{"id":69059,"date":"2016-12-25T18:57:38","date_gmt":"2016-12-25T17:57:38","guid":{"rendered":"http:\/\/www.astb.se\/cassiopeiabloggen\/?p=69059"},"modified":"2016-12-25T22:53:45","modified_gmt":"2016-12-25T21:53:45","slug":"nr-147-2016","status":"publish","type":"post","link":"https:\/\/www.astb.se\/cassiopeiabloggen\/2016\/12\/25\/nr-147-2016\/","title":{"rendered":"Nr 147 2016"},"content":{"rendered":"<h2>\n\t<strong>Mars &quot;spindlar&quot; utmanar<\/strong><br \/>\n<\/h2>\n<p>\n\tMars yta erbjuder m&aring;nga &ouml;verraskningar. En &auml;r &quot;spindlarna&quot;, vars sm&aring; ursprung nu observerats n&auml;ra sydpolen. Dessa geologiska fenomen skapas n&auml;r kanske metertjocka koldioxidlager t&ouml;ar upp och bildar sm&aring; f&ouml;rdjupningar p&aring; planetytan (&quot;throughs), som genom m&auml;rkliga geologiska processer v&auml;xer ut och f&ouml;rgrenar sig. I slutstadiet n&aring;r vi fram till den st&ouml;rre spindelformationen.\n<\/p>\n<p>\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/new_spider2_closeup_repeat_web.gif\"><img decoding=\"async\" alt=\"new_spider2_closeup_repeat_web\" class=\"aligncenter size-full wp-image-69103\" height=\"338\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/new_spider2_closeup_repeat_web.gif\" width=\"602\" \/><\/a>\n<\/p>\n<p style=\"text-align: center;\">\n\t<em>Bildk&auml;lla; NASA\/MRO\/HiRISE<\/em>\n<\/p>\n<p>\n\t<strong>* Bilderna<\/strong> ovan&nbsp; &auml;r 195 m tv&auml;rs&ouml;ver och vi befinner oss p&aring; latituden 70 gr syd p&aring; Mars.\n<\/p>\n<p>\n\t<strong>* Bilderna &auml;r fr&aring;n <\/strong>2009, 2011 och 2015.\n<\/p>\n<p>\n\t<strong>* En teori pratar om<\/strong> att solv&auml;rmen tr&auml;nger igenom lagren av koldioxid ner genom ytan, d&auml;r isen f&ouml;rvandlas till gas, som expanderar och&nbsp; spr&auml;nger sig upp och bildar ett h&aring;l i isen ovanf&ouml;r. Annan gas f&ouml;ljer med upp och tar med sig sand och andra partiklar upp i atmosf&auml;ren, som s&aring; sm&aring;ningom genom Marsvinden&nbsp; l&auml;gger sig i den m&auml;rkkliga fj&auml;derformen.\n<\/p>\n<p>\n\t<strong>* Storlekarna kan r&ouml;ra sig<\/strong> om allt fr&aring;n 10-tals till 100-tals meter, och <a href=\"https:\/\/www.nasa.gov\/feature\/jpl\/small-troughs-growing-on-mars-may-become-spiders\">nu har Mars-forskarna ocks&aring; kunnat se hur processen g&aring;r till med n&aring;gra &aring;rs mellanrum<\/a>. Mars Reconnaissance Orbiter aka MRO och dess kamerasystem kallat&nbsp; High Resolution Imaging Science Experiment (HiRISE) har&nbsp; f&aring;ngat dramat.\n<\/p>\n<p>\n\t<strong>&#39; H&auml;r finns ocks&aring; en<\/strong> koppling till Mars sanddyner.\n<\/p>\n<p>\n\t<strong>* Ytterligare bilddokument fr&aring;n HiRISE<\/strong> visar p&aring; det unika geologiska fenomenet, som bara Mars har (vad vi vet):\n<\/p>\n<p>\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/pia21258_araneiforms-with-fans-e1482687638786.jpg\"><img decoding=\"async\" alt=\"pia21258_araneiforms-with-fans\" class=\"aligncenter size-full wp-image-69108\" height=\"496\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/pia21258_araneiforms-with-fans-e1482687638786.jpg\" width=\"600\" \/><\/a>\n<\/p>\n<p style=\"text-align: center;\">\n\t<em>Bildk&auml;lla: NASA\/JPL-Caltech\/Univ. of Arizona<\/em>\n<\/p>\n<h2>\n\t<strong>Berlinbok tipsar om Wilhelm-Foerster-Sternwarte<\/strong><br \/>\n<\/h2>\n<p>\n\tBerlin f&ouml;rekommer ofta i mina tankar, och senaste tidens h&auml;ndelser&nbsp; beh&ouml;ver jag inte kommentera. Noterar att v&auml;nnen <strong>Trygve B&aring;ng<\/strong> i h&ouml;st kommit med en f&ouml;rn&auml;mlig Berlin-guide, <em>Berlin: Uppt&auml;cktsf&auml;rder i tid och rum<\/em> (ARX F&ouml;rlag).\n<\/p>\n<p>\n\tBoken bjuder p&aring; kort saklig info om det mesta av det b&auml;sta, och kul nog f&ouml;rekommer &auml;ven Wilhelm-Foerster-Sternwarte i boken som ett l&auml;mpligt utflyktsm&aring;l. Jag hade mycket med detta inspirerande folkobservatorium och dess chef att g&ouml;ra p&aring; 60-talet, och en ny&aring;rshelg, d&aring; jag och <strong>Bertil Pettersson<\/strong> (s&aring; sm&aring;ningom astronom i Uppsala)&nbsp; bodde hos goda Berlin-v&auml;nner f&ouml;r att fira en riktig och grundlig berlinsk Sylvester, var vi p&aring; plats och dokumenterade uppf&ouml;randet av det fina planetariumet vid observatoriet.\n<\/p>\n<p>\n\tDetta planetarium kunde 50-&aring;rsjubilera i fjor&#8230;\n<\/p>\n<p>\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/330px-Wilhelm-Foerster-Sternwarte_Berlin_05.jpg\"><img decoding=\"async\" alt=\"330px-wilhelm-foerster-sternwarte_berlin_05\" class=\"aligncenter size-full wp-image-69092\" height=\"213\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/330px-Wilhelm-Foerster-Sternwarte_Berlin_05.jpg\" width=\"330\" srcset=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/330px-Wilhelm-Foerster-Sternwarte_Berlin_05.jpg 330w, https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/330px-Wilhelm-Foerster-Sternwarte_Berlin_05-300x193.jpg 300w, https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/330px-Wilhelm-Foerster-Sternwarte_Berlin_05-200x129.jpg 200w\" sizes=\"(max-width: 330px) 100vw, 330px\" \/><\/a>\n<\/p>\n<p style=\"text-align: center;\">\n\t<em>Flera kupoler ing&aring;r i observatoriets arsenal liksom ett klassiskt Zeiss-planetarium. Bildk&auml;lla: WFS<\/em>\n<\/p>\n<h2>\n\t<strong>Kolstoft runt Nova Del 2013<\/strong><br \/>\n<\/h2>\n<p>\n\tNovan i Delphini\/Delfinen 2013, katalogbetecknad som <b>V339 Delhini<\/b>, kunde l&auml;tt ses f&ouml;r blotta &ouml;gat och i en f&auml;ltkikare. Novan har sen uppt&auml;ckten f&ouml;ljts noga av astronomer, bl a via SOFIA, det flygande infrar&ouml;dk&auml;nsliga teleskopet, varav n&aring;gra nu rapporterar om <a href=\"https:\/\/arxiv.org\/abs\/1612.06241\">det kolrika stoftet (grafit) i skalet runt stj&auml;rnsm&auml;llen.<\/a>\n<\/p>\n<div style=\"position: absolute; left: -99999px;\">\n<div class=\"first-block\">\n<p>\n\t\t\t(Phys.org)&mdash;A team of astronomers led by Aneurin Evans of the Keele University, U.K., has observed the classical nova V339 Delphini (V339 Del for short) and spotted some peculiar changes in its dust shell. These observations could improve our knowledge about dust formation around stellar remnants. The results of the observational campaign are presented in a paper published Dec. 19 on the arXiv pre-print repository.\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<p>\n\t\t\t&nbsp;\n\t\t<\/p>\n<\/p><\/div>\n<section class=\"article-banner first-banner\">\n<div data-google-query-id=\"CO__mcOzj9ECFVMGGQodH_MBZw\" id=\"div-gpt-ad-1449240174198-2\">\n<div id=\"google_ads_iframe_\/4988204\/Phys_Story_InText_Box_0__container__\" style=\"border: 0pt none; display: inline-block; width: 300px; height: 250px;\">\n\t\t\t\t&nbsp;\n\t\t\t<\/div>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<p>\n\t\t\t\t&nbsp;\n\t\t\t<\/p>\n<\/p><\/div>\n<\/section>\n<p>\n\t\tDiscovered in August 2013, V339 Delphini is a bright nova in the constellation Delphinus. It is the first nova that has been observed to synthesize lithium, providing the first direct evidence of the supply of lithium to the interstellar medium by an astronomical object. Interestingly, follow-up observations after the discovery of V339 Delphini showed that one month after its detection, <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust\/\" rel=\"tag\">dust<\/a> formation commenced in this nova.\n\t<\/p>\n<p>\n\t\tTo better understand the dust formation process in V339 Delphini, Evans and his colleagues have analyzed sets of data provided by the Stratospheric Observatory For Infrared Astronomy (SOFIA), the Mt. Abu Infrared Observatory in India, the O&#39;Brien Observatory in Marine on St Croix, Minnesota, NASA&#39;s Infrared Telescope Facility (IRTF), Hawaii, and the Multiple Mirror Telescope (MMT), located on Mt. Hopkins, Arizona.\n\t<\/p>\n<p>\n\t\tThe data collected from over two years of observations allowed the researchers to distinguish an apparent rise and decline of the mass and radius of dust grains around this stellar remnant.\n\t<\/p>\n<p>\n\t\tThe team noted that the rapid <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust+formation\/\" rel=\"tag\">dust formation<\/a> occurs around 34th day of observations and afterward, the infrared emission became dominated by the dust. They also found that the dust is graphitic and its condensation temperature was 1,480 K at that moment.\n\t<\/p>\n<p>\n\t\tAccording to the paper, the dust shell that formed had a mass of about five billionths of the mass of the sun and the grains grew to a dimension of a few micrometers. Next, the size and mass of the grains increased rapidly (while the temperature dropped to about 1,000 K), peaked around 100 days after eruption, and finally declined precipitously after this peak.\n\t<\/p>\n<p>\n\t\t&quot;The mass of dust initially rose as a result of an increase in grain size and\/or number, peaked at about day 100, and then declined precipitously,&quot; the paper reads.\n\t<\/p>\n<p>\n\t\tThe researchers sought the most plausible explanation for the observed rise and fall of V339 Delphini&#39;s dust shell. According to them, this change is most likely caused by charging of dust grains by the X-ray emission.\n\t<\/p>\n<p>\n\t\t&quot;We attribute this to the charging of dust grains by the X-ray emission of V339 Del, causing the grains to shatter due to electrostatic stress,&quot; the astronomers concluded.\n\t<\/p>\n<p>\n\t\tMoreover, the authors of the paper excluded the possibility that the destruction of <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust+grains\/\" rel=\"tag\">dust grains<\/a> could be due to evaporation as the temperature was too low to evaporate these graphitic grains.\n\t<\/p>\n<p>\n\t\t&quot;When the dust mass peaked around day 100, the dust temperature was about 1,000 K and steadily declined thereafter; it seems unlikely, therefore, that below 1,000 K, graphitic grains&mdash;for which the sublimation temperature is more than 1,800 K for carbon-rich environments&mdash; would be subject to evaporation,&quot; the scientists wrote in the paper.\n\t<\/p>\n<p class=\"news-relevant\" itemscope=\"\" itemtype=\"http:\/\/schema.org\/WebPage\">\n\t\t<a href=\"http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#\" id=\"inl-rel-href\"><img decoding=\"async\" alt=\"\" class=\"toolsicon ic-rel\" height=\"16\" src=\"http:\/\/cdn.phys.org\/tmpl\/v5\/img\/1x1.gif\" width=\"14\" \/><\/a> <b>Explore further:<\/b> <a href=\"http:\/\/phys.org\/news\/2016-11-scientists-dusty-globules-crab-nebula.html\" itemprop=\"relatedLink\">Scientists catalog nearly 100 dusty globules in the Crab Nebula<\/a>\n\t<\/p>\n<p>\n\t\t<b>More information:<\/b> Rise and fall of the dust shell of the classical nova V339 Delphini, arXiv:1612.06241 [astro-ph.SR] <a href=\"https:\/\/arxiv.org\/abs\/1612.06241\" target=\"_blank\">arxiv.org\/abs\/1612.06241<\/a>\n\t<\/p>\n<p>\n\t\t<b>Abstract<\/b><br \/>\n\t\tWe present infrared spectroscopy of the classical nova V339 Delphini, obtained over a &sim;2 year period. The infrared emission lines were initially symmetrical, with HWHM velocities of 525 km s&minus;1. In later (t\u227377days, where t is the time from outburst) spectra however, the lines displayed a distinct asymmetry, with a much stronger blue wing, possibly due to obscuration of the receding component by dust. Dust formation commenced at &sim; day 34.75 at a condensation temperature of 1480&plusmn;20K, consistent with graphitic carbon. Thereafter the dust temperature declined with time as Td&prop;t&minus;0.346, also consistent with graphitic carbon. The mass of dust initally rose, as a result of an increase in grain size and\/or number, peaked at &sim; day 100, and then declined precipitously. This decline was most likely caused by grain shattering due to electrostatic stress after the dust was exposed to X-radiation. An Appendix summarises Planck Means for carbon, and the determination of grain mass and radius for a carbon dust shell.\n\t<\/p>\n<p>\n\t\tRead more at: <a href=\"http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#jCp\">http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#jCp<\/a>\n\t<\/p>\n<\/div>\n<div style=\"position: absolute; left: -99999px;\">\n<p>\n\t\tDiscovered in August 2013, V339 Delphini is a bright nova in the constellation Delphinus. It is the first nova that has been observed to synthesize lithium, providing the first direct evidence of the supply of lithium to the interstellar medium by an astronomical object. Interestingly, follow-up observations after the discovery of V339 Delphini showed that one month after its detection, <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust\/\" rel=\"tag\">dust<\/a> formation commenced in this nova.\n\t<\/p>\n<p>\n\t\tTo better understand the dust formation process in V339 Delphini, Evans and his colleagues have analyzed sets of data provided by the Stratospheric Observatory For Infrared Astronomy (SOFIA), the Mt. Abu Infrared Observatory in India, the O&#39;Brien Observatory in Marine on St Croix, Minnesota, NASA&#39;s Infrared Telescope Facility (IRTF), Hawaii, and the Multiple Mirror Telescope (MMT), located on Mt. Hopkins, Arizona.\n\t<\/p>\n<p>\n\t\tThe data collected from over two years of observations allowed the researchers to distinguish an apparent rise and decline of the mass and radius of dust grains around this stellar remnant.\n\t<\/p>\n<p>\n\t\tThe team noted that the rapid <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust+formation\/\" rel=\"tag\">dust formation<\/a> occurs around 34th day of observations and afterward, the infrared emission became dominated by the dust. They also found that the dust is graphitic and its condensation temperature was 1,480 K at that moment.\n\t<\/p>\n<p>\n\t\tAccording to the paper, the dust shell that formed had a mass of about five billionths of the mass of the sun and the grains grew to a dimension of a few micrometers. Next, the size and mass of the grains increased rapidly (while the temperature dropped to about 1,000 K), peaked around 100 days after eruption, and finally declined precipitously after this peak.\n\t<\/p>\n<p>\n\t\t&quot;The mass of dust initially rose as a result of an increase in grain size and\/or number, peaked at about day 100, and then declined precipitously,&quot; the paper reads.\n\t<\/p>\n<p>\n\t\tThe researchers sought the most plausible explanation for the observed rise and fall of V339 Delphini&#39;s dust shell. According to them, this change is most likely caused by charging of dust grains by the X-ray emission.\n\t<\/p>\n<p>\n\t\t&quot;We attribute this to the charging of dust grains by the X-ray emission of V339 Del, causing the grains to shatter due to electrostatic stress,&quot; the astronomers concluded.\n\t<\/p>\n<p>\n\t\tMoreover, the authors of the paper excluded the possibility that the destruction of <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust+grains\/\" rel=\"tag\">dust grains<\/a> could be due to evaporation as the temperature was too low to evaporate these graphitic grains.\n\t<\/p>\n<p>\n\t\t&quot;When the dust mass peaked around day 100, the dust temperature was about 1,000 K and steadily declined thereafter; it seems unlikely, therefore, that below 1,000 K, graphitic grains&mdash;for which the sublimation temperature is more than 1,800 K for carbon-rich environments&mdash; would be subject to evaporation,&quot; the scientists wrote in the paper.\n\t<\/p>\n<p class=\"news-relevant\" itemscope=\"\" itemtype=\"http:\/\/schema.org\/WebPage\">\n\t\t<a href=\"http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#\" id=\"inl-rel-href\"><img decoding=\"async\" alt=\"\" class=\"toolsicon ic-rel\" height=\"16\" src=\"http:\/\/cdn.phys.org\/tmpl\/v5\/img\/1x1.gif\" width=\"14\" \/><\/a> <b>Explore further:<\/b> <a href=\"http:\/\/phys.org\/news\/2016-11-scientists-dusty-globules-crab-nebula.html\" itemprop=\"relatedLink\">Scientists catalog nearly 100 dusty globules in the Crab Nebula<\/a>\n\t<\/p>\n<p>\n\t\t<b>More information:<\/b> Rise and fall of the dust shell of the classical nova V339 Delphini, arXiv:1612.06241 [astro-ph.SR] <a href=\"https:\/\/arxiv.org\/abs\/1612.06241\" target=\"_blank\">arxiv.org\/abs\/1612.06241<\/a>\n\t<\/p>\n<p>\n\t\t<b>Abstract<\/b><br \/>\n\t\tWe present infrared spectroscopy of the classical nova V339 Delphini, obtained over a &sim;2 year period. The infrared emission lines were initially symmetrical, with HWHM velocities of 525 km s&minus;1. In later (t\u227377days, where t is the time from outburst) spectra however, the lines displayed a distinct asymmetry, with a much stronger blue wing, possibly due to obscuration of the receding component by dust. Dust formation commenced at &sim; day 34.75 at a condensation temperature of 1480&plusmn;20K, consistent with graphitic carbon. Thereafter the dust temperature declined with time as Td&prop;t&minus;0.346, also consistent with graphitic carbon. The mass of dust initally rose, as a result of an increase in grain size and\/or number, peaked at &sim; day 100, and then declined precipitously. This decline was most likely caused by grain shattering due to electrostatic stress after the dust was exposed to X-radiation. An Appendix summarises Planck Means for carbon, and the determination of grain mass and radius for a carbon dust shell.\n\t<\/p>\n<p>\n\t\tRead more at: <a href=\"http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#jCp\">http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#jCp<\/a>\n\t<\/p>\n<\/div>\n<div style=\"position: absolute; left: -99999px;\">\n<p>\n\t\tDiscovered in August 2013, V339 Delphini is a bright nova in the constellation Delphinus. It is the first nova that has been observed to synthesize lithium, providing the first direct evidence of the supply of lithium to the interstellar medium by an astronomical object. Interestingly, follow-up observations after the discovery of V339 Delphini showed that one month after its detection, <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust\/\" rel=\"tag\">dust<\/a> formation commenced in this nova.\n\t<\/p>\n<p>\n\t\tTo better understand the dust formation process in V339 Delphini, Evans and his colleagues have analyzed sets of data provided by the Stratospheric Observatory For Infrared Astronomy (SOFIA), the Mt. Abu Infrared Observatory in India, the O&#39;Brien Observatory in Marine on St Croix, Minnesota, NASA&#39;s Infrared Telescope Facility (IRTF), Hawaii, and the Multiple Mirror Telescope (MMT), located on Mt. Hopkins, Arizona.\n\t<\/p>\n<p>\n\t\tThe data collected from over two years of observations allowed the researchers to distinguish an apparent rise and decline of the mass and radius of dust grains around this stellar remnant.\n\t<\/p>\n<p>\n\t\tThe team noted that the rapid <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust+formation\/\" rel=\"tag\">dust formation<\/a> occurs around 34th day of observations and afterward, the infrared emission became dominated by the dust. They also found that the dust is graphitic and its condensation temperature was 1,480 K at that moment.\n\t<\/p>\n<p>\n\t\tAccording to the paper, the dust shell that formed had a mass of about five billionths of the mass of the sun and the grains grew to a dimension of a few micrometers. Next, the size and mass of the grains increased rapidly (while the temperature dropped to about 1,000 K), peaked around 100 days after eruption, and finally declined precipitously after this peak.\n\t<\/p>\n<p>\n\t\t&quot;The mass of dust initially rose as a result of an increase in grain size and\/or number, peaked at about day 100, and then declined precipitously,&quot; the paper reads.\n\t<\/p>\n<p>\n\t\tThe researchers sought the most plausible explanation for the observed rise and fall of V339 Delphini&#39;s dust shell. According to them, this change is most likely caused by charging of dust grains by the X-ray emission.\n\t<\/p>\n<p>\n\t\t&quot;We attribute this to the charging of dust grains by the X-ray emission of V339 Del, causing the grains to shatter due to electrostatic stress,&quot; the astronomers concluded.\n\t<\/p>\n<p>\n\t\tMoreover, the authors of the paper excluded the possibility that the destruction of <a class=\"textTag\" href=\"http:\/\/phys.org\/tags\/dust+grains\/\" rel=\"tag\">dust grains<\/a> could be due to evaporation as the temperature was too low to evaporate these graphitic grains.\n\t<\/p>\n<p>\n\t\t&quot;When the dust mass peaked around day 100, the dust temperature was about 1,000 K and steadily declined thereafter; it seems unlikely, therefore, that below 1,000 K, graphitic grains&mdash;for which the sublimation temperature is more than 1,800 K for carbon-rich environments&mdash; would be subject to evaporation,&quot; the scientists wrote in the paper.\n\t<\/p>\n<p class=\"news-relevant\" itemscope=\"\" itemtype=\"http:\/\/schema.org\/WebPage\">\n\t\t<a href=\"http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#\" id=\"inl-rel-href\"><img decoding=\"async\" alt=\"\" class=\"toolsicon ic-rel\" height=\"16\" src=\"http:\/\/cdn.phys.org\/tmpl\/v5\/img\/1x1.gif\" width=\"14\" \/><\/a> <b>Explore further:<\/b> <a href=\"http:\/\/phys.org\/news\/2016-11-scientists-dusty-globules-crab-nebula.html\" itemprop=\"relatedLink\">Scientists catalog nearly 100 dusty globules in the Crab Nebula<\/a>\n\t<\/p>\n<p>\n\t\t<b>More information:<\/b> Rise and fall of the dust shell of the classical nova V339 Delphini, arXiv:1612.06241 [astro-ph.SR] <a href=\"https:\/\/arxiv.org\/abs\/1612.06241\" target=\"_blank\">arxiv.org\/abs\/1612.06241<\/a>\n\t<\/p>\n<p>\n\t\t<b>Abstract<\/b><br \/>\n\t\tWe present infrared spectroscopy of the classical nova V339 Delphini, obtained over a &sim;2 year period. The infrared emission lines were initially symmetrical, with HWHM velocities of 525 km s&minus;1. In later (t\u227377days, where t is the time from outburst) spectra however, the lines displayed a distinct asymmetry, with a much stronger blue wing, possibly due to obscuration of the receding component by dust. Dust formation commenced at &sim; day 34.75 at a condensation temperature of 1480&plusmn;20K, consistent with graphitic carbon. Thereafter the dust temperature declined with time as Td&prop;t&minus;0.346, also consistent with graphitic carbon. The mass of dust initally rose, as a result of an increase in grain size and\/or number, peaked at &sim; day 100, and then declined precipitously. This decline was most likely caused by grain shattering due to electrostatic stress after the dust was exposed to X-radiation. An Appendix summarises Planck Means for carbon, and the determination of grain mass and radius for a carbon dust shell.\n\t<\/p>\n<p>\n\t\tRead more at: <a href=\"http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#jCp\">http:\/\/phys.org\/news\/2016-12-astronomers-fall-shell-nova-v339.html#jCp<\/a>\n\t<\/p>\n<\/div>\n<h2>\n\t<strong>Vad h&auml;nde 2016?<\/strong><br \/>\n<\/h2>\n<p>\n\tDet b&ouml;rjar bli dags att summera det astronomiska &aring;ret 2016. Alla &auml;r &ouml;verens om att h&ouml;gst p&aring; pallen kommer den defitiva uppt&auml;ckten av gravitationsv&aring;gor. LIGO-teoretikerna l&auml;r ligga bra till f&ouml;r Nobelpriset i fysik 2017.\n<\/p>\n<h2>\n\t<strong>S&aring; skapades &quot;badankan&quot;<\/strong><br \/>\n<\/h2>\n<p>\n\tHur gick det till d&aring; &quot;Rosetta-kometen&quot; aka 67P\/Churyumov-Gerasimenko (67P) bildades och fick sin form a la en badanka? W-bloggen har tidigare synat hur de schweiziska astronomer<span class=\"author\" data-url=\"\/component\/author\/?dkey=10.1051\/0004-6361\/201628964&amp;n=1\" id=\"aa28964-16-author-1\">na <strong>M. Jutzi<\/strong><\/span> och <strong><span class=\"author\" data-url=\"\/component\/author\/?dkey=10.1051\/0004-6361\/201628964&amp;n=2\" id=\"aa28964-16-author-2\">W. Benz<\/span><\/strong> r&auml;knat p&aring; f&ouml;rloppet, som kan t&auml;nkas ha sett ut som nedan. Den illustrationen hade vi inte med f&ouml;rra g&aring;ngen, s&aring; h&auml;r &auml;r den nu:\n<\/p>\n<p>\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/big_photocouv597_2-e1482664611413.jpg\"><img decoding=\"async\" alt=\"big_photocouv597_2\" class=\"aligncenter size-full wp-image-69061\" height=\"300\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/big_photocouv597_2-e1482664611413.jpg\" width=\"600\" \/><\/a>\n<\/p>\n<p class=\"title\">\n\t<a href=\"http:\/\/www.aanda.org\/articles\/aa\/abs\/2017\/01\/aa28964-16\/aa28964-16.html\">Rapporten&nbsp; &quot;Formation of bi-lobed shapes by sub-catastrophic collisions: A late origin of comet 67P&rsquo;s structure&quot; har fokus p&aring;<\/a> vad astronomerna beskriver som en low energy, sub-catastrophic impact. H&aring;ller sig kollisionen inom vissa gr&auml;nser, &ouml;verlever b&auml;gge delarna utan att smulas itu av sm&auml;llen.\n<\/p>\n<p class=\"title\">\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/8308177-origpic-408eda.jpg_0_0_100_100_300_251_100-e1482670378264.jpg\"><img decoding=\"async\" alt=\"8308177-origpic-408eda-jpg_0_0_100_100_300_251_100\" class=\"aligncenter size-full wp-image-69066\" height=\"100\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/8308177-origpic-408eda.jpg_0_0_100_100_300_251_100-e1482670378264.jpg\" width=\"84\" \/><\/a>\n<\/p>\n<h2 class=\"title\">\n\t<strong>Tack f&ouml;r alla julkort<\/strong><br \/>\n<\/h2>\n<p class=\"title\">\n\tTack till alla astronomiv&auml;nner, som mailat eller skickat julkort via snailmail. N&aring;gra stack ut i sk&ouml;rden av h&auml;lsningar.\n<\/p>\n<p class=\"title\">\n\tEtt mycket trevligt hemmastampat julkort kom t ex fr&aring;n<strong> H&aring;kan Barreg&aring;rd:<\/strong>\n<\/p>\n<p class=\"title\">\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/H\u00e4r-far-tomten-fram...-e1482671573578.jpg\"><img decoding=\"async\" alt=\"har-far-tomten-fram\" class=\"aligncenter size-full wp-image-69075\" height=\"313\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/H\u00e4r-far-tomten-fram...-e1482671573578.jpg\" width=\"450\" \/><\/a>\n<\/p>\n<p class=\"title\">\n\tESO passade p&aring; att &ouml;nska god jul s&aring; h&auml;r:\n<\/p>\n<p class=\"title\">\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/potw1551a-e1482671671687.jpg\"><img decoding=\"async\" alt=\"potw1551a\" class=\"aligncenter size-full wp-image-69077\" height=\"253\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/potw1551a-e1482671671687.jpg\" width=\"450\" \/><\/a>Fr&aring;n en kompis p&aring; amerikanska NRAO kom denna h&auml;lsning:\n<\/p>\n<p class=\"title\">\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/04_holiday_card_top.jpg\"><img decoding=\"async\" alt=\"04_holiday_card_top\" class=\"aligncenter size-full wp-image-69080\" height=\"365\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/04_holiday_card_top.jpg\" width=\"300\" srcset=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/04_holiday_card_top.jpg 300w, https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/04_holiday_card_top-246x300.jpg 246w, https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/04_holiday_card_top-164x200.jpg 164w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a>NASA-astronauten <strong>Peggy Whitson <\/strong>twittrade &ouml;ver denna bild till jorden, en selfie p&aring; en viktl&ouml;s tomte ombord p&aring; ISS:\n<\/p>\n<p class=\"title\">\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/peggy-whitson-christmas-socks-e1482672378735.jpg\"><img decoding=\"async\" alt=\"peggy-whitson-christmas-socks\" class=\"aligncenter size-full wp-image-69086\" height=\"450\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/peggy-whitson-christmas-socks-e1482672378735.jpg\" width=\"450\" \/><\/a>\n<\/p>\n<figure class=\"figure article-hero \"><figcaption class=\"fig-cap\" id=\"nointelliTXT\">\n<p style=\"text-align: center;\">\n\t\t<cite class=\"fig-credit\">Bildk&auml;lla: NASA\/Peggy Whitson via Twitter<\/cite>\n\t<\/p>\n<\/figcaption><\/figure>\n<p class=\"title\">\n\tI Lomma driver gamle KvP:aren <strong>Calle Rockb&auml;ck<\/strong> sin egen<a href=\"http:\/\/callerockback.blogspot.se\/\"> underh&aring;llande blogg,<\/a> och i den knyter han d&aring; och d&aring; till vad som skrivs i W-bloggen. God forts&auml;ttning, Calle!\n<\/p>\n<p class=\"title\">\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/15665567_10154714716702976_5980386559296139285_n.jpg\"><img decoding=\"async\" alt=\"15665567_10154714716702976_5980386559296139285_n\" class=\"aligncenter size-full wp-image-69094\" height=\"525\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/15665567_10154714716702976_5980386559296139285_n.jpg\" width=\"350\" srcset=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/15665567_10154714716702976_5980386559296139285_n.jpg 350w, https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/15665567_10154714716702976_5980386559296139285_n-200x300.jpg 200w, https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/15665567_10154714716702976_5980386559296139285_n-133x200.jpg 133w\" sizes=\"(max-width: 350px) 100vw, 350px\" \/><\/a>\n<\/p>\n<p class=\"title\">\n\tV&aring;r fina animation p&aring; ASTB:s egen hemsida inte att f&ouml;rgl&ouml;mma!\n<\/p>\n<p class=\"title\">\n\t<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/logo_jul2.gif\"><img decoding=\"async\" alt=\"logo_jul2\" class=\"aligncenter size-full wp-image-69082\" height=\"256\" src=\"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-content\/uploads\/2016\/12\/logo_jul2.gif\" width=\"253\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Mars &quot;spindlar&quot; utmanar Mars yta erbjuder m&aring;nga &ouml;verraskningar. En &auml;r &quot;spindlarna&quot;, vars sm&aring; ursprung nu observerats n&auml;ra sydpolen. Dessa geologiska fenomen skapas n&auml;r kanske metertjocka koldioxidlager t&ouml;ar upp och bildar sm&aring; f&ouml;rdjupningar p&aring; planetytan (&quot;throughs), som genom m&auml;rkliga geologiska processer v&auml;xer ut och f&ouml;rgrenar sig. I slutstadiet n&aring;r vi fram till den st&ouml;rre spindelformationen. Bildk&auml;lla;&hellip;&nbsp;<a href=\"https:\/\/www.astb.se\/cassiopeiabloggen\/2016\/12\/25\/nr-147-2016\/\" rel=\"bookmark\">L\u00e4s mer &raquo;<span class=\"screen-reader-text\">Nr 147 2016<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"rop_custom_images_group":[],"rop_custom_messages_group":[],"rop_publish_now":"initial","rop_publish_now_accounts":[],"rop_publish_now_history":[],"rop_publish_now_status":"pending","neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts\/69059"}],"collection":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/comments?post=69059"}],"version-history":[{"count":45,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts\/69059\/revisions"}],"predecessor-version":[{"id":69117,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts\/69059\/revisions\/69117"}],"wp:attachment":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/media?parent=69059"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/categories?post=69059"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/tags?post=69059"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}