Transcript ASTR 1010 Introductory Astronomy 1: The Solar System

Organic Matter in
the Universe
26 August 2016
Artist’s conception of the view from Prox Cen b
Possible Habitable Planet!
Announced Wednesday
• Around the closest star to Earth, 4.24 ly
• Proxima Centauri b circles a red dwarf
• Discovered indirectly by radial velocity
method
• It is within the habitable zone, where water
could be liquid on its surface
• Planet’s mass about the same as Earth,
but could be very different
• Stay tuned for more later in the course…
New Planet Found!
Proxima Centauri:
Red dwarf, smaller than the Sun
Radial Velocity Method
Planet or Star?
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With the vanishing Alpha Centauri B planet on their minds—as well as other
high-profile planet discoveries that later disappeared—the Pale Red Dot
team very carefully tried to confirm their find. First, the team went back and
reprocessed the observations from earlier this century. When run through a
newer, better pipeline, that tantalizing original signal got stronger.
Next, and very importantly, the team needed to rule out the star itself as a
source of the 11.2-day signal. That’s not easy, considering the cantankerous
nature of Proxima Centauri, which periodically erupts in flares that blast
radiation into space.
“There are a few diagnostic tests which can demonstrate that what you think
is a planet is really due to stellar activity,” says Lauren Weiss of the
University of California, Berkeley. “The authors did all of those, and they
found that the planet hypothesis is holding up for now.”
One of the tests the Pale Red Dot team performed was simply observing
the star, reasoning that any regular, deceptive stellar activity should be
visible from Earth. But observations with multiple telescopes on the ground
didn’t reveal any stellar activity that matched the 11-day period.
Summary
• All known life is based on carbon. Biogenic
elements are abundant
• Life uses carbon’s ability to bond easily to
create a variety of organic compounds
with specific biological functions.
• Large macromolecules: lipids,
carbohydrates, proteins, nucleic acids
• Organics from extraterrestrial
environments rained down on Earth,
adding to those produced here
• Left-handed amino acids show terrestrial
influence