A very bright gravitational microlensing event

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There is a paper out today on a very bright gravitational microlensing event (by far the brightest observed to date) that occurred last october.<br /><br />http://arxiv.org/abs/astro-ph/0703125<br /><br />To summarize, gravitational microlensing can occur when one object passes almost exactly in front of another object along our line of sight. The foreground object's gravity bends the light from the background object, and if they are very well aligned then it can magnify the background object so that it becomes substantially brighter than it would otherwise be (as much as a factor of 40x brighter, as in the case described in this paper). <br /><br />When Einstein first noted the possibility of microlensing, he quickly dismissed it as impossible to ever observe on the grounds that the chances of two stars being aligned so perfectly are infinitesimal. Indeed, for bright stars (V < 12) the chance at any given moment that it will be microlensed would be about 1 part in 100 million, and since there are only a few millions such stars altogether, the chances of seeing any of them microlensed at a given moment is on the order of a percent. There is an interesting line from the paper on this: "Such a calculation<br />may have influenced Einstein to resist the determined eforts by Hungarian engineer R. W. Mandl to get Einstein to publish his microlensing formulae and perhaps also to compose a letter to the editor of Science to 'thank you for your cooperation with the little publication, which Mister Mandl squeezed out of me. It is of little value,<br />but it makes the poor guy happy.' (Renn et al. 1997)"<br /><br />If you look at fainter stars that are farther away the chances are higher since the farther stars have many more potential objects that can be in front of them, and the greater distance between the source and the lens and the lens and us means that alignment does not have to be as perfect to get a lensin <div class="Discussion_UserSignature"> </div>

 

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I forgot to mention. One of the cool things about this result is that a lot of the observations of this star (including some of the initial discovery observations) come from the Center for Backyard Astrophysics, which is a group of observers around the world, including many "amateurs", who conduct continuous monitoring of bright cataclysmic variable stars with small, backyard telescopes. Part of the beauty of looking for and studying bright variable stars is that anybody can do it - if you've got a telescope and want to contribute to astronomy and also want to see some really cool natural phenomena, I highly recommend looking at variable stars. And a great way to learn more about it is via organizations such as the American Association of Variable Star Observers ( http://www.aavso.org/ ). <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

Thanx for catching this.<br />It will be really exciting if the microlensing object can indeed be spotted within a few years to contrain it's position and mass.<br />A piece of hard data!! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[robnissen]

VERY interesting article. Thx for the post. <img src="/images/icons/smile.gif" />