
Gravity tries to shrink the material inside the star inward, while the nuclear reaction counteracts the effect of gravity by releasing energy, keeping the star stable.
Planets are also celestial bodies in the solar system, and their characteristics are different from those of stars.
Planets are celestial bodies that revolve around the Sun, and they move around the Sun in elliptical orbits, following Kepler's laws.
The orbits of planets usually take on a flatter shape, approaching a plane.
Planets are usually nearly spherical in shape because their own gravitational pull pulls the matter towards the center, making it as close to spherical as possible.
Planets vary in size, from smaller terrestrial planets such as Earth and Hydraureus to huge gas giants such as Jupiter and Saturn.
Most planets have atmospheres that contain a variety of gases and chemical components.
A planet's atmosphere can be studied through observations and detectors, providing information about the planet's composition, climate, and other characteristics.
Many planets have moons that revolve around the planets and move around the sun with the planets.
Based on their characteristics and composition, planets can be divided into terrestrial planets (such as Earth, Mercury, Mars, and Mercury) and gas giants (such as Jupiter and Saturn).
The planets in the solar system exhibit a rich diversity, with differences in size, mass, composition, orbital characteristics, atmosphere, and surface characteristics.
The characteristics of brown dwarfs are not very suitable for comparison, either with stars or with planets.