Customer Reviews

Extreme Stars: At the Edge of Creation

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Even though this book is not a "backyard astronomer" type of book, those fortunate enough to have a clear view of the stars at night will enjoy the spectacle even more. Indeed, the author manages to add a three-dimensional sense to the familiar constellation patterns. Let me explain.

The title can be a little bit deceptive: "Extreme Stars" doesn't mean "catastrophic stars", but really "the whole family of stars, from one extreme to the other", which is much more interesting anyway. Especially interesting because James Kaler is a professional astronomer and university teacher; and a gifted writer by the way.

The book is neatly organized. Each chapter deals with one such extreme: faintest, coolest, hottest, brightest, largest, youngest, oldest, strangest. The first chapter is missing from my enumeration, the one that deals with our Sun, which is our reference star for all the other chapters. So, for each category, the author clearly describes the various star types that fit the description, how they were discovered and understood, the physical origin of such an extreme state, what may come after for the star, etc.

But beyond this neat organization, you will discover that stars are really a confusing matter: one star can fit several extremes at the same time, and even get from one extreme to the other during its life... and back. As we travel in (or out of) the main sequence, all types are explained: O, B, A, F, G, K, M, L (and T), DO, AGB, white dwarfs, giants, supergiants, hypergiants, neutron stars, Wolf-Rayet (WN and WC), planetary nebulas, novae, supernovae, black holes, etc. And if you are confused by the plethora of denominations and the apparent lack of unifying scheme in the naming of star types, understand that this is an heritage of a few centuries of equally confused astronomers (still) trying to understand what they were (are) observing.

And throughout the book (when possible), the author links an extreme star with one well know light in our night sky: Betelgeuse, Antares, Alpha Centauri, the Orion Nebula, Deneb, etc. Some of the visually brightest stars are bright because they are close to us, some because they are far but extremely active. Some constellations have many bright stars that are really physically close to each other. Some variables or binaries can be easily observed in action, while some other do move against the background in just a few years.

All those connexions of theories to the real sky gives a tremendous multi-dimensional perspective to the otherwise "flat" sky. Well done.

This is the second book by James Kaler I have read. Prior to this I read his book Cosmic Clouds. A very good book, but this one on extreme stars is much better. If you like astronomy you owe it to yourself to read this book. I have never read such a full and comprehensive analysis of stellar evolution prior to this. Many other books treat star types as if they were like worms or dogs - one never evolves into the other. This book clearly ties together the progress of stars form one form to another. I can not recommend this book highly enough!

Kaler's descriptive aptly summarises the theme of this fine work. Astronomy done well is always a fascinating read, and Kaler's done a masterful job. He takes us into the realm of the biggest, hottest, smallest, coolest, most dense and diffuse stars in our universe. Each chapter is devoted to a type, with examples, history, evolution and likely finales. The text is clear and unambiguous, obviously written for anyone interested in our stellar neighbours. Diagrams and photographs illuminate complex subjects throughout, including some spectacular colour plates in one section. Kaler deserves high praise for a comprehensive and exhaustive presentation untainted by weighty philosophy or arcane mathematics.

Kaler's uses the nearest star, our sun, to launch a comparative view of the more extreme versions of stellar objects. Placed in the middle of the band of stars fitting on the "main sequence", it's a valid starting point. Main sequence stars range from very large and bright to very small and dim. Within that range they follow fairly predictable patterns for a given size and type. Outside that stable range, however, loom some immense exceptions and a plethora of tiny, almost minuscule stellar objects. Orion's shoulder is marked by a star with a diameter nearly reaching the orbit of Jupiter. Another, even greater, reach nearly to Saturn's. Others, as Kaler notes, would "fit inside a small town". Even these minute objects have a life history that tells us much about the universe we inhabit. Kaler is vivid in his descriptions of these objects, but he's even more spirited when dealing with the nuclear processes going on within them. Some stars truly seem to "run amok"!

Stars are distant laboratories where reactions occur impossible to duplicate in Earth-bound facilities. Kaler describes the activities of chemical elements within stellar objects and how their signals tell us about the events occurring there. As stars burn away their hydrogen fuel, various options, some still not understood, may be followed. Electrons jump from shell to shell emitting or absorbing energy. These signals, he notes, are the indicators of luminosity, temperature and even distance. One such signal, of course, is the most significant of all - the "noise" indicating the Big Bang that started it all. One result, however, is clear - without these processes neither our planet nor we would exist. This is because the stars, which began as clouds of hydrogen and dust, become the forges of heavier elements. As Joni Mitchell once sang, "we are all made of star stuff". You don't have to be interested in astronomy to enjoy this book. You need only care about your origins and environment. [stephen a. haines - Ottawa, Canada]

So much of the Universe is unseeable by native human eyesight. Nobody knew of craters on the moon, of Saturn's rings, of the moons orbiting Jupiter, of galaxies or nebulae, of the types of stars..... until the telescope was invented. What fascinates me about this is that it was such a modest telescope that first started revealing these wonders. And once we started to see, we have refined our ways of looking which leads to seeing more, looking harder, seeing more ..... Perhaps if we saw nothing new we would stop looking but that just hasn't happened. In some ways, it seems to me that the rewards for looking are immensely greater than the effort required to see.

Our understanding of stars as being huge thermonuclear explosions constrained in space by the force af gravity is so simplistic. (But even that is a very refined view compared to the understanding prior to a knowledge nuclear physics.) In 'Extreme Stars' we are taken for a journey to the limits of what it actually means to be a ball of gas - not necessarily hydrogen - that is ignited to nuclear burning by the force of gravity. We learn of stars that are big, bright (big does not necessarily mean bright), small, young, old, dirty, decreasing in size as they shed gas via a stellar wind, decreasing in size as they expand and shrink - leaving behind a ring of gas.....

We also learn of the generation of the elements as they are created in the fires of the nuclear ovens that the range of star types create. We learn of stars that collapse to nothingness in a black hole, that blink out in a final extinguishment of their nuclear reactions, that explode leaving tiny remnants that are truly extreme - neutron stars and pulsars.

When I stand outside on a clear night and see the stars gleaming down - distinguished by brightness (which may be due to the star's properties or simply its closeness) and colour only - I marvel at how our understanding of these remote and tantalising objects has developed. This book enormously enhances that sense of the marvellous.

Extreme Stars - On the Edge of Creation (Cambridge University Press) is a remarkably fascinating, in-depth look at stellar evolution from the perspective of the Hertzsprung - Russell (HR) diagram, a chart plotting stellar luminosity against temperature (expressed by spectral classes O B A F G K M). James Kaler illustrates the complexity of stellar evolution by examining extreme stars - the faintest, coolest, hottest, brightest, largest, smallest youngest, oldest, and even strangest stars.

Through the telescope most stars look alike, perhaps with a few showing a slight tinge of color. The key to understanding stars is to measure and analyze their spectra, a subject foreign to most readers. Kaler introduces atomic and molecular spectra early, thereafter steadily advancing the reader's understanding and appreciation of spectral analysis, all in the context of the HR diagram.

The HR diagram shows that most stars brighten with increasing temperature; these main sequence stars lie on the chart within a narrow, curved band stretching from the lower-right corner (dim M stars) to the upper-left corner (bright O stars). Hertzsprung's and Russell's key discovery was that many stars lie outside this main sequence, such as the sub giants, giants, super giants, and hyper giants (and contrastingly, the white dwarfs). Many stellar types move either onto or off the main sequence as they age.

The lower main sequence is the home of many of the faintest (and coolest) stars, grouped as M0 through M10. These faint stars, nearly all invisible to the naked eye, comprise about 50 percent of all stars. Surprisingly, other very faint stars - like the Mira variables that exhibit substantial variation in luminosity over months and years - are found among the giant stars, especially on the Asymptotic Giant Branch (AGB).

The magnificent, beautiful planetary nebulae are among the hottest stars. The brightest stars are actually quite rare, but due to their flamboyance some are well-known to the sky gazer. The largest stars (super giants and hyper giants) are not always the brightest, but are, nevertheless, absolutely awesome. The white dwarfs, among the smallest stars, exhibit a wide range in spectral characteristics; some even have variable luminosities with periods measured in only minutes. Even smaller yet are neutron stars.

The youngest stars, such as the T Tauri variables, as they fire up by burning deuterium, become visible at the "birth line" on the HR diagram, thereafter evolving toward the main sequence. The chapter on oldest stars allows consideration of the evolution of galaxies themselves. A final chapter looks at truly strange stars that reside within the main sequence, their weirdness revealed by their most unusual spectra.

In summary, Kaler's focus on superlatives (brightest, hottest, oldest, etc. ) proves immensely effective. Extreme Stars will appeal both to the amateur astronomer well-acquainted with the night sky and to the scientifically-inclined reader relatively new to astronomy. Five stars to James Kaler for this remarkable book.

Have you ever wondered how many different types of stars are in space or are there planets orbiting them? The book Extreme Stars, At the Edge of Creation, by James Kaler is a must read for the astronomy enthusiast. This book is a fresh approach at examining the lives of stars. It covers all extremes from black holes and neutron stars to supergiants and hypergiants. Kaler takes a unique way of organizing the stars in sections for example the coolest, the hottest and the brightest stars. In each section Kaler includes lots of diagrams and pictures to help the reader relate to examples from the text. He is also very through about each topic and often explains the history behind the star and the links that change stars from one type to another. In one chapter, Kaler explains that giant Jupiter class planets have been found in orbit around certain stars.
Kaler writes in a way that is very thorough and detailed but where even the most novice astronomer can still understand. The graphs and photos also help to clarify some of the more difficult. For example, when he talks about stars and their spectra he will often include a diagram to help show the relationship.
Overall I enjoyed reading this book and I would recommend it to someone interested in astronomy. It is really interesting and shows the great variety of stars that exist in the universe. Especially for people wanting to learn more about stars this book is a must read.

This is the third book by James Kaler I've read--the other two being "Stars and Their Spectra" and "The Hundred Greatest Stars", in that order. The other reviews and the back matter of the book give pretty much all the relevent info on what the book is about: stellar superlatives.

As usual, Kaler's personal enthusiasm for his subject shines through, to a degree exceptional for any scientific text. He knows how to turn a phrase, how to create a provocative image with words that will stimulate the reader's imagination. There is much here to amaze even those who consider themselves well-versed in astronomy.

Much as I hate to say it, though, the book isn't perfect. It feels like it occupies an uncertain valley between the introductory "Greatest Stars" and the more advanced "Stars and their Spectra", like it's attempting to be the best of both worlds. Consequently, there are parts that are wonderfully new...as well as those that are "Hmm, he wrote about this in _____." As was the case with "Stars and their Spectra", I would have liked an appendix for more dyed in the wool geeks like myself. ;)

Though he eschews math and advanced physics, I can't quite recommend it for beginners; in my op, people just getting into his work should read "Greatest Stars", then this, and finally "Stars and their Spectra".

Good hunting!

The stars are so distant that even at high power through a telescope they look like nothing more than colorful points of light. In "Extreme Stars", Kaler shows us that in fact these little luminaries of our night sky come in an astonishing variety of temperatures, sizes, absolute brightnesses, and chemical compositions. A chapter is devoted to each type of extreme star, e.g. the coolest, brightest, youngest, etc.

To me, the most interesting theme of the book is how a single star can actually change from one extreme type to another over its lifetime. For example, the brightest stars (accounting for 'unseen' radiation like ultraviolet and infrared) are the blue supergiants. These inevitably go supernova and often leave behind neutron star cores, which are both the smallest and hottest of stars. Also, the coolest red giants will form planetary nebulae and leave behind white dwarfs, which comprise one of the hottest types of stars at the outset. Another example is the faintest stars, which are so frugal with their fuel consumption that they have the longest lifespans and therefore will be the oldest stars.

The book is written with great enthusiasm and is well illustrated. I do remember one time that Kaler kind of took it into the deep end with his discussion of electron degeneracy and the Pauli Exclusion Principle, but for the most part the book is easily accessible to the interested layman. Amateur astronomers like myself would really dig it.

After reading the book, it made me want to get the telescope out and simply stare at some of these extreme stars for a while. The easiest ones to learn to identify by naked eye are the bright supergiants, like Betelgeuse and Deneb. But there are plenty of others in the other extreme types that are bright enough to see with the naked eye; these can be located with a decent star atlas.

One minor quibble: I feel that Kaler didn't emphasize enough that the vast majority of stars we see are just regular main sequence stars, ranging from perhaps 0.2 to three or four times the mass of the Sun. Extreme stars are relatively rare.

Highly recommended.

This was my first book by James Kahler, and I loved it. The extremes he covers are oldest, youngest, brightest, dimmest, smallest largest, coldest and hottest. In covering all of those he discusses the full lifetimes of stars so that the reader has a good grasp not only of the extreme stars, but of all those in between as well.

And for almost all cases, he shows examples that can be found in the night sky, in common constellations, which greatly enriches my appreciation of what I see when I look up.

No need for a long review here, just buy the book if you are interested in star stuff and don't mind a serious read. This book is very well written and gets deep into the nuts and bolts with out getting mathematical. I especially liked the chapter on neutron stars - my favorite! Very clear explanations of whats going on. Just buy the book.