Milky Way map reveals surprises

<body leftmargin="0" bgcolor="#000060" text="#FFFFFF" link="#FFFF00" vlink="#FF9900"> <table border="0" cellpadding="0" cellspacing="0" width="95%" height="1"> <tr> <center> <td valign="top" width="33%" height="33"> <b> <p class="MsoNormal"><font face="Arial" size="5">Milky Way map reveals surprises</font></p> </b> <p class="MsoNormal"><font face="Arial" size="1">July 13, 2005<br> Special to World Science<br> </font> <font size="2" face="Arial"> <b> <br> </b> </font> <b><font size="2" face="Arial"> Astronomers say they have conducted the most comprehensive structural analysis of our Milky Way galaxy, and found that it seems much different from an ordinary spiral galaxy. <br> <br> The survey using the orbiting infrared telescope provides the fine details of a long central bar feature that distinguishes the Milky Way from more pedestrian spiral galaxies. <br> <br> “This is the best evidence ever for this long central bar in our galaxy,” said Ed Churchwell, a University of Wisconsin-Madison astronomer and senior author of a paper describing the new work in an upcoming edition of <i> Astrophysical Journal Letters</i>, a research journal. <br> <br> Using NASA’s orbiting Spitzer Space Telescope, astronomers surveyed some 30 million stars in the plane of the galaxy in an effort to build a detailed portrait of the inner regions of the Milky Way. </font> </b> </p> <p class="MsoNormal"> <b><font size="2" face="Arial"> The task, Churchwell said, is like trying to describe the boundaries of a forest from a vantage point deep within the woods: “This is hard to do from within the galaxy.” <br> <br> Spitzer’s capabilities, however, helped the astronomers cut through obscuring clouds of interstellar dust by gathering infrared light, a type of light which penetrates these clouds. This provided information on tens of millions of stars at the center of the galaxy. </font> </b> </p> <p class="MsoNormal"> <b><font size="2" face="Arial"> The new survey gives the most detailed picture to date of the inner regions of the Milky Way, according to the astronomers.<br> <br> “We’re observing at wavelengths where the galaxy is more transparent, and we’re bringing tens of millions of objects into the equation,” said Robert Benjamin, lead author of the new study and a physicist at the University of Wisconsin-Whitewater. <br> <br> The possibility that the Milky Way Galaxy has a long stellar bar through its center has long been considered by astronomers, and such phenomena are not unheard of in galactic taxonomy. They are clearly evident in other galaxies, and it is a structural characteristic that adds definition beyond the swirling arms of typical spiral galaxies. <br> <br> The new study provides the best estimates for the size and orientation of the bar, which are far different from previous estimates. <br> <br> It shows a bar, consisting of relatively old and red stars, spanning the center of the galaxy roughly 27,000 light years in length—7,000 light years longer than previously believed. It also shows that the bar is oriented at about a 45-degree angle relative to a line joining the sun and the center of the galaxy. <br> <br> Previously, astronomers debated whether a presumed central feature of the galaxy would be a bar structure or a central ellipse—or both. The new research, the Wisconsin astronomers said, clearly shows a bar-like structure. <br> <br> “To date, this is the best evidence for a long bar in our galaxy,” Benjamin asserts. “It’s hard to argue with this data.” <br> <br> The Spitzer Space Telescope was lofted into orbit in August of 2003. It consists of a telescope and three science instruments.  NASA’s Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope for NASA.<br> <br> * * *</font> </p> </b> <p><b><font face="Arial" size="2" color="#FFFFFF">Send us a <a href="mailto:editor@world-science.net">comment</a> on this story, or <a href="mailto:?Body=http://www.world-science.net/othernews/050820_milkyfrm.htm">send it to a friend</a></font></b> </p> <p>  </center> </p> </td> </tr> </table> </body>