{"id":777484,"date":"2024-02-20T07:59:50","date_gmt":"2024-02-20T12:59:50","guid":{"rendered":"https:\/\/spaceweekly.com\/?p=777484"},"modified":"2024-02-20T07:59:50","modified_gmt":"2024-02-20T12:59:50","slug":"castor-is-6-stars-in-one","status":"publish","type":"post","link":"https:\/\/spaceweekly.com\/?p=777484","title":{"rendered":"Castor is 6 stars in one"},"content":{"rendered":"<p> <br \/>\n<\/p>\n<div>\n<p><iframe loading=\"lazy\" title=\"EarthSky Minute Feb 20: Twin Stars and a Star Cluster\" width=\"1110\" height=\"833\" src=\"https:\/\/www.youtube.com\/embed\/-CT8QtHKQoE?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe><br \/><em>Twin stars and a star cluster.<\/em><\/p>\n<figure id=\"attachment_331534\" aria-describedby=\"caption-attachment-331534\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><figcaption id=\"caption-attachment-331534\" class=\"wp-caption-text\">From a Northern Hemisphere location, face generally <em>northward<\/em> to find the Big Dipper asterism in the constellation Ursa Major. Look mid-evening or later in February, earlier in March. Draw an imaginary line diagonally through the bowl of the Big Dipper, from the star Megrez through the star Merak. You are going in the direction <em>opposite<\/em> of the Big Dipper\u2019s handle. You\u2019ll see 2 stars noticeable for being bright and close together: Castor and Pollux.<\/figcaption><\/figure>\n<h3>Castor, the less-bright Twin<\/h3>\n<p>Castor, in the constellation Gemini the Twins, shines with a bright white light. That\u2019s in contrast to the golden glow of its brother star in Gemini, Pollux. Despite being labeled as twins, Castor and Pollux are not gravitationally bound. Yet Castor <em>is<\/em> gravitationally bound into a multiple system of its own. It\u2019s six stars in one!<\/p>\n<p>Castor\u2019s other designation is Alpha Geminorum. And usually an alpha star is the brightest in its constellation. But Castor is 2nd-brightest in Gemini, after Pollux (or Beta Geminorum).<\/p>\n<p>Castor is about 51 light-years away. Pollux is only 34 light-years away. So Pollux is closer to us. And their distances also show Pollux and Castor aren\u2019t gravitationally bound, but only near each other along our line of sight.  <\/p>\n<p>EarthSky lunar calendars are back in stock! And we\u2019re guaranteed to sell out, so get one while you can. Your support means the world to us and allows us to keep going. Purchase here.<\/p>\n<h3>Castor\u2019s complex star system<\/h3>\n<p>Castor is three pairs of binary stars \u2013 six stars in all \u2013 in a complex dance around a common center of mass. <\/p>\n<p>Even a fairly small telescope will show Castor as two stars. You might glimpse a much-fainter star nearby, too; it\u2019s also part of the Castor system. Each of these three stars \u2013 called Castor A, B and C \u2013 is also double. Telescopes don\u2019t show them as double directly. But a spectroscope \u2013 which splits starlight into its component colors \u2013 reveals each of the three stars as double. <\/p>\n<p>The two larger visible components in the Castor system are hot A-type stars. The smaller components are cool, M-type red dwarf stars. <\/p>\n<p>The mass of all six stars together is, very roughly, about six times that of our sun.<\/p>\n<figure id=\"attachment_465709\" aria-describedby=\"caption-attachment-465709\" style=\"width: 800px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/earthsky.org\/upl\/2024\/02\/Castor-Infographic_depicting_the_sextuple_star_system-wikimedia.jpg\" alt=\"Diagram of a system of 6 stars, with their orbits, and line of stars showing comparative sizes.\" width=\"800\" height=\"747\" class=\"size-full wp-image-465709\" srcset=\"https:\/\/earthsky.org\/upl\/2024\/02\/Castor-Infographic_depicting_the_sextuple_star_system-wikimedia.jpg 800w, https:\/\/earthsky.org\/upl\/2024\/02\/Castor-Infographic_depicting_the_sextuple_star_system-wikimedia-300x280.jpg 300w, https:\/\/earthsky.org\/upl\/2024\/02\/Castor-Infographic_depicting_the_sextuple_star_system-wikimedia-768x717.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\"\/><figcaption id=\"caption-attachment-465709\" class=\"wp-caption-text\">The star Castor is a system of six gravitationally bound stars. There are three pairs of stars, each pair orbiting their common center of mass. The Castor A pair and the Castor B pair mutually orbit their common center of mass. These 4 stars and the Castor C pair orbit their common center of mass. Image via NASA\/ JPL-Caltech\/ Wikimedia Commons (public domain).<\/figcaption><\/figure>\n<h3>Visualizing the separation of the stars<\/h3>\n<figure id=\"attachment_331780\" aria-describedby=\"caption-attachment-331780\" style=\"width: 650px\" class=\"wp-caption aligncenter\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/earthsky.org\/upl\/2020\/02\/Castor-system-hierarchy-of-orbits-e1582412774479.png\" alt=\"Family tree-like diagram showing relationships of six stars.\" width=\"650\" height=\"802\" class=\"size-full wp-image-331780\"\/><figcaption id=\"caption-attachment-331780\" class=\"wp-caption-text\">This figure shows the orbit hierarchy of Castor\u2019s star system, along with each of their orbital periods and separation from each other. Castor Aa and Ba orbit each other, and each have their own stellar companion, Ab and Bb, respectively. Castor C, composed of the binary pair Ca and Cb, is farther away and orbits around Castor Aa\/Ab and Ba\/Bb. Image via Wikipedia.<\/figcaption><\/figure>\n<h3>Another way to find the Twins<\/h3>\n<p>Northern Hemisphere skywatchers can find Castor and Pollux using the Big Dipper as a guide, as shown on the chart at the top of this post. And, from anywhere on the globe, you can use the constellation Orion the Hunter (see chart below) to find the the twins. <\/p>\n<p>Star-hop from Orion to the \u201ctwin\u201d stars Castor and Pollux by drawing an imaginary line from Orion\u2019s bright star Rigel through its bright star Betelgeuse. Extend this line about three times the distance between these two stars.<\/p>\n<p>This line will point to Castor and Pollux. <\/p>\n<p>Want the view from your specific location at a specific time of year? Try Stellarium.<\/p>\n<figure id=\"attachment_331533\" aria-describedby=\"caption-attachment-331533\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio.jpg\" alt=\"Star chart: Orion and Gemini, with a line from Rigel to Betelgeuse in Orion pointing toward Castor and Pollux.\" width=\"800\" height=\"800\" class=\"size-full wp-image-331533\" srcset=\"https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio.jpg 800w, https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio-300x300.jpg 300w, https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio-150x150.jpg 150w, https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio-768x768.jpg 768w, https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio-640x640.jpg 640w, https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio-190x190.jpg 190w, https:\/\/earthsky.org\/upl\/2020\/02\/Orion-pointing-to-Geminio-140x140.jpg 140w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\"\/><figcaption id=\"caption-attachment-331533\" class=\"wp-caption-text\">A line from Rigel to Betelgeuse in the easy-to-see constellation Orion points to Castor and Pollux.<\/figcaption><\/figure>\n<h3> Greek mythology of Castor and Pollux <\/h3>\n<p>The reason for the name Castor is unclear. There appears to be no specific connection with a <em>beaver<\/em>, which is what the word means in Latin.<\/p>\n<p>However, there is much mythology associated with these two stars, typically in conjunction with each other. Generally in mythology they are <em>twins<\/em>. In Greek mythology, Pollux is immortal, the son of Zeus, and Castor is mortal, the son of King Tyndareus of Sparta. <\/p>\n<p>So, they were really half-brothers rather than true twins, with a common mother in Queen Leda. Their conception and birth was a complicated and unlikely affair, though, with their mother succumbing to both Zeus (disguised as a swan) and King Tyndareus on the same night. The resulting birth gave us not only Castor and Pollux but also their sister, Helen of Troy. <\/p>\n<p>According to legend, Castor and Pollux sailed among the Argonauts with Jason in search of the Golden Fleece. By most accounts, Castor was killed in battle and Pollux could not bear to live without him. Zeus allowed Pollux to spend every other day in Olympus with the gods, and the rest of the time in the underworld with his brother. <\/p>\n<p>To honor the brothers\u2019 devotion, Zeus placed their constellation in the sky as a remembrance.<\/p>\n<figure id=\"attachment_359275\" aria-describedby=\"caption-attachment-359275\" style=\"width: 800px\" class=\"wp-caption alignnone\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/earthsky.org\/upl\/2021\/04\/Sidney_Hall_-_Uranias_Mirror_-_Gemini-e1618739172293.jpg\" alt=\"Antique color etching of seated twin boys with lyre, club and bow in a star field.\" width=\"800\" height=\"559\" class=\"size-full wp-image-359275\"\/><figcaption id=\"caption-attachment-359275\" class=\"wp-caption-text\">Castor and Pollux, the Gemini twins, as depicted in Urania\u2019s Mirror, a set of constellation cards from around 1825. Image via Wikipedia (public domain).<\/figcaption><\/figure>\n<h3>Other stories surrounding the stars<\/h3>\n<p>While in many cultures they were the Twins, in India they were the Horsemen, and in Phoenicia they were the two gazelles or two kid-goats. Early Christians sometimes called them David and Jonathan, while the early Arabian stargazers knew them as two peacocks. <\/p>\n<p>Perhaps the most unexpected interpretation for the Twins (along with the rest of Gemini) was as a \u201cpile of bricks\u201d as reported by Richard Hinckley Allen. Apparently the pile of bricks stood for the foundation of Rome, and in that context Castor and Pollux were associated with Romulus and Remus, the city\u2019s legendary twin founders.<\/p>\n<p>The twin stars represent Yin and Yang, the contrasts and complements of life, in Chinese culture. In all of these cases, they represent two of something.<\/p>\n<p>You\u2019ll see why if you find these two stars in the night sky.<\/p>\n<p>Castor\u2019s position is RA: 07h 34m 36s, Dec: +31\u00b0 53\u2032 19\u2033<\/p>\n<p>Bottom line: The star Castor, which appears as one of two bright stars in the constellation Gemini the Twins, is actually a six-star system.<\/p>\n<p><span class=\"cp-load-after-post\"\/><\/div>\n<div>\n<div class=\"post-author\">\n<h4>Editors of EarthSky<\/h4>\n<p>                    View Articles\n                  <\/p><\/div>\n<div class=\"post-tags\">\n<h6 data-udy-fe=\"text_7c58270d\">About the Author:<\/h6>\n<p>The EarthSky team has a blast bringing you daily updates on your cosmos and world.  We love your photos and welcome your news tips.  Earth, Space, Sun, Human, Tonight. Since 1994.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<p><br \/>\n<br \/><a href=\"https:\/\/earthsky.org\/brightest-stars\/best-castor-brightest-second-magnitude-star\/?rand=772280\">Source link <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Twin stars and a star cluster. From a Northern Hemisphere location, face generally northward to find the Big Dipper asterism in the constellation Ursa Major. Look mid-evening or later in&hellip; <\/p>\n","protected":false},"author":1,"featured_media":777485,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[46],"tags":[],"class_list":["post-777484","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-earth-sky"],"_links":{"self":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts\/777484","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=777484"}],"version-history":[{"count":0,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts\/777484\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/media\/777485"}],"wp:attachment":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=777484"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=777484"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=777484"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}