{"id":143210,"date":"2021-10-26T18:21:15","date_gmt":"2021-10-26T12:51:15","guid":{"rendered":"https:\/\/blog.forumias.com\/?p=143210"},"modified":"2021-10-26T18:21:15","modified_gmt":"2021-10-26T12:51:15","slug":"explained-what-astronomers-learnt-and-didnt-from-seeing-a-white-dwarf-switch-on-and-off","status":"publish","type":"post","link":"https:\/\/forumias.com\/blog\/explained-what-astronomers-learnt-and-didnt-from-seeing-a-white-dwarf-switch-on-and-off\/","title":{"rendered":"Explained: What astronomers learnt, and didn\u2019t, from seeing a white dwarf \u2018switch on and off\u2019"},"content":{"rendered":"\n
What is the News?<\/b><\/h5>\n

An international team has reported a unique phenomenon where they saw the white dwarf losing its brightness in 30 minutes. These gaps in brightness have been previously reported, but the process usually takes place over a period of several days to months.<\/span><\/p>\n

What is a White Dwarf?<\/b><\/h5>\n

White dwarfs are stars that have burned up all of the hydrogen they once used as nuclear fuel.\u00a0<\/span><\/p>\n

A typical white dwarf is half the size of our Sun and has a surface gravity 100,000 times that of Earth<\/span><\/p>\n

Formation of White Dwarf<\/b><\/h5>\n
\"\"
Source: Secrets of the Universe<\/figcaption><\/figure>\n

Main sequence stars <\/span>including the sun are formed from clouds of dust and gas drawn together by gravity. However, once a star runs out of its fuel, it dies and becomes compact. The lifetime of a star depends on its mass.<\/span><\/p>\n

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, they will explode in a violent <\/span>supernova<\/span>, leaving behind a <\/span>neutron star<\/span> or <\/span>black hole<\/span>.<\/span><\/p>\n

Smaller 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. The core that is left behind will be a white dwarf, a husk of a star in which no hydrogen fusion occurs.<\/span><\/p>\n

What is the Switch on and off Phenomena?<\/b><\/p>\n

The white dwarf discussed here is part of a binary system called TW Pictoris, where a star and a white dwarf orbit each other. The two objects are so close to each other that the star transfers material to the white dwarf.<\/span><\/p>\n

As this material approaches the white dwarf it forms an accretion disk or a disk of gas, plasma, and other particles around it.<\/span><\/p>\n

As the accretion disk material slowly sinks closer towards the white dwarf, it generally becomes brighter. <\/span>There are cases when the donor stars stop feeding the white dwarf disk. However, the reasons for this are still not clear.<\/span><\/p>\n

When this happens, the disk is still bright as it \u201cdrains\u201d material that was previously still there. It then takes the disk about 1-2 months to drain most of the material.<\/span><\/p>\n

However, TW Pictoris drop in brightness in 30 mins was totally unexpected, and it may be due to the process called magnetic gating.<\/span>
\n<\/span><\/b><\/p>\n

Note<\/b>: Magnetic gating happens when the magnetic field is spinning so rapidly around the white Dwarf it creates a barrier, disrupting the amount of matter the white dwarf can receive.<\/span><\/p>\n

What is the significance of these findings?<\/b><\/p>\n

This discovery will help us understand the physics behind accretion \u2013 how black holes and neutron stars feed material from their nearby stars.\u00a0<\/span><\/p>\n

Source:<\/b> This post is based on the article <\/span>\u201c<\/b>Explained: What astronomers learnt, and didn\u2019t, from seeing a white dwarf \u2018switch on and off<\/b>\u201d <\/b>published in <\/span>Indian Express <\/b>on <\/span>25th October 2021.<\/b><\/p>\n","protected":false},"excerpt":{"rendered":"

What is the News? An international team has reported a unique phenomenon where they saw the white dwarf losing its brightness in 30 minutes. These gaps in brightness have been previously reported, but the process usually takes place over a period of several days to months. What is a White Dwarf? White dwarfs are stars… Continue reading Explained: What astronomers learnt, and didn\u2019t, from seeing a white dwarf \u2018switch on and off\u2019<\/span><\/a><\/p>\n","protected":false},"author":10317,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"footnotes":""},"categories":[1566,1738,9],"tags":[],"class_list":["post-143210","post","type-post","status-publish","format-standard","hentry","category-daily-factly-articles","category-science-and-technology-daily-factly-articles","category-public","entry"],"jetpack_featured_media_url":"","views":{"total":0,"cached_at":"","cached_date":1701795896},"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts\/143210","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/users\/10317"}],"replies":[{"embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/comments?post=143210"}],"version-history":[{"count":0,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/posts\/143210\/revisions"}],"wp:attachment":[{"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/media?parent=143210"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/categories?post=143210"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/forumias.com\/blog\/wp-json\/wp\/v2\/tags?post=143210"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}