What is a Hypergiant Star?
Supergiant: The name of the star, located at the very top of the Herod. They are one of the most lustrous stars. Their absolute magnitude is brighter than -2. The brightest blue (hot) supergiants seen by the naked eye are Sansu Qi and Tianjin IV, and the brightest red (cold) supergiants are Sansu IV and Xinsu II.
- Supergiants are the most massive stars.
- Supergiants have large luminosity, indicating that their surface area is obviously higher than that of non-supergiants of the same spectral type.
- Supergiants are divided into blue supergiants (type O to A), yellow supergiants (type F to early K), and red supergiants (late K to M)
- The temperature range of supergiants is very wide. The hottest blue supergiants, such as WR25 in the Carina Nebula, have a surface temperature of nearly 50,000K, and the coldest M-type supergiants are mostly located near 3500K. The coldest supergiant known is
- In addition to the typical young giants with huge masses in the traditional sense, there are some small and medium-mass stars that have some properties of supergiants at the end of evolution, so the spectral classification of supergiants is obtained. But in essence, they are two completely different types of stars from typical supergiants. For example, Taurus RV-type variable stars are often classified as yellow to orange bright supergiants, but in fact their brightness is much smaller than that of type Ia yellow supergiants (F8Ia-type Sagitta-1 has more than 80,000 times the sun Brightness, while most of the RV type Taurus stars do not exceed 10,000 times the brightness of the sun), the mass is only 60% of the sun. These stars have a spectrum similar to that of supergiants just because they have evolved to the end and the surface gravity is extremely low. In fact, they used to be ordinary stars similar to the sun.
- Other similar pseudo-supergiants are Virgo W-type variable stars, some extremely inflated long-period variable stars, telescope-type PV variable stars, and North Corona R-type variable stars. Their common feature is low mass, with ages of billions or even tens of billions of years, and they are late stars that will soon evolve into white dwarfs [2] .
The difference between several types of supergiant stars
Supergiant dwarf
- (Dwarf star): A small main sequence star like the sun, if it is a white dwarf, it is the remains of a star like the sun. The brown dwarf does not have enough material for the melting reaction. Originally refers to stars with weaker luminosity, but now specifically refers to stars with a luminosity level of V in the stellar spectral classification, which is equivalent to main sequence stars. Dwarfs with spectral types O, B, and A are called blue dwarfs (such as Weaver One and Sirius), dwarfs with spectral types F and G are called yellow dwarfs (such as the sun), and dwarfs with spectral types K and later It is a red dwarf (such as the second star of South Gate). But white dwarfs, sub-dwarfs, and "black dwarfs" mean otherwise, and are not dwarfs. A class of weakly luminous stars "degenerate dwarfs" whose matter is in a degenerate state are not included in the list.
- "Black dwarf" is a theoretically estimated celestial body. It refers to a celestial body whose mass is roughly a solar mass or less. It is in a cold degenerate state and no longer emits radiant energy. A star that is not large enough (less than about 0.08 solar mass) and has no nuclear energy.
Superstar superstar
- In astronomy, it refers to a star whose luminosity is larger than ordinary stars (main sequence stars) and smaller than supergiant stars.
- Supergiants are the most massive stars, occupying on the Herod
- Superstar (3 photos)
- Stefan-Bozeman's law shows that the surface of a red supergiant has a lower energy per unit area, so the temperature is colder than that of a blue supergiant, so a red supergiant with the same brightness will be more than a blue supergiant. huge. Because their masses are so huge, they only have a short life span of 10 to 50 million years, so they only exist in young cosmic structures, such as open clusters, spiral arms of spiral galaxies, and irregular galaxies.
- It is rare in spiral galaxy nucleus and has not been observed in elliptical galaxies or globular clusters, because these objects are composed of older stars. The spectrum of supergiants occupies all types, from the O-type spectrum of the early blue supergiant to the M-type of the late red supergiant. Sensu Seven, the brightest star in Orion, is a blue-and-white supergiant, and Sensu Four and Scorpio Xinxin 2 are red supergiants.
- The modeling of supergiant models is still an active and difficult area in the research field, for example, the problem of stellar mass loss remains to be solved. The new trends and research methods are not just to model a star, but to model the entire star cluster, and to compare the distribution and changes of supergiants in it, for example, the distribution state in the galaxy Magellanic Cloud. The first star in the universe is considered brighter and larger than the stars that exist in the universe today. These stars are considered to be the third group, and their existence is necessary to explain that in the observation of quasars, only the spectral lines of two elements, hydrogen and helium.
- Most of the predecessors of Type 2 supernovae were considered red supergiants, however, the predecessors of supernova 1987A were blue supergiants. However, he may be a red superstar before the powerful stellar wind blows away several layers of the outer gas shell. Look for <pre> again, of course, the density of neutron stars is large, the formula is (density) = M (mass) / V (volume). The density of neutron stars is 1 billion tons per cubic centimeter, white dwarfs are 1 million tons per cubic centimeter, supergiants are less than one gram per cubic centimeter, and metal gadolinium is 22 grams per cubic centimeter [3] .