 | This article relies largely or entirely on a single source .(May 2023) |
A superwind is an extremely dense wind emanating from asymptotic giant branch stars towards the end of their lives. [1]
| | This article relies largely or entirely on a single source .(May 2023) |
A superwind is an extremely dense wind emanating from asymptotic giant branch stars towards the end of their lives. [1]
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.
Mira variables are a class of pulsating stars characterized by very red colours, pulsation periods longer than 100 days, and amplitudes greater than one magnitude in infrared and 2.5 magnitude at visual wavelengths. They are red giants in the very late stages of stellar evolution, on the asymptotic giant branch (AGB), that will expel their outer envelopes as planetary nebulae and become white dwarfs within a few million years.
The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's. Horizontal-branch stars are powered by helium fusion in the core and by hydrogen fusion in a shell surrounding the core. The onset of core helium fusion at the tip of the red-giant branch causes substantial changes in stellar structure, resulting in an overall reduction in luminosity, some contraction of the stellar envelope, and the surface reaching higher temperatures.
The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) late in their lives.
The red-giant branch (RGB), sometimes called the first giant branch, is the portion of the giant branch before helium ignition occurs in the course of stellar evolution. It is a stage that follows the main sequence for low- to intermediate-mass stars. Red-giant-branch stars have an inert helium core surrounded by a shell of hydrogen fusing via the CNO cycle. They are K- and M-class stars much larger and more luminous than main-sequence stars of the same temperature.
Rho Persei, Latinized from ρ Persei, is a star in the northern constellation of Perseus. It has the traditional name Gorgonea Tertia, being the third member of the quartet called the Gorgonea in reference to the Gorgons from the legend of Perseus. An apparent visual magnitude of +3.39 makes it visible to the naked eye, but a challenge to view from a well-lit urban environment. Based upon parallax measurements, it is located at a distance of roughly 308 light-years (94 pc) from Earth.
Omega Virginis is a solitary star in the zodiac constellation Virgo. It has an apparent visual magnitude of +5.2, which is bright enough to be faintly visible to the naked eye. Based upon an annual stellar parallax shift of 6.56 milliarcseconds, it is located about 500 light years from the Sun.
R Lyrae is a 4th magnitude semiregular variable star in the constellation Lyra, approximately 350 light years away from Earth. It is a red giant star of the spectral type M5III, meaning it has a surface temperature of under 3,500 kelvins. It is much larger and brighter, yet cooler, than the Sun. In the near-infrared J band, it is brighter than the nearby Vega.
S Coronae Borealis is a Mira variable star in the constellation Corona Borealis. Its apparent magnitude varies between 5.3 and 13.6, with a period of 360 days—just under a year. Within the constellation, it lies to the west of Theta Coronae Borealis, and around 1 degree southeast of the eclipsing binary star U Coronae Borealis.
W43A or IRAS 18450-0148 is a late-type star with an envelope of OH/IR type with a magnetically collimated jet. The star is in the early stages of becoming a planetary nebula, a process that will take several thousand years.
HD 202259 is a suspected variable star in the equatorial constellation of Aquarius. With an apparent magnitude of 6.39, according to the Bortle scale it is faintly visible to the naked eye from dark rural skies. It has a stellar classification of M1 III, and is a red giant located along the asymptotic giant branch of the HR diagram. Located about 900 light years away, its radial velocity of −123.5 km/s indicates this is a high-velocity star.
17 Camelopardalis is a single star in the northern circumpolar constellation of Camelopardalis, located roughly 960 light years away from the Sun. It is visible to the naked eye as a faint, red-hued star with an apparent visual magnitude of 5.44. This object is moving closer to the Earth with a heliocentric radial velocity of −20 km/s.
HD 30442 is a solitary star in the northern circumpolar constellation Camelopardalis. It is faintly visible to the naked eye with an apparent magnitude of 5.47 and is estimated to be 403 light years away from the Solar System. The object has a heliocentric radial velocity of −37 km/s, indicating that it is drifting closer.
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around 5,000 K or lower. The appearance of the red giant is from yellow-white to reddish-orange, including the spectral types K and M, sometimes G, but also class S stars and most carbon stars.
V Hydrae is a carbon star in the constellation Hydra. To date perhaps uniquely in our galaxy it has plasma ejections/eruptions on a grand scale every 8.5 years caused by its near, unseen companion in an 8.5 year orbit, inferred by its ultraviolet excess and periastron passage likely through the outer parts of the star itself.
9 Equulei is an M-type star in the constellation Equuleus. It is an asymptotic giant branch (AGB) star, a star that has exhausted its core helium and is now fusing both hydrogen and helium in shells outside the core. It is also a suspected variable star with an amplitude of about 0.05 magnitudes.
1 Lyncis is a single star in the northern constellation of Lynx. It is also known by its variable star designation of UW Lyncis; 1 Lyncis is the Flamsteed designation. This object is visible to the naked eye as a faint, reddish-hued star with an apparent visual magnitude of 4.95. It is moving further from the Earth with a heliocentric radial velocity of 12 km/s.
TU Andromedae is a variable star of the Mira type in the constellation Andromeda. It has a spectral type of M5e and a visual magnitude which varies between extremes of 7.6 and 13.5.
In the field of stellar evolution, a blue loop is a stage in the life of an evolved star where it changes from a cool star to a hotter one before cooling again. The name derives from the shape of the evolutionary track on a Hertzsprung–Russell diagram which forms a loop towards the blue side of the diagram.
IRAS 04509-6922 is a red supergiant star or red hypergiant in the Large Magellanic Cloud. It is one of the largest stars, with a size of nearly 1400 solar radii. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter. This star has a low metallicity. This is a Mira-type variable star currently on the asymptotic giant branch and shrouded in dust. It is pulsating with a period of 1,259±6 d and an amplitude of 0.72±0.04 mag..
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