March 24, 2019

27.04.11: Detecting “Exo-Aurorae.”

Planetary Scientists may soon have a new technique in their arsenal in the hunt for exo-solar planets. Current tried-and-true methods involve measuring tiny radial velocity shifts, catching a gravitational lensing event, or watching and measuring a tiny dip in brightness as a planet transits its host star.

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Astro-Event: An Asteroid Occults a Bright Star.

One of the best occultations of a bright star occurs this week for observers along a line from western Canada down the U.S. west coast. At around 10:00 UT, on the morning of April 6th, 14th magnitude asteroid 824 Anastasia will occult, or pass in front of, the bright +2.5 magnitude star Zeta Ophiuchi for up to 8.6 seconds. This is a rare event in that the occulted star will be visible with the naked eye! Stellar occultations give us the rare opportunity to profile the shape of an asteroid; if enough folks are lined up along the graze line and make and submit accurate observations, a chord map of the “shadow” of the asteroid can be plotted. Binary asteroids have even been discovered by amateur astronomers using this method! Anyway, if you’re located anywhere along the predicted path and the sky is clear, don’t miss this rare event!

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23.9.9 CoRoT-7b: A Rare Earth.

The “Super-Earths” are getting smaller. Recently, the ESA announced that an exoplanet discovered on February 3rd of this year by the CoRoT (Convection Rotation and planetary Transit) satellite is one of the lightest yet… at about five Earth masses, this transiting exoplanet is about twice the diameter of the Earth. But don’t pack your bags just yet; CoRoT-7b as its designated, also zips around its host star every 20.4 hours at a distance 23 times closer than Mercury! This bakes the rocky world with temps in excess of 2000 degrees Celsius. The parent star itself is slighter cooler and younger than our Sun. Follow up measurements by HARPS, the ground based High Accuracy Radial velocity planet Searcher spectrograph at the La Silla Observatory in Chile helped tease out the radial speed and yielded an unexpected bonus; another Earth-like world, CoRoT-7c, which orbits at a relatively sedate 3 days and 17 hours and is 8 times the mass of the Earth. Such bizzare systems may become the norm in the coming years, as exoplanet detection technology becomes more sensitive. The CoRoT-7 system is located about 500 light years away in the plane of the Milky Way galaxy in the constellation Monoceros.