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Dying Stars Viewed From Death Valley

 

By John Dobson
Published 2004-10-22 13:08:56
From 1973

 

Out through the Furnace Creek Wash we're leaving Death Valley through falling snow. Four years ago we brought the 24 incher ["Delphinium"] into Death Valley, for the first time, through a blizzard in the Tehachapis. We barely got through, leaving 7,000 motorists stranded in the passes. We had the advantage of weight. The telescope weighs nearly 600 pounds. On that first trip it endured five nights of rain and wind. That was its first year and its first long trip. By now it's been through several blizzards and some fifteen nights in the rain. Delphinium was meant for fairer skies but she spends most of her useful life in the mountains and has to take what she gets. By now she has hauled nearly twenty thousand miles and served many thousands of people in the mountains and the deserts, as far south as San Diego, as far east as Arizona.

 

We arrived in Death Valley three nights before Christmas and left on New Year's morning. That gave us nine days and nine nights to entertain the public with our telescopes on the sidewalks and lawns of the Visitor Center at Furnace Creek. Thousands of people came to look. Early in the evenings they saw Venus and Jupiter and sometimes the moon.

 

When the turbulence was low the larger telescopes were often on Saturn or the moon or occasionally on Mars, and on one night on Sirius B, the white dwarf companion of the Dog Star, with a density of thirty tons per pint. It has been pulled together in its own gravitational field till there is no longer any room for the electrons to choose energy states around the atomic nuclei. They must now choose energy states through the star as a whole and further collapse is forbidden by Heisenberg's Uncertainty Principle. Any further decrease in the uncertainly of an electron's position by the further collapse of the star must be made at the expense of increasing the uncertainly of its momentum. This it the terminal ailment of small stars like our sun, making it possible for them finally to cool off without further gravitational collapse.

 

When the darkness and transparency of the sky were good the larger telescopes were often on the Great Nebula in Orion or on the Crab or on NGC 2024 or occasionally on the Horsehead. Early in the evening they were sometimes on the Dumbbell or the Ring or on the globular cluster M-15 [in Pegasus]. Later in the night they were more likely to be on M-81 or 82 or even on M-31.

 

Hundreds of people saw the dark lanes of the spiral arms of M-31 through The Little One [17 incher]. Even in the proximity of the five-day moon it was easy to see. Through the the 24 incher the spiral arms of M-81 were easy. M-81 is nearly four times as far away as M-31, which can easily be seen with the bare eyes from Death Valley. It [M-31] is only two million light years away and is the most distant collection of suns still visible with the bare eyes. The number of suns in M-31 is equal to the number of grains of sixty grit carborundum in twenty tons. It is the largest member of our local group of galaxies.

 

We showed the people M-15 so that they could compare an old, densely populated globular star cluster with the young, sparsely populated clusters in the spiral arms, such as the Double Cluster, or the Pleiades, or the Great Nebula in Orion where the stars are even now forming from the beautiful, bright cloud of gas which contrasts so strikingly with the associated dust clouds. It is in our own wrap of spiral arm and from our own neighborhood it is undoubtedly the brightest, most beautiful and most colorful sight beyond our solar system. Through either of the larger telescopes it is a spectacular sight. Through either telescope it runs far out of the eyepiece field, more so through the 24. We pull the telescopes too far out to the west and let the cloud drift through the eyepiece field while the people watch. On a good night one can see a great deal of detail in the bright, blue-green nebulosity around the six stars in the Trapezium and the bright nebulosity is studded with faint stars. From the time the Great Nebula was reasonably high above the south eastern horizon until most of the visitors had left, one or another of the larger telescopes could usually be pointed to it.

 

This was the most publicized tour we ever took and one of the most successful from the standpoint of the number of viewers and the number of objects viewed, even from the standpoint of the number and size of the telescopes. So many people saw things through so many large telescopes that it elicited a great deal of comment. Many wanted to know where to find us again and several people said that looking through the telescopes had been the highlight of their trip.

 

The Sidewalk Astronomers are Astronomical Entertainers to Her Majesty the People-at-Large. What we need is millions of Sidewalk Astronomers scattered all over the world. If we had several dozen hard-core Astronomical Entertainers in every large city we might be able to get done what we're trying to do. At least half the population of the world should have the opportunity to see the rest of the Universe through large telescopes from beyond the jurisdiction of the city lights and smog. Those who have telescopes should be encouraged to entertain... There is a special beauty in the astronomical knowledge picked up by those who manage telescopes on behalf of the people-at-large. Everyone should see. Everyone should understand. What we do for ourselves is a waste. What we do for others is beauty. Those who help others to see will see. Those who help others to understand, they indeed will understand.

 

Only occasionally are we able to show so many people so many dim objects in skies so satisfactorily dark. The rangers were most cooperative and turned off the flood lights which normally play on the front wall of the Death Valley Museum. Only that cooperation made it possible for us successfully to show the visitors the spiral arms of galaxies, and such dim objects as the Horsehead Nebula, the nearby brighter nebula of dust and gas - NGC 2024, and also the Crab. Once again we saw the stars in the Crab Nebula through the 24 incher. They are difficult to see but worth the effort since one of the two stars near the center is the pulsar responsible for the gaseous envelope around it which we now call the Crab.

 

Only nine hundred and twenty years ago there was no such thing as the Crab Nebula visible in our skies. Only nine hundred and twenty years ago, as seen from our solar system, that star was invisible to us, but by then the center of that star consisted of one huge iron ball from which no further speck of nuclear energy could be extracted to further the delay of its gravitational collapse. It is a rather curious thing that the most powerful explosive in the universe appears to be a large iron ball from which the last speck of nuclear energy has already been extracted. We have chemical explosives like TNT, electrical explosives in the form of these huge balls of iron which, in the long course of stellar evolution, form in the centers of stars more massive than our sun. Over the long course of stellar evolution the energy released by nuclear fusions in these massive stars simply delays their inevitable gravitational collapse till it can delay no longer. When the last speck of nuclear energy has been called up and spent and the center of such a star has thus been reduced to iron it is absolutely powerless against its own gravitational field. It has now become a gravitational explosive. There is no way to prevent its collapse to a neutron star, and when it goes the gravitational energy released to other forms when the iron falls to neutrons lights up the interstellar night with the light of a hundred million suns.

 

From the dust of such exploding stars all our us are born. Most of the materials of which our bodies are made, including the iron, were scattered through the galaxy from the outer regions of these collapsing stars by these brilliant, gravitational explosions during the 5 or 10 billion years before our sun was born.

 

The spinning iron ball whose gravitational collapse powered the explosion which produced the Crab Nebula spins now as a neutron star at the center of the cloud, visible only on a good night and with a fairly large telescope at a distance of some six thousand light years. Thirty times a second it spins and thirty times a second it sends us a flash of light. Thirty times a second it spins but its gravitational field is so strong that it does not fly apart. Its gravitational field is so strong that a spoonful of ice cream splashing on its surface would release enough energy to vaporize a town. It has been pulled together in its own gravitational field that there is no longer any room for the electrons to choose energy states through the star as a whole. Now the electrons sit right on the protons. The certainty in the position of the electron is now bought at the expense of the increased uncertainly in its momentum.

 

The energy of the electron, and with it the uncertainly in its momentum, is pumped up, in that final collapse, by the gravitational field which pulls the star together to almost unbelievable densities and leaves it spinning so hard that for several thousand years the energy of its spin lights up the interstellar night. This is the terminal ailment of stars a little larger than our sun.

 

We are grateful to all those who make this trip possible, and to those who contributed to its success. We are grateful to those who made the telescopes, and to those who hauled them, to those who operated them and to those who contributed to the Transportation Fund. We are also grateful to the rangers whose cooperation made it possible for us to show so many things to so many people, and we are grateful to the gardener for allowing us to set the telescopes on the lawn.

 

Although on this trip we were able to entertain several thousand people with many fine views, billions of eyes are waiting.