{"id":8593,"date":"2022-10-13T07:12:12","date_gmt":"2022-10-13T11:12:12","guid":{"rendered":"https:\/\/spaceandplanetarynewswire.com\/?p=8593"},"modified":"2022-10-13T07:12:43","modified_gmt":"2022-10-13T11:12:43","slug":"dust-plumes-observed-being-pushed-into-interstellar-space-by-intense-starlight","status":"publish","type":"post","link":"https:\/\/spaceandplanetarynewswire.com\/?p=8593","title":{"rendered":"Dust Plumes Observed Being \u2018Pushed\u2019 into Interstellar Space by Intense Starlight"},"content":{"rendered":"
Near-infrared imagery of WR140\u2019s expanding circumstellar dust structure. > The observing bands (top left), instrument (top right) and orbital phase \u03d5 (bottom right) are labelled in each panel. Coronagraphic (cor.) and aperture masking (mask) images are labelled in parentheses after the observing bands. All other images were observed with the full aperture. The scale bar in each panel indicates 0.3\u2009arcsec (corresponding to 501\u2009AU at a distance of 1.67 kpc). The images are stretched linearly by the following amounts to accentuate the dust structures that are otherwise faint relative to the bright stellar core: \u03d5\u2009=\u20090.077 Kp-band image stretched between 0 and 0.8 relative to the brightest pixel; \u03d5\u2009=\u20090.111 Kp-band image between 0 and 0.5; \u03d5\u2009=\u20090.111 H-band image between 0 and 0.8; \u03d5\u2009=\u20090.592 Lp-band image between 0 and 1.5\u2009\u00d7\u200910\u22123; \u03d5\u2009=\u20090.592 Ms-band image between 1\u2009\u00d7\u200910\u22124 and 5\u2009\u00d7\u200910\u22123. All other images are not stretched.<\/figcaption><\/figure>\n

The results<\/a>, made using infrared images of the binary star system WR140 taken over 16 years, are reported in the journal Nature<\/em>.<\/p>\n

In a complementary study of WR140, published in Nature Astronomy, <\/em>NASA\u2019s James Webb Space Telescope (JWST) was able to see much deeper to snap an image of not just a single accelerating dust plume, but almost 20 of them, nested inside each other like a giant set of onion skins.<\/p>\n

WR140 is comprised of a huge Wolf-Rayet star and an even bigger blue supergiant star, gravitationally bound in an eight-year orbit. This binary star, in the Cygnus constellation, has been monitored for two decades with one of the world\u2019s largest optical telescopes at the Keck Observatory in Hawaii.<\/p>\n

Astronomers have observed directly for the first time how intense light from stars can \u2018push\u2019 matter. Researchers from the universities of Cambridge and Sydney made the observation when tracking a giant plume of dust generated by the violent interactions between two massive stars.<\/figcaption><\/figure>\n

WR140 episodically puffs out plumes of dust stretching thousands of times the distance from the Earth to the Sun. These dust plumes, produced every eight years, give astronomers a unique opportunity to observe how starlight can affect matter.<\/p>\n

It\u2019s known that light carries momentum, exerting a push on matter known as radiation pressure. Astronomers often witness the outcome of this phenomenon in the form of matter coasting at high speed around the cosmos, but it\u2019s been a difficult process to catch in the act. Direct recording of acceleration due to forces other than gravity is rarely witnessed, and never in a stellar environment like this.<\/p>\n

\u201cIt’s hard to see starlight causing acceleration because the force fades with distance, and other forces quickly take over,\u201d said Yinuo Han from Cambridge\u2019s Institute of Astronomy, first author of the Nature<\/em> paper. \u201cTo witness acceleration at the level that it becomes measurable, the material needs to be reasonably close to the star or the source of the radiation pressure needs to be extra strong. WR140 is a binary star whose ferocious radiation field supercharges these effects, placing them within reach of our high-precision data.\u201d<\/p>\n

All stars generate stellar winds, but those from Wolf-Rayet stars can be more like a stellar hurricane. Elements such as carbon in the wind condense out as soot, which remains hot enough to glow bright in the infrared. Like smoke in the wind, this gives telescopes something that can be observed.<\/p>\n

The team used an imaging technology known as interferometry which was able to act like a zoom lens for the 10-metre Keck telescope mirror, enabling the researchers to recover sufficiently sharp images of WR140 for the study.<\/p>\n

Han and his team found that the dust does not stream out from the star with the wind in a hazy ball. Instead, the dust forms where the winds from the two stars collide, on the surface of a cone-shaped shock front between them.<\/p>\n

Because the orbiting binary star is in constant motion, the shock front also rotates. The sooty plume gets wrapped into a spiral, in the same way that droplets form a spiral in a garden sprinkler.<\/p>\n

The researchers found that WR140 has other tricks up its sleeve. The two stars are not on circular but rather elliptical orbits, and dust production turns on and off as the binary nears and departs the point of closest approach. By modelling these effects into the three-dimensional geometry of the dust plume, the astronomers were able to measure to location of dust features in three-dimensional space.<\/p>\n

\u201cLike clockwork, this star puffs out sculpted smoke rings every eight years, with all this wonderful physics written then inflated in the wind like a banner for us to read,\u201d said co-author Professor Peter Tuthill from the University of Sydney. \u201cEight years later as the binary returns in its orbit, another appears the same as the one before, streaming out into space inside the bubble of the previous one, like a set of giant nested Russian dolls.\u201d<\/p>\n

Because the dust produced by this Wolf-Rayet is so predictable and expands to such large distances, it offered the astronomers a unique laboratory to examine the acceleration zone.<\/p>\n

\u201cIn the absence of external forces, each dust spiral should expand at a constant speed,\u201d said Han, who is also a co-author on the JWST paper. \u201cWe were puzzled at first because we could not get our model to fit the observations, until we finally realised that we were seeing something new. The data did not fit because the expansion speed wasn\u2019t constant, but rather that it was accelerating. We\u2019d caught that for the first time on camera.\u201d<\/p>\n

\u201cIn one sense, we always knew this must be the reason for the outflow, but I never dreamed we\u2019d be able to see the physics at work like this,\u201d said Tuthill. \u201cWhen I look at the data now, I see WR140\u2019s plume unfurling a like giant sail made of dust. When it catches the photon wind streaming from the star, like a yacht catching a gust, it makes a sudden leap forward.\u201d<\/p>\n

With JWST now in operation, researchers can learn much more about WR140 and similar systems. \u201cThe Webb telescope offers new extremes of stability and sensitivity,\u201d said Ryan Lau who led the JWST study. \u201cWe\u2019ll now be able to make observations like this much more easily than from the ground, opening a new window into the world of Wolf-Rayet physics.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

The results, made using infrared images of the binary star system WR140 taken over 16 years, are reported in the journal Nature. In a complementary study of WR140, published in Nature Astronomy, NASA\u2019s James Webb Space Telescope (JWST) was able to see much deeper to snap an image of not just a single accelerating dust plume, but almost 20…<\/p>\n","protected":false},"author":71,"featured_media":8595,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"fifu_image_url":"https:\/\/media.springernature.com\/full\/springer-static\/image\/art%3A10.1038%2Fs41586-022-05155-5\/MediaObjects\/41586_2022_5155_Fig1_HTML.png?as=webp","fifu_image_alt":"Dust Plumes Observed Being \u2018Pushed\u2019 into Interstellar Space by Intense Starlight","footnotes":""},"categories":[207],"tags":[],"class_list":["post-8593","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research"],"_links":{"self":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/8593","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/users\/71"}],"replies":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=8593"}],"version-history":[{"count":2,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/8593\/revisions"}],"predecessor-version":[{"id":8596,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/posts\/8593\/revisions\/8596"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=\/wp\/v2\/media\/8595"}],"wp:attachment":[{"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=8593"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=8593"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spaceandplanetarynewswire.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=8593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}