by Rex Parker, Phd director@princetonastronomy.org

From Stone to Star. The relationship of stars to common earthly things is closer than one might think. Advances in astrophysics over the past century have revised the story of geology by providing a detailed explanation for how minerals found on earth were created in stars. That process, called stellar nucleosynthesis, was elegantly described to AAAP members at a lecture last fall by Dr Jack Hughes of Rutgers Astronomy Dept. Nuclear fusion in stars is understood to create all the chemical elements up to atomic mass of iron (Fe, atomic number 26). But heavier nuclei cannot be generated at the observed abundances in the universe under the conditions within stars. Rather they are produced through much more energetic and cataclysmic processes, chief among these being supernova explosions. Over time this has seeded the interstellar spaces with vast clouds of particles and gases that are the stuff from which new planetary systems form. Although the 66 natural elements (all found on earth) heavier than Fe make up less than 0.1% of the total mass of the universe, they’re essential to biological life and human society.

Back down on earth, I’ve recently had a close encounter with the great diversity of minerals found in the top layer of our planet. Over the past couple months I’ve moved the family rock and mineral collection to our home in New Jersey. Imagining the processes that created the beautiful and highly variable crystalline rocks and colorful blends of agates and jaspers is a mind-expanding exercise. When touching a nodule of turquoise the realization that the origin lies in stars and supernovae brings home the reality of what astrophysics means to geology, chemistry, and biology. Can’t help but think of Carl Sagan’s words about us being star stuff. When looking through a telescope at emission nebula and “HII regions” where new stars are being born in the deep sky, consider that these precious minerals are being formed right there.

For a good book on the topic, I recommend “From Stone to Star” by Claude Allegre. And keep an eye out for emerging ideas about the formation of the heavier elements. Supernovae are not the only explanation, as their frequency across the universe does not appear to equate with the observed abundances of elements such as gold and platinum. One recent hypothesis is that neutron star collisions can also generate heavier elements. Of course neutron stars are the gravitationally collapsed core products of supernovae, so the latter are not being disrespected by the neutron star hypothesis. The recent breakthrough observation by LIGO in 2017 of gravitational waves, interpreted as being generated by a neutron star merger, has supported this proposal. It has been estimated that the “kilonova” gravitational wave event detected by LIGO (termed GW170917) generated about 10 earth masses equivalent of the element gold!

The AAAP Washington Crossing Observatory is for all club members. As the main hub for observational astronomy, member gatherings, and public outreach, the Observatory is central to the club’s mission. You don’t need to be an expert, just come out on Friday public nights starting April 5 through Nov 1. If you have thought learning more about telescope hardware, software, and technical aspects, I urge you to come out to see what’s up there through the AAAP’s telescopes (see list of equipment below). If you’d like to enter the training program to become qualified to access the observatory 24/7, please contact me or send an e-mail note to observatory@princetonastronomy.org.

Telescope equipment for member use at the AAAP Observatory as of April 2019.

• Paramount-ME #1, robotic equatorial mount
• Mount run with TheSkyX planetarium and control software under Win10 computer.
• Celestron-14 Schmidt-Cassegrain telescope, D=355mm (14-inch), f/11, FL=3900mm.
• New Stellarview 80 mm right-angle finder scope on the C-14.
• Explore Scientific ED127 refractor telescope, D=127mm (5-inch), f/7.5, FL=950 mm, triplet air-spaced apochromatic refractor.
• Numerous 2-inch and 1-1/4-inch eyepieces for these telescopes.
• Starlight Xpress Ultrastar Colour CCD camera.
• Starlight Live and SharpCap software cameras.
• Verizon FiOS is available inside the Observatory.
• Paramount-ME #2, robotic equatorial mount
• Mount run with TheSkyX planetarium and control software under Win10 computer.
• Hastings-Byrne 61/4-inch refractor, f/14.6, FL=2310mm. This fine historic instrument is a great planetary telescope, dating to 1879 with the original air-spaced doublet lens and steel tube intact.
• Takahashi Mewlon-250, D=250mm (10-inch) Dall-Kirkham reflector telescope, with -inch TMB Optical dielectric-diagonal and Feathertouch 2-inch Crayford focuser.
• Numerous 2-inch and 1-1/4-inch eyepieces including Panoptic 27 mm and 41 mm for the M250.
• ZWO ASI 294 Pro color CMOS camera
• Starlight Live and SharpCap software set up for EAA cameras