Organization: Travelers in The Night
Description: Today’s 2 topics:
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Bio: Dr. Al Grauer is currently an observing member of the Catalina Sky Survey Team at the University of Arizona. This group has discovered nearly half of the Earth approaching objects known to exist. He received a PhD in Physics in 1971 and has been an observational Astronomer for 43 years. He retired as a University Professor after 39 years of interacting with students. He has conducted research projects using telescopes in Arizona, Chile, Australia, Hawaii, Louisiana, and Georgia with funding from NSF and NASA.
He is noted as Co-discoverer of comet P/2010 TO20 Linear-Grauer, Discoverer of comet C/2009 U5 Grauer and has asteroid 18871 Grauer named for him.
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365 – Tabby’s Star
The mystery of Tabby’s star began to unfold when in 2015 Dr. Tabetha S. Boyajian [boy-AA-jee-uhn] of Louisiana State University and her team published a paper describing the irregular dips in the light output of what otherwise would seem to be a garden variety star over the period 2009 to 2013. Subsequently a list of proposed explanations include swarms of comets, large asteroids, a debris disk, and even a massive alien megastructure.
In what appears to be the best scientific explanation of the strange behavior of Tabby’s star, Dr. Brian Metzger of Columbia University and his team propose that the dips in brightness of Tabby’s star are the result of its having swallowed one or several of its planets in the recent past. Their calculations published in the Monthly Notices of the Royal Astronomical Society suggest that this cannibalism occurred between 10 and 10,000 years ago depending on the mass of the devoured objects. In their model the gravitational energy released as an object or objects spiral into the outer layers of Tabby’s star caused it to brighten while we were not looking and what we are seeing is it now returning to normal with perhaps dips also caused by debris passing across our line of sight. The authors are going to monitor any further activity by Tabby’s star to see what else there is to learn.
All is not lost for those with the alien megastructure point of view since this idea cannot be completely ruled out by the data.
366 – 3 Explorers
Recently, my Grandsons, Dane and Hank joined our asteroid hunting team at the Catalina Sky Survey 60 inch telescope on Mt. Lemmon.
The most interesting of our discoveries, 2017 KJ32 is only 16 feet in diameter, orbits the Sun once every 315 days, and can come closer to us than the communications satellites. 4 days and 16 hours before Dane, Hank, and I spotted it, 2017 KJ32 passed about 41,000 miles from the surface of Earth traveling at a relatively slow speed for an Earth approaching asteroid of 1.6 mi/sec. By the time 2017 KJ32 came into one of our images it was already 768,000 miles from Earth and was traveling away from us at 1.5 miles per second. A few weeks later it was too faint to be detected by our most powerful telescopes.
It is interesting to speculate that given 2017 KJ32’s speed and orbit that perhaps it is a piece of our Moon which was blasted loose when a larger asteroid or comet impacted the lunar surface. Humans have found more than 240 meteorites on the Earth’s surface whose chemical composition suggests that they came from our Moon. These moon rocks were launched from the Moon’s surface by an impacting object and traveled around the Sun for a while before being captured by the Earth’s gravity. When such an object enters the Earth’s atmosphere, it explodes, and sometimes rains a few pieces onto the ground for us to find as lunar meteorites.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by Astronomical Society of the Pacific. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!