Berto finds an exoplanet Print E-mail
News - Ons Mense
Thursday, 10 December 2009 17:47
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The Bronberg’s famous backyard stargazer, Berto Monard, discovered the 86th supernova from his Bronberg Observatory on plot 39, Rietfontein.

Berto’s observations recently led to the discovery of an exoplanet, a sub-Saturn-mass planet, which was named MOA-2008-BLG-310Lb. According to calculations it has between 57 en 91 earth masses and is situated roughly on the cusp of its host star’s ‘snow line’ where water freezes.


Berto with his observation equipment
Photo: Sky & Telescope

Berto’s observations were made by the use of a CCD camera to photometrically monitor star brightness. Berto participates in a global network of professional and amateur astronomers known as Micro-lensing Follow-up Network (MicroFUN). This group monitors stars that brighten and fade in a symmetrical pattern characteristic of gravitational microlensing.

According to ‘Sky & Telescope’ this effect, predicted by Einstein’s general theory of relativity, occurs when an intervening star passes directly between the earth and a background star. The intervening star’s gravity deflects some of the background star’s light rays that would otherwise miss the earth. This produces a symmetrical brightening and fading that can last several months.


Berto at his Bronberg Observatory

Sometimes a planet orbiting the foreground star enters the background star’s light path. The planet’s gravidity then adds to the microlensing effect during this brief period, leading to an additional brightening and fading superposed on the longerterm effect from its parent star. When the new exoplanet was discovered, Berto reacted to an alert from the Microlensing Observations in Astrophysics Collaboration. They issued an alert that a 22st-magnitude star in Scorpius was brightening. During the critical few hours, Berto observed the planet entering the light path from his Bronberg Observatory.

 

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