8 new super-hot stars
The Royal Astronomical Society, primarily based in London, mentioned this week (January 9, 2023) that astronomers have pinpointed eight of the most popular stars but identified in our universe. Surprisingly, all have surfaces hotter than 100,000 levels Celsius (180,000 F). And the most popular has a floor temperature of 180,000 C! That’s in distinction to our sun, which has a floor temperature of about 5,800 C (10,500 F).
The Month-to-month Notices of the Royal Astronomical Society will publish the brand new work in its February 2023 challenge. You’ll discover the preprint online here.
The astronomers have been utilizing the Southern African Giant Telescope (SALT) to survey helium-rich subdwarf stars. What’s extra, these are sizzling, low-mass stars, thought to have a mass roughly half that of our sun. Additionally, they’re a lot dimmer than common O-type main-sequence stars, that are younger and really huge stars. The truth is, one principle about helium-rich subdwarfs is that – as a substitute of being younger – they’re advanced stars, of a kind referred to as white dwarfs.
They’re white dwarf stars
Finally, our sun will turn out to be a planet-sized white dwarf star, billions of years from now. That’ll be after the sun’s inside thermonuclear furnace consumes the hydrogen within the sun’s core. That’s as a result of helium-rich subdwarfs are thought to have cores of carbon and oxygen, that are by-products of thermonuclear burning. So in these kinds of stars, the core of the star is regarded as surrounded by a shell during which helium (the 2nd-most-complex factor after hydrogen) is burning. And astronomers imagine helium-rich subdwarfs include between 50 to 100% helium, as evidenced by their spectra.
One of many newly recognized super-hot stars is in a spot the place you’ll certainly look forward to finding a white dwarf. It seems to be the central star of a newly found planetary nebula, which is an enormous shell of fuel round an advanced star, shaped from the layers of fuel which have sloughed off the star. This super-hot star’s planetary nebula seems to be a couple of light-year broad.
2 of the 8 are variable stars
Moreover, two of the opposite newly found sizzling stars are pulsating stars, or variable stars.
The astronomers’ assertion defined:
All of those stars are at a sophisticated stage of their life cycle and are approaching the top of their lives as white dwarfs. On account of their extraordinarily excessive temperatures, every of those new discoveries is multiple hundred occasions brighter than the sun, which is taken into account uncommon for white dwarf stars.
Shedding mild on how stars evolve
The actual fact is, white dwarfs are the densest stars in existence that include regular matter. And pre-white dwarfs are a couple of occasions greater and can shrink to turn out to be white dwarfs inside a couple of thousand years.
Simon Jeffery, an astronomer on the Armagh Observatory and Planetarium, who led the analysis, mentioned:
Stars with efficient temperatures of 100,000 levels Celsius or larger are extremely uncommon. It was an actual shock to seek out so many of those stars in our survey. These discoveries will assist to extend our understanding of the late levels of stellar evolution.
Backside line: A global staff of astronomers – utilizing a telescope in South Africa – have found 8 new super-hot stars.
Source: Hot white dwarfs and pre-white dwarfs discovered with SALT