White Dwarfs: Compact Corpses of Stars
[ad_1]
White dwarfs are dense, dim, stellar corpses — the last observable stage of evolution for low- and medium-mass stars.
Whilst most massive stars will eventually go supernova, a low or medium mass star with a mass less than about 8 times the mass of the sun will eventually become a white dwarf, according to NASA. Approximately 97% of the stars in the Milky Way will eventually become white dwarfs, according to researchers.
Compared to our sun, a white dwarf has a similar carbon and oxygen mass though it is much smaller in size — similar to Earth, according to New Mexico State University (NMSU).
White dwarf temperatures can exceed 100,000 Kelvin according to NASA (that’s about 179,500 degrees Fahrenheit). Despite these sweltering temperatures, white dwarfs have a low luminosity as they’re so small in size according to NMSU.
Related: Red dwarfs: The most common and longest-lived stars
White dwarf formation
Main-sequence stars, including the sun, form from clouds of dust and gas drawn together by gravity. How the stars evolve through their lifetime depends on their mass. The most massive stars, with eight times the mass of the sun or more, will never become white dwarfs. Instead, at the end of their lives, white dwarfs will explode in a violent supernova, leaving behind a neutron star or black hole.
Did you know?
According to NASA, a teaspoon of white dwarf matter would weigh 5.5 tons on Earth — about the same as an elephant!
Smaller stars, however, will take a slightly more sedate path. Low- to medium-mass stars, such as the sun, will eventually swell up into red giants. After that, the stars shed their outer layers into a ring known as a planetary nebula (early observers thought the nebulas resembled planets such as Neptune and Uranus ). The core that is left behind will be a white dwarf, a husk of a star in which no hydrogen fusion occurs.
Smaller stars, such as red dwarfs, don’t make it to the red giant state. They simply burn through all of their hydrogen, ending the process as a dim white dwarf. However, red dwarfs take trillions of years to consume their fuel, far longer than the 13.8-billion-year-old age of the universe, so no red dwarfs have yet become white dwarfs.
White dwarf characteristics
When a star runs out of fuel, it no longer experiences an outward push from the process of fusion and it collapses inward on itself. White dwarfs contain approximately the mass of the sun but have roughly the radius of Earth, according to Cosmos, the astronomy encyclopedia from Swinburne University in Australia. This makes them among the densest objects in space, beaten out only by neutron stars and black holes. According to NASA, the gravity on the surface of a white dwarf is 350,000 times that of gravity on Earth. That means a 150-pound (68-kilogram) person on Earth would weigh 50 million pounds (22.7 million kg) on the surface of a white dwarf.
White dwarfs reach this incredible density because they are collapsed so tightly that their electrons are smashed together, forming what is called “degenerate matter.” The former stars will keep collapsing until the electrons themselves provide enough of an outward-pressing force to halt the crunch. The more mass, the greater the pull inward, so a more massive white dwarf has a smaller radius than its less massive counterpart. Those conditions mean that, after shedding much of its mass during the red giant phase, no white dwarf can exceed 1.4 times the mass of the sun.
When a star swells up to become a red giant, it engulfs its closest planets. But some can still survive. NASA’s Spitzer spacecraft revealed that at least 1 to 3 percent of white dwarf stars have contaminated atmospheres that suggest rocky material has fallen into them.
“In the quest for Earth-like planets, we have now identified numerous systems which are excellent candidates to harbor them,” Jay Farihi, a white dwarf researcher at the University of Leicester in England, told Space.com. “Where they persist as white dwarfs, any terrestrial planets will not be habitable, but may have been sites where life developed during a previous epoch.”
In one exciting case, researchers have observed the rocky material as it falls into the white dwarf.
“It’s exciting and unexpected that we can see this kind of dramatic change on human timescales,” Boris Gänsicke, an astronomer at the University of Warwick in England, told Space.com.
The fate of a white dwarf
Many white dwarfs fade away into relative obscurity, eventually radiating away all of their energy and becoming so-called black dwarfs, but those that share a system with companion stars may suffer a different fate.
If the white dwarf is part of a binary system, it may be able to pull material from its companion onto its surface. Increasing the white dwarf’s mass can have some interesting results.
One possibility is that the added mass could cause it to collapse into a much denser neutron star.
A far more explosive result is the Type 1a supernova. As the white dwarf pulls material from a companion star, the temperature increases, eventually triggering a runaway reaction that detonates in a violent supernova that destroys the white dwarf. This process is known as a “single-degenerate model” of a Type 1a supernova.
Related: Know Your Novas: Star Explosions Explained (Infographic)
In 2012, researchers were able to closely observe the complex shells of gas surrounding one Type 1a supernova in fine detail.
“We really saw, for the first time, detailed evidence of the progenitor for a Type 1a supernova,” Benjamin Dilday, the study’s lead author and an astronomer at Las Cumbres Observatory Global Telescope Network in California told SPACE.com.
If the companion is another white dwarf instead of an active star, the two stellar corpses merge together to kick off the fireworks. This process is known as a “double-degenerate model” of a Type 1a supernova.
At other times, the white dwarf may pull just enough material from its companion to briefly ignite in a nova, a far smaller explosion. Because the white dwarf remains intact, it can repeat the process several times when it reaches that critical point, breathing life back into the dying star over and over again.
“These are the brightest and most frequent stellar eruptions in the galaxy, and they’re often visible to the naked eye,” Przemek Mróz, an astronomer at Poland’s Warsaw University, told Space.com in a previous article.
Additional resources
- Learn more about white dwarfs with ESA.
- Explore the different types of stars with NASA.
- Discover the evolution of binary star systems with the educational site Lumen Learning.
[ad_2]
Original Post
Good write-up, I?¦m normal visitor of one?¦s website, maintain up the excellent operate, and It’s going to be a regular visitor for a lengthy time.
I truly enjoy looking at on this site, it holds superb posts. “Beware lest in your anxiety to avoid war you obtain a master.” by Demosthenes.
Magnificent site. Lots of useful info here. I am sending it to several pals ans also sharing in delicious. And obviously, thank you in your effort!
Good website! I truly love how it is easy on my eyes and the data are well written. I am wondering how I could be notified whenever a new post has been made. I have subscribed to your RSS feed which must do the trick! Have a great day!
Hey, I think your site might be having browser compatibility issues. When I look at your website in Chrome, it looks fine but when opening in Internet Explorer, it has some overlapping. I just wanted to give you a quick heads up! Other then that, great blog!
certainly like your web site but you have to check the spelling on quite a few of your posts. Many of them are rife with spelling issues and I find it very troublesome to tell the truth nevertheless I will definitely come back again.
I think this internet site contains very fantastic pent content material articles.
Hi my family member! I want to say that this article is amazing, nice written and include approximately all significant infos. I’d like to see more posts like this.
I have been examinating out many of your posts and it’s nice stuff. I will make sure to bookmark your blog.
I haven’t checked in here for a while as I thought it was getting boring, but the last few posts are good quality so I guess I will add you back to my daily bloglist. You deserve it my friend 🙂
I truly appreciate this post. I have been looking everywhere for this! Thank goodness I found it on Bing. You’ve made my day! Thank you again
This site is my breathing in, real wonderful design and perfect articles.
Thanks a bunch for sharing this with all of us you really know what you’re talking about! Bookmarked. Please also visit my web site =). We could have a link exchange contract between us!
he blog was how do i say it… relevant, finally something that helped me. Thanks
Outstanding post, you have pointed out some great details , I likewise conceive this s a very wonderful website.
There is obviously a bunch to know about this. I believe you made various nice points in features also.
Appreciating the hard work you put into your website and in depth information you present. It’s good to come across a blog every once in a while that isn’t the same outdated rehashed material. Excellent read! I’ve bookmarked your site and I’m adding your RSS feeds to my Google account.
It’s hard to find knowledgeable people on this topic, but you sound like you know what you’re talking about! Thanks
of course like your web site but you need to take a look at the spelling on quite a few of your posts. A number of them are rife with spelling issues and I in finding it very troublesome to tell the reality on the other hand I will certainly come again again.
It is actually a great and helpful piece of information. I am satisfied that you just shared this helpful info with us. Please keep us up to date like this. Thanks for sharing.
Perfectly composed written content, Really enjoyed examining.
Awesome blog! Do you have any helpful hints for aspiring writers? I’m planning to start my own website soon but I’m a little lost on everything. Would you propose starting with a free platform like WordPress or go for a paid option? There are so many choices out there that I’m totally overwhelmed .. Any recommendations? Thanks a lot!
Very interesting subject, thank you for posting.
What is a Sugar Defender? Sugar Shield could be an affront affectability enhancement product that effectively supports stable blood sugar levels.
I like the efforts you have put in this, thankyou for all the great blog posts.
Its like you read my mind! You appear to know a lot about this, like you wrote the book in it or something. I think that you could do with a few pics to drive the message home a bit, but other than that, this is magnificent blog. A fantastic read. I’ll certainly be back.
Hi! Quick question that’s totally off topic. Do you know how to make your site mobile friendly? My website looks weird when viewing from my iphone. I’m trying to find a template or plugin that might be able to resolve this issue. If you have any suggestions, please share. Many thanks!
My wife and i were quite joyful when Chris could complete his basic research because of the ideas he discovered while using the site. It’s not at all simplistic to just continually be giving away tricks which other people could have been making money from. So we take into account we need you to give thanks to for this. The main explanations you have made, the easy blog menu, the relationships you aid to instill – it is mostly incredible, and it is leading our son and our family know that the concept is pleasurable, which is unbelievably fundamental. Thank you for the whole lot!