Frontiers of Astronomy Community Lectures
Are we made of stardust? This is the question Manuel Peimbert answered
during his Frontiers of Astronomy Community Lecture about the origin
of the elements delivered on April 18 at the IfA Manoa auditorium. As
you might have guessed, the answer is "yes."
Peimbert explained that hydrogen, the lightest element, as well as some
of the helium in the Universe, formed during the first four minutes after
the Big Bang, the giant explosion that created the Universe. Hydrogen and
helium make up about 98 percent of all matter. Stars the size of our Sun
convert hydrogen to helium, and then eventually, helium to carbon. When
these stars die, they leave a cloud of dust and gas (known by the misnomer "planetary
nebula") that expands at the rate of 10 kilometers per second (over
22,000 mph) around a small white dwarf star.
Larger stars, those with at least eight times the mass of the Sun, make
heavier elements, including oxygen, neon, magnesium, silicon, and iron,
as well as helium and carbon. When these giant stars die in a supernova
explosion that creates even heavier elements, they leave a very dense neutron star and a cloud
of gas and dust that expands at speeds of at least 2,000 kilometers per
second (over 4 million mph).
June's Frontiers lecturer, Bill Bottke,
investigates the nature of comets and asteroids.
The gas and dust sent into the interstellar medium by dying stars gets
recycled into a new generation of stars. That is why newer generations
of stars have more heavy elements. It is around the stars with greater
amounts of heavier elements that planets are most likely to form. Everything
in this room, including you, Peimbert explained, is made up of elements
that formed from stardust.
Bill Bottke of the Southwest Research Institute, Boulder, Colorado, will
give the next Frontiers of Astronomy Community Lecture on Tuesday, June
27 at 7:30 p.m. in the IfA Manoa Auditorium. The topic will be "CSI
Solar System: Using Computer Models to Investigate the Nature of Comets