科学家发现最冷恒星 表面温度像地球夏天
<p><span word="The">The</span> <span word="temperature">temperature</span> <span word="of">of</span> <span word="the">the</span> <span word="surface">surface</span> <span word="is">is</span> <span word="like">like</span> <span word="a">a</span> <span word="hot">hot</span> <span word="summer">summer</span>'<span word="s">s</span> <span word="day">day</span> <span word="in">in</span> <span word="Arizona">Arizona</span> <span word="or">or</span> <span word="Seville">Seville</span> - <span word="and">and</span> <span word="would">would</span> <span word="be">be</span> <span word="quite">quite</span> <span word="pleasant">pleasant</span> <span word="for">for</span> <span word="humans">humans</span>. <span word="It">It</span>'<span word="s">s</span> <span word="the">the</span> <span word="coldest">coldest</span> <span word="object">object</span> <span word="ever">ever</span> <span word="photographed">photographed</span> <span word="outside">outside</span> <span word="our">our</span> <span word="solar">solar</span> <span word="system">system</span>.</p><p><span word="But">But</span> <span word="WD">WD</span> 0806-661 <span word="B">B</span> <span word="is">is</span> <span word="not">not</span> <span word="a">a</span> <span word="planet">planet</span> - <span word="it">it</span>'<span word="s">s</span> <span word="a">a</span> <span word="very">very</span> <span word="small">small</span> <span word="star">star</span>. <span word="Its">Its</span> <span word="mass">mass</span> <span word="is">is</span> <span word="just">just</span> <span word="six">six</span> <span word="to">to</span> <span word="nine">nine</span> <span word="times">times</span> <span word="the">the</span> <span word="gas">gas</span> <span word="giant">giant</span> <span word="Jupiter">Jupiter</span>.</p><p><span word="Penn">Penn</span> <span word="State">State</span> <span word="Associate">Associate</span> <span word="Professor">Professor</span> <span word="of">of</span> <span word="Astronomy">Astronomy</span> <span word="and">and</span> <span word="Astrophysics">Astrophysics</span> <span word="Kevin">Kevin</span> <span word="Luhman">Luhman</span>, <span word="who">who</span> <span word="discovered">discovered</span> <span word="the">the</span> <span word="object">object</span> <span word="said">said</span>, "<span word="It">It</span> <span word="is">is</span> <span word="a">a</span> <span word="very">very</span> <span word="small">small</span> <span word="star">star</span> <span word="with">with</span> <span word="an">an</span> <span word="atmospheric">atmospheric</span> <span word="temperature">temperature</span> <span word="about">about</span> <span word="as">as</span> <span word="cool">cool</span> <span word="as">as</span> <span word="the">the</span> <span word="Earth">Earth</span>'<span word="s">s</span>."</p><p><span word="The">The</span> <span word="astronomers">astronomers</span> <span word="used">used</span> <span word="Nasa">Nasa</span>'<span word="s">s</span> <span word="Spitzer">Spitzer</span> <span word="space">space</span> <span word="telescope">telescope</span> - <span word="the">the</span> <span word="most">most</span> <span word="sensitive">sensitive</span> <span word="space">space</span> <span word="telescope">telescope</span> <span word="on">on</span> <span word="Earth">Earth</span> - <span word="to">to</span> <span word="find">find</span> <span word="the">the</span> <span word="cold">cold</span> <span word="star">star</span>, <span word="scanning">scanning</span> 600 <span word="near">near</span>-<span word="earth">earth</span> <span word="stars">stars</span> <span word="for">for</span> <span word="objects">objects</span> <span word="orbiting">orbiting</span> <span word="them">them</span>. <span word="Infrared">Infrared</span> <span word="telescopes">telescopes</span> <span word="are">are</span> <span word="used">used</span> <span word="because">because</span> <span word="cold">cold</span> <span word="objects">objects</span> "<span word="shine">shine</span> <span word="out">out</span>" <span word="brightly">brightly</span> <span word="in">in</span> <span word="the">the</span> <span word="images">images</span>. <span word="The">The</span> <span word="record">record</span>-<span word="breaking">breaking</span> <span word="star">star</span> <span word="is">is</span> 63 <span word="million">million</span> <span word="light">light</span> <span word="years">years</span> <span word="from">from</span> <span word="Earth">Earth</span> <span word="and">and</span> <span word="orbits">orbits</span> <span word="a">a</span> <span word="dense">dense</span>, <span word="collapsed">collapsed</span> "<span word="white">white</span> <span word="dwarf">dwarf</span>" <span word="star">star</span>.</p><p><span word="The">The</span> <span word="star">star</span> <span word="is">is</span> <span word="a">a</span> <span word="brown">brown</span> <span word="dwarf">dwarf</span> - <span word="and">and</span> <span word="formed">formed</span>, <span word="like">like</span> <span word="other">other</span> <span word="stars">stars</span>, <span word="out">out</span> <span word="of">of</span> <span word="a">a</span> <span word="cloud">cloud</span> <span word="of">of</span> <span word="dust">dust</span> <span word="and">and</span> <span word="gas">gas</span>.</p><p><span word="But">But</span> <span word="because">because</span> <span word="it">it</span> <span word="failed">failed</span> <span word="to">to</span> <span word="accumulate">accumulate</span> <span word="enough">enough</span> <span word="mass">mass</span> <span word="from">from</span> <span word="the">the</span> <span word="dust">dust</span> <span word="cloud">cloud</span>, <span word="the">the</span> <span word="thermonuclear">thermonuclear</span> <span word="reaction">reaction</span> <span word="that">that</span> "<span word="lights">lights</span> <span word="up">up</span>" <span word="normal">normal</span> <span word="stars">stars</span> <span word="fail">fail</span> <span word="to">to</span> <span word="ignite">ignite</span>.</p><p><span word="The">The</span> <span word="new">new</span> <span word="brown">brown</span> <span word="dwarf">dwarf</span>'<span word="s">s</span> <span word="surface">surface</span> <span word="is">is</span> <span word="between">between</span> 27 <span word="and">and</span> 80 <span word="degrees">degrees</span> <span word="centigrade">centigrade</span> - <span word="so">so</span> <span word="in">in</span> <span word="places">places</span>, <span word="it">it</span>'<span word="s">s</span> <span word="a">a</span> <span word="temperature">temperature</span> <span word="humans">humans</span> <span word="might">might</span> <span word="enjoy">enjoy</span>.</p><p><span word="Ever">Ever</span> <span word="since">since</span> <span word="brown">brown</span> <span word="dwarfs">dwarfs</span> <span word="first">first</span> <span word="were">were</span> <span word="discovered">discovered</span> <span word="in">in</span> 1995, <span word="astronomers">astronomers</span> <span word="have">have</span> <span word="been">been</span> <span word="trying">trying</span> <span word="to">to</span> <span word="find">find</span> <span word="new">new</span> <span word="record">record</span> <span word="holders">holders</span> <span word="for">for</span> <span word="the">the</span> <span word="coldest">coldest</span> <span word="brown">brown</span> <span word="dwarfs">dwarfs</span> - <span word="the">the</span> <span word="objects">objects</span> <span word="are">are</span> <span word="seen">seen</span> <span word="as">as</span> <span word="valuable">valuable</span> <span word="laboratories">laboratories</span> <span word="to">to</span> <span word="help">help</span> <span word="us">us</span> <span word="understand">understand</span> <span word="the">the</span> <span word="atmospheres">atmospheres</span> <span word="of">of</span> <span word="extrasolar">extrasolar</span> <span word="planets">planets</span> <span word="with">with</span> <span word="Earth">Earth</span>-<span word="like">like</span> <span word="temperatures">temperatures</span>.</p>
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