APOD: December 31, 1995 - The X-ray Sources of M31 <link rel="icon" type="image/ico" href="./favicon.ico"> </head> <body BGCOLOR="#F4F4FF"> <CENTER> <text="#000000" link="#0000FF" vlink="#7F0F9F" alink="#FF0000"> <h1> Astronomy Picture of the Day </h1> <p> <a href="archivepix.html">Discover the cosmos!</a> Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. <p> December 31, 1995 <br> <a href="image/m31_rosat_big.gif"> <IMG SRC="image/m31_rosat.gif"> </a> <br> <b> The X-ray Sources of M31 </b><br> <b> Credit: </b> <a href="http://www.rosat.mpe-garching.mpg.de/">ROSAT</a>, <a href="http://www.mpe-garching.mpg.de/">MPE</a>, <a href="http://www.nasa.gov/">NASA</a> <p> </CENTER> <b> Explanation: </b> Just like our own <a href="ap950908.html">Milky Way Galaxy</a>, the nearest major galaxy <a href="ap950724.html">M31</a> has many star systems spewing high energy <a href="http://www.astro.washington.edu/strobel/lightnotes/lightnotes.html" >radiation</a>. High energy <a href="lib/glossary.html#X-ray">X-radiation</a> is visible to certain satellites in <a href="ap950622.html">Earth</a> orbit such as <a href="http://heasarc.gsfc.nasa.gov/Images/pretty_pictures_rosat.html" >ROSAT</a> - which took the above picture. The X-ray sources in M31 occur in <a href="ap951019.html">globular clusters</a>, the <a href="ap950912.html">spiral arms</a>, and near the galaxy's centre. Probably most of these sources are <a href="ap951226.html">accretion disk binary star systems</a>. M31 has more X-ray sources near its centre than our Galaxy, and the reason for this is currently unknown. <p> <CENTER> <b> Tomorrow's picture: </b><a href="ap960101.html"> Shuttle Engine Blast </a> <p> <hr> <a href="ap951230.html"><</a> <a href="archivepix.html">Archive</a> | <a href="lib/aptree.html">Index</a> | <a href="http://apod.it/uk/">Search</a> | <a href="calendar/allyears.html">Calendar</a> | <a href="lib/glossary.html">Glossary</a> | <a href="lib/edlinks.html">Education</a> | <a href="lib/about_apod.html">About APOD</a> <a href="ap960101.html">></a> <hr> <p> <b> Authors & editors: </b> <a href="http://antwrp.gsfc.nasa.gov/htmltest/rjn.html">Robert Nemiroff</a> (<a href="http://www.phy.mtu.edu/">MTU</a>) & <a href="http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html">Jerry Bonnell</a> (<a href="http://www.usra.edu/">USRA</a>)<br> <b>NASA Technical Rep.: </b> <a href="mailto:jpn@grossc.gsfc.nasa.gov">Jay Norris</a>. <a href="lib/about_apod.html#srapply" >Specific rights apply</a>.<br> <b>A service of:</b> <a href="http://lheawww.gsfc.nasa.gov/docs/lhea/homepg_lhea.html">LHEA</a> at <a href="http://www.nasa.gov/">NASA</a>/ <a href="http://www.gsfc.nasa.gov/GSFC_homepage.html">GSFC</a><br> <b>&:</b> <a href="http://www.mtu.edu/">Michigan Tech. U.</a><br> </CENTER> </body>