{"id":52,"date":"2018-02-12T23:22:56","date_gmt":"2018-02-12T23:22:56","guid":{"rendered":"http:\/\/blogs.cardiff.ac.uk\/chromoscope\/?p=52"},"modified":"2018-02-12T23:42:51","modified_gmt":"2018-02-12T23:42:51","slug":"neutral-hydrogen-sky","status":"publish","type":"post","link":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/neutral-hydrogen-sky\/","title":{"rendered":"Neutral Hydrogen sky"},"content":{"rendered":"<figure id=\"attachment_53\" aria-describedby=\"caption-attachment-53\" style=\"width: 500px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-53 size-full\" src=\"http:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-content\/uploads\/sites\/532\/2018\/02\/HI4PI_small.png\" alt=\"\" width=\"500\" height=\"250\" srcset=\"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-content\/uploads\/sites\/532\/2018\/02\/HI4PI_small.png 500w, https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-content\/uploads\/sites\/532\/2018\/02\/HI4PI_small-300x150.png 300w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><figcaption id=\"caption-attachment-53\" class=\"wp-caption-text\">A section of the neutral hydrogen sky. Image credit: HI4PI \/ Chromoscope<\/figcaption><\/figure>\n<p>The <a href=\"http:\/\/www.chromoscope.net?w=y\">Neutral Hydrogen sky<\/a> is now available on Chromscope. This all came about because <a href=\"https:\/\/twitter.com\/chris_bloke\/status\/962484124542844928\">Chris Samuel asked<\/a> whether it could included, and pointed towards an <a href=\"https:\/\/www.mpifr-bonn.mpg.de\/pressreleases\/2016\/13\">October 2016 press release<\/a> from the &#8220;<a href=\"http:\/\/www.aanda.org\/10.1051\/0004-6361\/201629178\">HI4PI<\/a>&#8221; team. The data that the team made openly available includes a HEALPix map, which makes it straightforward (well, when you&#8217;ve done it before) to plot to a full-sky Cartesian map, apply a colour, and divide into tiles.<\/p>\n<p>The image shows the\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Hydrogen_line\">Hydrogen line<\/a>\u00a0emission &#8211; radio waves emitted by cold hydrogen gas at a wavelength of 21cm (a frequency of around 1.4 GHz).\u00a0Since the gas is neutral, it must be cold, since if it were heated up to more than a few thousand degrees the gas would be ionised. Ionised hydrogen gas emits light in the visible part of the spectrum, particularly at a specific wavelength called the &#8220;Hydrogen alpha&#8221; (also available in Chromoscope &#8211; giving a nice way to compare the warm and cold parts of our galaxy.<\/p>\n","protected":false},"excerpt":{"rendered":"A section of the neutral hydrogen sky. Image credit: HI4PI \/ Chromoscope The Neutral Hydrogen sky is now available on Chromscope. This all came about because Chris Samuel asked whether [&hellip;]","protected":false},"author":273,"featured_media":53,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[9],"tags":[],"class_list":["post-52","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-data"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8FGUp-Q","meta_box":[],"jetpack_featured_media_url":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-content\/uploads\/sites\/532\/2018\/02\/HI4PI_small.png","_links":{"self":[{"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/posts\/52","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/users\/273"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/comments?post=52"}],"version-history":[{"count":4,"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/posts\/52\/revisions"}],"predecessor-version":[{"id":57,"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/posts\/52\/revisions\/57"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/media\/53"}],"wp:attachment":[{"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/media?parent=52"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/categories?post=52"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.cardiff.ac.uk\/chromoscope\/wp-json\/wp\/v2\/tags?post=52"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}