Subj : Daily APOD Report To : All From : Ben Ritchey Date : Sun Jul 08 2018 10:18:05 APOD: 2018 July 8 - The Extraordinary Spiral in LL Pegasi Astronomy Picture of the Day Discover the cosmos! [1] Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2018 July 8 [2] The Extraordinary Spiral in LL Pegasi Image Credit: NASA [3] , ESA [4] , Hubble [5] , HLA [6] ; Processing & Copyright: Domingo Pestana [7] & Raul Villaverde [8] Explanation: What created the strange spiral structure on the upper left? No one is sure, although it is likely related to a star in a binary star [9] system entering the planetary nebula [10] phase, when its outer atmosphere is ejected. The huge spiral [11] spans about a third of a light year [12] across and, winding four or five complete turns [13] , has a regularity that is without precedent. Given the expansion rate of the spiral [14] gas, a new layer must appear about every 800 years, a close match to the time it takes for the two stars to orbit each other. The star system [15] that created it is most commonly known as LL Pegasi [16] , but also AFGL 3068. The unusual structure itself has been cataloged as IRAS 23166+1655 [17] . The featured image was taken in near- infrared [18] light by the Hubble Space Telescope [19] . Why the spiral glows [20] is itself a mystery, with a leading hypothesis being illumination by light reflected from nearby stars. Tomorrow's picture: road to mars [21] ------------------------------------------------------------------------------- < [22] | Archive [23] | Submissions [24] | Index [25] | Search [26] | Calendar [27] | RSS [28] | Education [29] | About APOD [30] | Discuss [31] | > [32] ------------------------------------------------------------------------------- Authors & editors: Robert Nemiroff [33] (MTU [34] ) & Jerry Bonnell [35] (UMCP [36] ) NASA Official: Phillip Newman Specific rights apply [37] . NASA Web Privacy Policy and Important Notices [38] A service of: ASD [39] at NASA [40] / GSFC [41] & Michigan Tech. U. [42] ---------- Site notes: [1] archivepix.html [2] image/1807/LLPeg_HubblePestana_2000.jpg [3] https://www.nasa.gov/ [4] http://www.esa.int/ [5] https://www.nasa.gov/mission_pages/hubble/main/index.html [6] https://hla.stsci.edu/ [7] https://www.flickr.com/photos/122467237@N08/ [8] https://www.flickr.com/photos/113243238@N08/ [9] ap970219.html [10] http://en.wikipedia.org/wiki/Planetary_nebula [11] ap151130.html [12] http://chandra.harvard.edu/photo/cosmic_distance.html [13] https://www.eso.org/public/images/potw1710a/ [14] http://en.wikipedia.org/wiki/Spiral [15] https://www.eso.org/public/videos/potw1710a/ [16] http://adsabs.harvard.edu/abs/2012A%26A...544L..18L [17] http://en.wikipedia.org/wiki/IRAS_23166%2B1655 [18] https://science.nasa.gov/ems/07_infraredwaves [19] ap090525.html [20] http://flyingpudding.com/projects/florets/applet/ [21] ap180709.html [22] ap180707.html [23] archivepix.html [24] lib/apsubmit2015.html [25] lib/aptree.html [26] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search [27] calendar/allyears.html [28] /apod.rss [29] lib/edlinks.html [30] lib/about_apod.html [31] http://asterisk.apod.com/discuss_apod.php?date=180708 [32] ap180709.html [33] http://www.phy.mtu.edu/faculty/Nemiroff.html [34] http://www.phy.mtu.edu/ [35] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html [36] http://www.astro.umd.edu/ [37] lib/about_apod.html#srapply [38] https://www.nasa.gov/about/highlights/HP_Privacy.html [39] https://astrophysics.gsfc.nasa.gov/ [40] https://www.nasa.gov/ [41] https://www.nasa.gov/centers/goddard/ [42] http://www.mtu.edu/ --- Mystic BBS v1.12 A39 (Windows/32) * Origin: FIDONet - The Positronium Repository (1:393/68) .