The Simonsen T-M Diagram

You've heard of the H-R Diagram. Its a plot of luminosity versus color for stars. Up through the middle runs the main sequence, where typical stars, like our Sun, spend the majority of their lives, steadily converting Hydrogen into Helium.


Veering off to the right and up is the instability strip, where we find stars that have undergone changes in their interiors and are now pulsating, like Miras and Cepheids. You knew I had to slip in something about variable stars, right?

Near the top left is where huge, massive, ultra-luminous stars spend their short lives (for stars anyway), gobbling up their interior resources at a fatal rate. Near the bottom we find the burnt out cinders of evolved stars, the white dwarfs.

Many things can be illustrated using the H-R Diagram, but mostly it is an excellent way to track stellar evolution, the birth, life and death of stars.

I have invented something similar to describe the evolutionary track of amateur astronomers. I call it the T-M Diagram. The vertical axis represents money, in dollars. It is a log scale. The horizontal axis represents time, in months, years and decades; also a log scale.

Through the middle of the diagram we find our normal amateur astronomer as he progresses from an initial minor investment of time and money, say a few books and some binoculars, to more sophisticated and expensive items. After a few months or years the amateur probably purchases a telescope and some accessories, and over a period of years to decades may invest several thousand dollars.


For some, once they have tracked down and observed the Messier objects and some other faint fuzzies, they get the bug to try something else, maybe even contribute to science in some way. After a few years they break from the main sequence and form their own branch of the T-M Diagram. They may become variable star observers, search for novae, supernovea, asteroids or comets, or they may become planetary imagers, employing digital SLRs or CCD cameras.

This invariably leads to larger aperture instruments, computers, CCDs, home observatories and an extreme laundry list of accessories, nay, necessities! Before they know it, usually in a matter of years, they have spent tens of thousands of dollars on their hobby. This is not normal behavior and may lead to serious consequences later.

Even more worrisome is the path taken by the serious astrophotographer. These poor people give up their souls, money and in extreme cases, family ties, to pursue the ultimate images of galaxies and nebulae. The addiction takes hold quickly, and there seems to be almost no limit to the time and money they will invest to get the 1000th perfect image of the Eskimo Nebula.




Across the top of the T-M Diagram we see a dashed line. In spite of its interrupted appearance, this line represents a definite limit. The Mrs. Simonsen Limit, which no amateur in this house will dare to cross.

















Lastly we find, represented by small circular impressions near the bottom of the T-M Diagram, the burnt out remains of once promising amateur astronomers, who after decades pursuing a hobby that has grown into an obsession, or worse, find themselves insane and bankrupt.

We will discuss this troubling trend in astronomy in future blogs, when we address such things as aperture fever and the signs you or your loved one may be suffering from 'astronomy obsession'. Stay tuned.