Podcaster: Dr. Al Grauer


Title: Travelers in the Night Eps. 249 & 250: Cool Star Homes & Shooting Star’s Daddy

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s two stroy:

  • Dr. Michaël Gillon and his team examined nearby red dwarf stars for exoplanets. They found 3 planets circling a 39 light-year away star now called Trappist 1.
  • The Geminid meteor shower in December is left over from 3200 Phaethon, an asteroid discovered in 1983. This asteroid may in its own turn be an ejected chunk of asteroid 2 Pallas, the second asteroid that was found, having been discovered in 1802. Phaethon appears to eject the meteorites each time it makes close passes to the Sun in its 523.5 day orbit.

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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249E – Cool Star Homes

Recently Dr. Michael Gillon of the University of Liege in Belgium and a team of astronomers hypothesized since that approximately 2/3 of the stars in our neighborhood are red dwarf stars some of them might host inhabitable planets. To test this idea the researchers began to carefully monitor some nearby red dwarfs with a robotic telescope in Chile to see if any of them the have regular dips in brightness which indicate the presence of planets orbiting them.

This team of astronomers were delighted when a faint star in an infrared star catalogue showed regular dips in brightness indicating the presence of three planets. Followup observations by the European Southern Observatories’ 8 meter telescope in Chile confirmed the presence of three Earth sized planets orbiting a star now known as TRAPPIST-1. This extremely faint red star is only slightly larger than the planet Jupiter and puts out 0.05% of the energy of our Sun. Two of its Earth sized planets orbit every 1.5 and 2.4 days receiving four and two times the radiation the Earth receives from our Sun. They are probably two hot to be habitable. The third Earth sized planet orbits farther away and thus might have life permitting temperatures on its surface.

The discovery of three Earth sized planets orbiting the extremely, cool, faint red dwarf star TRAPPIST-1 suggests the possibility of the presence of many more relatively nearby Earth like planets. The next generation of ground and space based telescopes will tell us about their surface conditions.

250E – Shooting Star’s Daddy

Every year before Christmas the Geminid meteor shower treats us to a fast, bright, and reliable light show which occurs when the Earth passes through a stream of dust and small rocks orbiting the Sun. Now we are able to pinpoint the source of these shooting stars which to us appear to come from the constellation of Gemini.

Every 523 days the 3 mile in diameter Earth approaching asteroid Phaethon is closest to the Sun. At this point in its orbit it receives nearly eight times the dose of solar radiation that heats the surface of the planet Mercury to 800 degrees Fahrenheit. To find out what such an encounter does to Phaethon, NASA astronomers observed it with the twin STEREO spacecraft when it was only 15 solar diameters from the Sun’s surface. To their surprise Phaethon suddenly got twice as bright indicating that it likely to have burped out a cloud of dust and gravel which in turn reflected more sunlight in our direction.

The path of the meteoroids which create Geminid shooting stars confirm that were ejected from the asteroid Phaethon when it made close approaches to the Sun. Without this source of replenishment this material would have long ago been depleted by the Earth’s gravity. Take time to enjoy these gifts of the asteroid Phaethon by going to place far from city lights in mid-December.

In 2017 this strange little asteroid Phaethon will approach to within about 27 times the Moon’s distance from us and will be the subject of intense study by humans.

For Travelers in the Night this is Dr. Al Grauer.

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