October 20, 2017

Review: The Stardust Revolution by Jacob Berkowitz.

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Pity the astronomers of yore. Unlike other scientists, they couldn’t take pieces of their objects of study and place them under scrutiny in a lab. Were the heavens truly unchanging and immutable, made of truly different “stuff” than mundane Earthly goods? [Read more...]

16.03.10:Relativity Triumphant over Bizarre Binary.

The unique dance of DI Herculis. (Credit: Simon Albrect/MIT).

The unique dance of DI Herculis. (Credit: Simon Albrect/MIT).

 

   For years, a unique binary system has plagued Einsteinian physics. DI Herculis (DI Her) is a seemingly innocuous binary star about 2,000 light years distant. Type B stars each about five times the mass of our Sun, these stars are in a mutual orbital embrace about 0.2 A.U. apart. Visually, the system is at magnitude +8.5, and the orbit is inclined along our line of sight so that mutual eclipses occur every 10.55 days. First recorded in 1900, this feature allows the systems’ mass, luminosity and orbital characteristics to be known to a high degree of precession. For the past several decades, however, astronomer Ed Guinan at Villanova University couldn’t shake an odd effect; namely, periastron of the two stars is advancing at a rate of only Ľ what’s predicted by Einstein’s theory of general relativity. Is an unseen companion lurking in the DI Her system, or is it Albert himself who was wrong? Prediction of such anomalies as the precession of the perihelion of Mercury is one of the great cornerstones of relativity.  In a massive system such as DI Her, this effect should be even more pronounced. Like the Pioneer anomaly, several would-be theorists have pointed to this discrepancy as a potential chink in the relativistic armor…

 Enter Simon Albrecht of MIT. Using a 1.93-meter telescope to obtain a high-resolution spectrograph of the two suns, a bizarre fact has become apparent; both stars are tipped on their rotational axes, giving them an orbital “kick” at their closest approach. This configuration adequately accounts for the relativistic anomaly. Apparently, DI Her underwent a close passage of another star or massive object sometime in its history. Guinan is relieved, but will no doubt continue to receive a flood of email from alternate-gravity theorists!

Flashback: Remembering the Great Comet of 1910.

The "other" comet in 1910...(Credit: Lowell Observatory).
The “other” comet in 1910…(Credit: Lowell Observatory).
1910 was a heady year both in astronomy and the world at large. The nationalism that would lead to World War I was still fermenting in Europe; the radio was the hot new IPod of the age, and silent movies were yet to be replaced by “talkies” over a decade away. In astronomy, astrophotography was in its infancy, and Edwin Hubble  had yet to make his landmark discovery that would expand our known universe beyond our own Milky Way galaxy… and the public and scientists alike eagerly awaited the close perihelion passage of Halley’s Comet in April. [Read more...]