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<\/p>\nNew research from the University of Kansas untangles a decades-old astrophysical puzzle, showing how competing forces \u2014 gravity\u2019s pull and magnetospheric plasma \u2014 split the radio emissions emanating from the Crab Pulsar, the remnant of a supernova observed by ancient astronomers in 1054 CE, into perfectly spaced \u2018stripes.\u2019<\/p>\n
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This composite image shows the Crab Nebula. The Crab pulsar is in the center of the image. Image credit: X-ray \u2013 NASA \/ CXC \/ ASU \/ J. Hester et al.; optical \u2013 NASA \/ HST \/ ASU \/ J. Hester et al.<\/p>\n
In the year 1054 CE, Chinese astronomers were startled by the appearance of a new star, so bright that it was the brightest object in the night sky, second only to the Moon, and was visible in broad daylight for 23 days. The stellar explosion was also recorded by Japanese, Arabic, and Native American stargazers.<\/p>\n
Today, the Crab Nebula<\/a> is visible at the site of that bright star. Also known as Messier 1, M1, NGC 1952 and Taurus A, it lies approximately 6,500 light-years away in the constellation of Taurus.<\/p>\n The Crab Nebula was first identified in 1731 by English doctor, electrical researcher and astronomer John Bevis and was rediscovered in 1758 by French astronomer Charles Messier. It derived its name from its appearance in a drawing made by Irish astronomer Lord Rosse in 1844.<\/p>\n The Crab Pulsar<\/a>, also known as PSR B0531+21, is the central star in the Crab Nebula.<\/p>\n Because it\u2019s nearby and easily observed, study of the Crab Nebula and Crab Pulsar gives astronomers insight into nebulae, supernovae and neutron stars in general.<\/p>\n \u201cGravity changes the shape of spacetime,\u201d said University of Kansas Professor Mikhail Medvedev<\/a>, author of the new study.<\/p>\n \u201cLight doesn\u2019t travel in a straight line in a gravitational field because space itself is curved,\u201d he said.<\/p>\n \u201cWhat would be straight in flat spacetime becomes curved in the presence of strong gravity. In that sense, gravity acts as a lens in curved spacetime.\u201d<\/p>\n While gravitational lensing has been discussed extensively in the context of black holes, this is the only case where astronomers see a \u2018tug-of-war\u2019 between plasma and gravity shaping the observed signal.<\/p>\n \u201cIn black hole images, gravity alone shapes the structure,\u201d Professor Medvedev said.<\/p>\n \u201cIn the Crab Pulsar, both gravity and plasma act together. This represents the first real-world application of this combined effect.\u201d<\/p>\n \u201cThere\u2019s a remarkable pattern in Pulsar\u2019s spectrum,\u201d Professor Medvedev said.<\/p>\n \u201cUnlike ordinary broad spectra \u2014 such as sunlight, which contains a continuous range of colors \u2014 the Crab\u2019s high-frequency inter-pulse shows discrete spectral bands. If it were a rainbow, it\u2019s as if only specific \u2018colors\u2019 appear, with nothing in between.\u201d<\/p>\n This is a mosaic image, one of the largest ever taken by Hubble of the Crab Nebula, a 6-light-year-wide expanding remnant of a star\u2019s supernova explosion. Japanese and Chinese astronomers recorded this violent event nearly 1,000 years ago in 1054, as did, almost certainly, Native Americans. Image credit: NASA \/ ESA \/ J. Hester \/ A. Loll, Arizona State University.<\/p>\n Most pulsar radio emissions are spectrally broader and noisy, not banded so cleanly like the Crab Pulsar.<\/p>\n \u201cThe stripes are absolutely distinct with complete darkness between them,\u201d Professor Medvedev said.<\/p>\n \u201cThere\u2019s a bright band, then nothing, bright band, nothing. No other pulsar shows this kind of striation. That uniqueness made the Crab Pulsar especially interesting \u2014 and challenging \u2014 to understand.\u201d<\/p>\n While earlier model could reproduce stripes, the high contrast of the bands actually observed in the Crab Pulsar couldn\u2019t be accounted for.<\/p>\n Indeed, Professor Medvedev recently determined the Crab Pulsar\u2019s plasma matter causes diffraction in the electromagnetic pulses largely responsible for the neutron star\u2019s singular zebra pattern.<\/p>\n But now he has factored in Einstein\u2019s theory of gravity into the mix, finding it plays a pivotal role in the Crab Pulsar\u2019s zebra pattern.<\/p>\n \u201cThe previous theoretical model could reproduce stripes, but not with the observed contrast. The inclusion of gravity provides the missing piece,\u201d Professor Medvedev said.<\/p>\n \u201cThe plasma in the pulsar\u2019s magnetosphere can be thought of as a lens \u2014 but a defocusing lens. Gravity, by contrast, acts as a focusing lens. Plasma tends to spread light rays apart; gravity pulls them inward. When these two effects are superimposed, there are specific paths where they compensate each other.\u201d<\/p>\n The combination of a defocusing magnetospheric plasma and a focusing gravity create in-phase and out-of-phase interference bands of radio-wave intensity that appear as the Crab Pulsar\u2019s zebra stripes.<\/p>\n \u201cBy symmetry, there are at least two such paths for the light,\u201d Professor Medvedev said.<\/p>\n \u201cWhen two nearly identical paths bring light to the observer, they form an interferometer. The signals combine. At some frequencies, they reinforce each other (in phase), producing bright bands. At others, they cancel (out of phase), producing darkness. That is the essence of the interference pattern.\u201d<\/p>\n \u201cThere appears to be little additional physics required to explain the stripes qualitatively.\u201d<\/p>\n \u201cQuantitatively, there may be refinements. For example, the current treatment includes gravity in a static, lowest-order approximation.\u201d<\/p>\n \u201cThe pulsar is rotating, and including rotational effects could introduce quantitative changes, though not qualitative ones.\u201d<\/p>\n The new study<\/a> will be published in the Journal of Plasma Physics<\/a>.<\/p>\n _____<\/p>\n Mikhail V. Medvedev. 2026. Theory of striped dynamic spectra of the Crab pulsar high-frequency interpulse. Journal of Plasma Physics, in press; arXiv: 2602.16955<\/p>\n","protected":false},"excerpt":{"rendered":"New research from the University of Kansas untangles a decades-old astrophysical puzzle, showing how competing forces \u2014 gravity\u2019s…\n","protected":false},"author":2,"featured_media":325719,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[150861,150862,118413,3226,61,60,25742,13923,26223,37427,59298,40239,82,8881,9315,16338,5885],"class_list":{"0":"post-325718","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-crab-nebula","9":"tag-crab-pulsar","10":"tag-gravitational-lens","11":"tag-gravity","12":"tag-ie","13":"tag-ireland","14":"tag-magnetosphere","15":"tag-nebula","16":"tag-neutron-star","17":"tag-plasma","18":"tag-pulsar","19":"tag-radio-signal","20":"tag-science","21":"tag-spectrum","22":"tag-star","23":"tag-supernova","24":"tag-supernova-remnant"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/325718","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=325718"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/325718\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/325719"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=325718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=325718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=325718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"This](\"https:\/\/www.newsbeep.com\/ie\/wp-content\/uploads\/2026\/03\/image_3794-Interstellar-Iron.jpg\")
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