Wednesday, April 3, 2013

OBAFGKM (RNS)


One of my all-time favorite classes was my Introductory to Astronomy class (taken in two parts over two semesters), way, way back during my first stint in college in the mid-to-late-80s. I couldn’t believe I was actually getting credit to learn this stuff, stuff I’d been a huge fan of, a voracious reader of, a devoted disciple of, since as earliest as I can remember. Be it reading science fiction as a pre-teen, thumbing through our Colliers and Funk and Wagnall’s Encyclopedias, or carrying around my beloved physics book like an additional appendage, I loved reading about it all. Stars, planets, satellites, asteroids and meteorites, nebulae and galaxies, black holes, electromagnetic radiation, the chemistry of stars, relativity, space travel – you named it, I eagerly consumed it.

Now, a year or two out of high school, I was officially studying it.

Needless to say, I aced both classes with ease. Which is not to say they were extremely difficult classes and I was a genius. No, I just was so familiar with so much of it, having seen it all countless times before.

One thing the classes did do for me was flush out my knowledge. I remember spending a rainy afternoon in the darkened auditorium going deeply into the zones and belts of Jupiter. Heavenly! A few weeks later the mechanics of stellar evolution – the life and death of stars – was finally explained to me by a human voice.

There was a chart I’d seen before (in my beloved physics book, for example), a diagram called the Hertzsprung-Russell Chart. It’s a graph of stars plotted along two axes, luminosity and temperature. Most stars fall on the chart in such a way that it forms a diagonal swish. This is known as the “Main Sequence.” Some stars are clustered in groups above and below it. The diagram is used to explain the life cycle of stars.

Curiously, stars are labeled, going rightward from the axis intersection, as Type O, B, A, F, G, K, M, R, N, S. Type O stars are brilliantly whitish-blue and superhot. Temperatures cool and colors dim as you progress to the right; M stars are relatively warm and dull red. Don’t remember what R N S stand for, except they are often found in parentheses. The sun, a mid-sized star of moderate temperature, yellow in coloration, is a G star. Each letter is further subdivided into tenths; the sun is, specifically, a G2 star.

Though we were all thinking it, it was the professor himself who revealed to us the mnemonic for remembering this strange sequence of letters for stellar classification.

Now, a word about my professor. He must’ve been around forty, ancient in my still-teen-aged eyes. Dressed in the shabby chic of the intelligentsia: a cross between Indiana Jones and a sidewalk hobo. He had a big, shaggy beard and a slight slouch due to a pot belly. A bemused tone to his voice as if he were perpetually recalling an inside joke relating to whatever topic he was speaking about. He was a decent enough guy, though in a class of a hundred or so I obviously did not get to know him. But I had a good idea what he was doing twenty years prior.

Anyway, according to my astronomy professor, the most common mnemonic to remember stellar class is:

Oh, Be A Fine Girl Kiss Me.

Then he adds:

Right Now Sweetie.

Then, that bemused chuckle. Did you know there’s another way to remember this weird bunch of letters? Yes, it’s one he and his friends and classmates came up with way back when.

It goes:

Old Beer And Fat Guys Kill Me.

Then he adds:

Richard Nixon Says.

An inadvertent chuckle racks his body like slapped jello. Nervous laughter permeates the hall. Me, I guess I laugh because everyone else seems to want to … or, more likely, thinks they should. Not quite sure I get the joke, or whatever the source of the amusement is. This is at the start of my collegiate liberal indoctrination, so I’m viscerally aware of all the leftist antagonism towards Nixon at this point.

Bottom line, it was a weird moment in a long and strange college career, one I’ve never forgotten all these years. I don’t begrudge the professor his little slip, because honestly I have no idea what it’s supposed to me. And it’s doubtless a fraction of a fraction of what today’s high schoolers must face in the Big (and probably Unnecesary) Leagues. But that in itself is a source of another post.

Me, I still use the first mnemonic.


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