Winding spiral arms reveal black hole mass


	Winding spiral arms reveal black hole mass

tabsey

6-4-2008 10:52 AM

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tags:

astronomy

tabsey says:

How tightly a galaxy's spiral arms wind up suggests the mass of its central black hole, researchers say.
Francis Reddy

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<div style="margin: 12px 0px; font-family: arial; color: #333333; background: #ffffff; border: solid 4px #e5e5e5; width: 100%; clear: left;"><div class="CM_CTB_Content_Wrap" style="margin: 0px; padding: 0px;background-color: #ffffff;"><div style="border-bottom: solid 1px #dcdcdc; white-space: nowrap; margin-bottom: 8px; background-color: #eeeeee ;background-image: url(http://www.clipmarks.com/images/source-bg.gif); background-repeat: repeat-x; height: 24px; line-height: 24px; vertical-align: middle; padding-bottom: 4px; color: #666666; font-size: 10px;" ><a href="http://clipmarks.com/clip-to-blog/" title="see clips that are hot right now"><img src="http://content.clipmarks.com/blog_embed/14e1ecf3-c632-468b-96cf-619703c39dca/F8763969-5A04-4BA2-BA83-7CB88FDCAC9D/" alt="" width="19" height="19" border="0" style="vertical-align: middle; margin: 0px 4px; display: inline; border: none; float:none;" /></a>clipped from <a title="http://www.astronomy.com/asy/default.aspx?c=a&id=7018" href="http://www.astronomy.com/asy/default.aspx?c=a&id=7018" style="font-size: 11px;">www.astronomy.com</a></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=7018"><div align="center"><img src="http://content7.clipmarks.com/blog_cache/www.astronomy.com/img/B9BF1127-C2B7-482E-8571-D1DA8BC76AC1" alt="M31" /></div></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=7018"><SPAN class="caption">The Andromeda Galaxy has tightly wound spiral arms and a beefy black hole weighing 170 million Suns.  <EM>Conrad Jung</EM> [<A href="javascript:alert('This link contains javascript. Please visit the clip source to follow this link.');" target="_self">View Larger Image</A>]</SPAN></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=7018"><div align="center"><img src="http://content8.clipmarks.com/blog_cache/www.astronomy.com/img/F924E484-101D-4194-9127-3953B11C09D1" alt="M33" /></div></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=7018"><SPAN class="caption">The loose, patchy arms of M33 correlate with its pint-sized 1,500-solar-mass central black hole. <EM>T.A. Rector/M. Hanna (NRAO/AUI/NOAO/AURA/NSF</EM> [<A href="javascript:alert('This link contains javascript. Please visit the clip source to follow this link.');" target="_self">View Larger Image</A>]</SPAN></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=7018"><DIV>Astronomers have long recognized that many spiral galaxies, including our own Milky Way, sport black holes in their centers that weigh millions of Suns. Determining these masses usually requires detailed observations of stellar motions in each galaxy's heart. "That limits you to the nearest 30 or 40 spirals, even with the Hubble Space Telescope," says Marc Seigar at the University of Arkansas, Little Rock.</DIV></blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.astronomy.com/asy/default.aspx?c=a&id=7018"><DIV>Seigar thinks he's found an easier way, one that can be extended to as far as spiral structure can be detected. He led a team that established a relationship between the mass of a galaxy's central black hole and the pitch angle of its spiral arms, a measure of how tightly they wind up. </DIV></blockquote></div><div style="margin: 0px 6px 6px 4px;"><table style="font-size: 11px;border-spacing: 0px;padding: 0px;" cellpadding="0" cellspacing="0" width="100%"><tr><td style="background:transparent;border-width:0px;padding:0px;">&nbsp;</td><td align="right" style="background:transparent;border-width:0px;padding:0px;width:107px" width="107"><a href="http://clipmarks.com/share/F8763969-5A04-4BA2-BA83-7CB88FDCAC9D/blog/" title="blog or email this clip"><img src="http://content9.clipmarks.com/images/c2b-foot.png" border="0" alt="blog it" width="107" height="17" style="border-width:0px;padding:0px;margin:0px;" /></a></td></tr></table></div></div>

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