Because these stars' energy is spread across such a large area, their surface temperatures are actually relatively cool, reaching only 4,000 to 5,800 degrees Fahrenheit (2,200 to 3,200 degrees Celsius), a little over half as hot as the sun.
Since a red giant star's energy spreads across a larger area, its surface temperatures are cooler, reaching only 2,200 to 3,200 degrees Celsius / 4,000 to 5,800 degrees Fahrenheit, a little over half as hot as our Sun.
All stars with initial masses up to about eight times that of the Sun will eventually become red giants in the later stages of their lives. They start to cool down and lose a large amount of their mass in a steady, dense wind that streams outwards from the star.
Supergiant stars come in two flavors, red and blue. Blue supergiants are usually the hottest stars in the universe. Supergiant stars burn very quickly through their hydrogen supplies, thus the reason why they have short lifespans.
Red giants can swallow up planets as they expand. The Sun will reach its red giant stage in about 5,000 million years time. During this phase, it will probably engulf the inner planets of our Solar System which could include the Earth.
After a massive red giant star ejects its outer layers, its hot inner core is exposed, and it becomes a blue giant star. An object with a mass less than about 8% of the mass of the Sun, but about 10 times greater than that of Jupiter.
In a few billion years, our sun will turn into a red giant. This will scorch life off Earth, but will establish a new habitable zone that could warm Jupiter, Saturn and Neptune.
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ( M ☉)) 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 (4,700 °C; 8,500 °F) or lower.
Red stars are the coolest. Yellow stars are hotter than red stars. White stars are hotter than red and yellow. Blue stars are the hottest stars of all.
A: Roughly 5 billion years from now, the Sun will exhaust the hydrogen fuel in its core and start burning helium, forcing its transition into a red giant star. During this shift, its atmosphere will expand out to somewhere around 1 astronomical unit — the current average Earth-Sun distance.
When the core of the former red giant has exhausted all of its fuel and shed all the gas it can, the remaining dense stellar cinder is called a white dwarf. The white dwarf is considered “dead” because atoms inside of it no longer fuse to give the star energy.
Some of the hottest stars in the Universe are blue giant stars. You see, the color of a star is defined by its temperature; the coolest stars are red, while the hottest ones appear blue.
After another ~5 billion years, it becomes a subgiant, expanding to double its current size. About 2.5 billion years later, it swells into a red giant, fusing helium internally. It will reach ~300 million km in diameter, engulfing Mercury, Venus, and possibly Earth, too.
Red supergiants are rare stars, but they are visible at great distance and are often variable so there are a number of well-known examples: Antares A. Betelgeuse.
The coolest stars are red with surface temperatures of about 3,000ºC. As a star's temperature increases, as a result of there being more gas in the star – and hence more fuel to burn – it becomes hotter. Its colour changes from orange, through yellow, to white.
There are no green stars because the 'black-body spectrum' of stars, which describes the amount of light at each wavelength and depends on temperature, doesn't produce the same spectrum of colours as, for example, a rainbow.
A red dwarf star, the coolest of the stars that can fuse hydrogen, sits at about 3000 C. Lava usually checks in at a temperature somewhere between 700 degrees and 1200 degrees. At its hottest, lava is only half the temperature of the surface of the dimmest stars.
The Wolf-Rayet star WR 102 is the hottest star known, at 210,000 K. In this infrared composite from WISE and Spitzer, it's barely visible, as almost all of its energy is in shorter-wavelength light.
The light they produce wobbles around, making them hard to pin down.
Our sun's death is a long way off — about 4.5 billion years, give or take — but someday it's going to happen, and what then for our solar system?
The red giants' building material points to an ancient age of more than 10 billion years. The stars contain comparatively little iron, an element that in the course of galactic evolution was produced only slowly.
Earth may just outrun the swelling red giant but its proximity, and the resulting rise in temperature, will probably destroy all life on Earth, and possibly the planet itself.
"Given that this system is an analog to our own solar system, it suggests that Jupiter and Saturn might survive the sun's red giant phase, when it runs out of nuclear fuel and self-destructs." Our sun is expected to move through a few phases when it dies.
A red giant's lifespan varies. A red giant can last for a few millennia at the low end or live as long as one billion years. It is estimated that the sun, the star which provides the Earth with its light and heat, will begin the process of becoming a red star in 5 billion years.
The sun has a surface temperature of 5,500 K, typical for a yellow star. Red stars are cooler than the sun, with surface temperatures of 3,500 K for a bright red star and 2,500 K for a dark red star. The hottest stars are blue, with their surface temperatures falling anywhere between 10,000 K and 50,000 K.