Gravitational Microlensing - Help!

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star_sirius

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Today I stumble the link below and i'm dying to know more about "gravitational microlensing" device itself! Does anyone out there know or operate a "gravitational microlensing" device? Can I home-make a small scale one myself? Is there any computer software to go with it? Thanks in advance! <img src="/images/icons/wink.gif" /><br /><br />http://www.nzherald.co.nz/index.cfm?c_id=5&ObjectID=10328374<br /><br /><font color="yellow"><br />New way to open Aladdin's Cave <br /><br /> <br />01.06.05 <br /><br /> <br />By Grant Christie <br /><br /> <br />A week ago it was announced that the second definite discovery of a planet orbiting a distant star has been made using a method called "gravitational microlensing". The method uses the gravitational field of one star to amplify the light of a more distant one. It was an astronomical milestone for a number of reasons. <br /><br />While nearly 160 extra-solar planets (exoplanets for short) have now been found, most have been what astronomers call "hot Jupiters". By this they mean massive planets comparable with Jupiter but orbiting very close to the parent star. These are very unfamiliar worlds and quite unlike the planets of our own solar system. <br /><br />The new planet is several times heavier than Jupiter but it lies further from its star than Mars is from the Sun. This means that it will be a cold, gaseous world and more like Jupiter than most of the previous exoplanet discoveries. <br /><br />And that is the real advantage of the gravitational lensing technique. It is more likely to find planets in orbits similar to the Earth, Mars and Jupiter than anything else, so the method is more likely to discover planetary systems similar to our own. In fact, the detection method is so sensitive that in favourable cases it may even be possible to identify Earth-sized planets within the "habitable zone". This is a very important issue in astronomy today</font> <div class="Discussion_UserSignature"> <font size="0" color="#10bdee"><strong>A dazzling bluish luminosity from A distant south pacific.</strong></font><p><br /><img id="cb51e87e-8221-424c-8ff2-78c95122196c" src="http://sitelife.livescience.com/ver1.0/Content/images/store/11/15/cb51e87e-8221-424c-8ff2-78c95122196c.Large.jpg" alt="blog post photo" /></p> </div>
 
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Saiph

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Oh, it's not an actual device they use. The astronomers are looking for, and exploiting, chance alignments of planets and stars. They don't actually "use" gravitational lensing, they observe it, and decipher the cause. It's poor wording , but common in the field. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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star_sirius

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Saiph, thanks for giving me some pointers, I'll look more into it! ;0 <div class="Discussion_UserSignature"> <font size="0" color="#10bdee"><strong>A dazzling bluish luminosity from A distant south pacific.</strong></font><p><br /><img id="cb51e87e-8221-424c-8ff2-78c95122196c" src="http://sitelife.livescience.com/ver1.0/Content/images/store/11/15/cb51e87e-8221-424c-8ff2-78c95122196c.Large.jpg" alt="blog post photo" /></p> </div>
 
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igorsboss

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<font color="yellow">Can I home-make a small scale one myself?</font><br /><br />Sure!<br /><br />Equipment: <br />(1) Telescope<br />(1) Brown dwarf star.<br />(1) Spectrometer attachment for telescope (optional)<br /><br />Procedure:<br />Using the telescope, stare at the empty space around the brown dwarf star.<br />If it gets brighter, you've microlensed something. Study it quickly, because this is the only chance you'll ever get to see this object.<br /><br />The brown dwaf star acts as a really big objective lens (with a central obstruction), because the light is refracted by the brown dwarf star's gravity. <br /><br />Caveat:<br />Since the focal length is measured in light-years, they can be rather difficult to point...
 
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nexium

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That should work with a lot of luck. Finding a brown dwarf star (or unlighted compact star) is difficult as they emit no visable light. An infrared telescope would help find one, and be better sometimes for viewing planets. In worst case, the line up is useful for less than one second per century, as the lensing effect is negligible more than one second of arc from the brown dwarf or typical compact star. Having the telescope mounted in a fast moving vehicle may extend viewing time to several minutes, if you travel the optimum direction which is typically approximately West due to Earth's rotation. Neil
 
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star_sirius

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That's an awesome piece of information. Thank you. Will find a way to aim for a brown dwarf star. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <font size="0" color="#10bdee"><strong>A dazzling bluish luminosity from A distant south pacific.</strong></font><p><br /><img id="cb51e87e-8221-424c-8ff2-78c95122196c" src="http://sitelife.livescience.com/ver1.0/Content/images/store/11/15/cb51e87e-8221-424c-8ff2-78c95122196c.Large.jpg" alt="blog post photo" /></p> </div>
 
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igorsboss

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I take it by the wink you realize how incredibly difficult this really is...
 
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igorsboss

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Since the brown dwarf stars are virtually invisible, the actual technique is quite different from what I described previously.<br /><br />Consider this experiment...<br />Image the same area of sky many times over a period of months. Choose an area of sky densly populated with ordinary stars. Look for changes in the images over time.<br /><br />If you are lucky, a brown dwarf star might pass in front of one of the stars you are looking at. Look for transient arcs of light. These are microlensing events.<br /><br />Count microlensing events over a period of years. Later, use the counts to calculate the number of brown dwarf stars that have passed your field of view. <br /><br />The microlensed star or galaxy isn't particularly important, however. These microlensing events may be used to estimate the number of brown dwarf stars in our galaxy.<br /><br />Why? Brown dwarf stars are a potential form of dark matter. Knowing the number of Massive Compact Halo Objects (MACHOs) in our galaxy can tell us something about cosmology.
 
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star_sirius

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I know. <img src="/images/icons/frown.gif" /> Brown dwarfs are larger than planets but smaller than regular stars, they're stellar failures and consigned to a low-profile life of cooling and contraction. <br /><br />It's irony, a galaxy the size of the milky way probably contains billions of brown dwarfs, they're still very laborious to spot, they emit little light, they can't burn hydrogen and will never become a full-fledged stars since the radial size of a brown dwarf is roughly comparable to about one tenth size of the Sun, the smallest stars are capable to sustain nuclear fusion must have about 8 percent of the mass of the Sun. <div class="Discussion_UserSignature"> <font size="0" color="#10bdee"><strong>A dazzling bluish luminosity from A distant south pacific.</strong></font><p><br /><img id="cb51e87e-8221-424c-8ff2-78c95122196c" src="http://sitelife.livescience.com/ver1.0/Content/images/store/11/15/cb51e87e-8221-424c-8ff2-78c95122196c.Large.jpg" alt="blog post photo" /></p> </div>
 
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star_sirius

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Before, extra-solar planets had been detected by indirectly means :<br /><br />1) perturbations in radio-timing of pulsars<br />2) transit photometry<br />3) doppler spectroscopy<br />4) direct imaging by HST<br /><br /><br />Now, a new second planet has been discovered orbiting a distant star and two Auckland amateur astronomers provided some of the crucial observations by using a powerful new technique called "gravitational microlensing", the only method capable of detecting Earth-sized planets orbiting other stars. The telescopes used by the Auckland astronomers were by far the smallest, but they have proved very useful for the project's success. I thought I could........??. I'm still searching. <img src="/images/icons/frown.gif" /> <div class="Discussion_UserSignature"> <font size="0" color="#10bdee"><strong>A dazzling bluish luminosity from A distant south pacific.</strong></font><p><br /><img id="cb51e87e-8221-424c-8ff2-78c95122196c" src="http://sitelife.livescience.com/ver1.0/Content/images/store/11/15/cb51e87e-8221-424c-8ff2-78c95122196c.Large.jpg" alt="blog post photo" /></p> </div>
 
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