Variable Star Books

Welcome to the AAVSO's list of recommended books on variable stars and other allied subjects. Here you'll find the titles, authors and reviews of books on variable stars and related topics. We hope the reviews will help you make informed decisions on purchasing books appropriate to your interest and level of understanding, whether you're a beginning observer or a seasoned AAVSO veteran.

We've included books specifically devoted to variable stars, as well as books on related topics such as stellar structure and evolution, stellar spectra, history of astronomy and general interest volumes. We even have some science fiction titles of books that have variable stars as part of the plot!

The list of reviews and books we offer will be a continuous work in progress. If you have a book you'd like to see reviewed, or if you have a review of an appropriate book you'd like to submit, please contact aavso@aavso.org.

 

It seems likely to me that Understanding Variable Stars was written with the AAVSO members in mind. It is even dedicated to Janet Mattei! It is certainly the most up-to-date readable description of the various types of variable stars & what is known about each. The book begins with a short history of variable star knowledge, then goes into the usual basic concepts of stellar astronomy. What follows is a systematic review of rotating, eclipsing, pulsating, eruptive, pre-main-sequence & finally, miscellaneous variable stars. My only complaint is that this particular volume does not quite live up to the Cambridge editing standards. There is even one occasion when two figure references in the text refer to the two different figures with the same number, only one of which is present, of course. These problems can be fixed in future editions, however & do not detract much from the flow of the book. Basically, if you observe variable stars, you should read & probably own this book. Thank you, Dr. Percy! —HTN

This is probably the most comprehensive book specifically directed at observing variable stars I have read. It is broken into roughly two sections. The first section describes the myriad types of variable stars and their behavior, including illustrations and light curves. The second half of the book is devoted to the specifics of observing variable stars, preparation and planning, recording and reporting your observations, as well as analysis of the data.

The introductory chapters on the types of variable stars include verbatim descriptions from the General Catalog of Variable Stars (GCVS) along with further explanations and illustrations. This format leads to my only real criticism of the book, which is the fact that often, large portions of the GCVS description are repeated in the accompanying text. I found this an annoying distraction after a dozen or more chapters. The author is to be commended for expanding on the classification scheme used by GCVS to include types and sub-types not officially recognized in the GCVS but commonly used in the literature elsewhere. In fact I learned of some types of variables I had never heard of before reading this book. One of my favorites was the inclusion of MAIA variables, which the author admits may be "like the abominable snowman", in that they "may exist but are extremely difficult to find".

Another unique feature to this book is the inclusion of an 'Observation Key' with each type description. This key indicates the types of stars, their amplitudes, periods and most useful for beginners, the appropriate method for observing them, whether visually, PEP or CCD. The chapters on observing variables cover a wide range of useful topics, from planning and preparation, different methods of observing, variable star data management and analysis and reporting your observations to various variable star organizations. All in all, this book does an admirable job of being an all-inclusive book about observing variable stars and is suitable for all levels of amateur astronomers. —SXN

North's book is a good starting place for an aspiring variable star observer. Beginning with a brief explanation of variable nomenclature, charts & light curves, he then spends almost a quarter of the book on equipment, for both visual & CCD estimates. After that, he delves into each classification of "astrovariable", a term he uses to cover not only variable stars, but AGN's & anything else in the sky that has a light curve. The book comes with a CD-ROM compendium of these light curves. The author is more connected to the BAA than the AAVSO, so the chart examples are not the familiar ones to us, but the good explanations apply on both sides of "the pond". One of the most extensive chapters covers CCD photometry, from the hardware to the data reduction. —HTN

This is by far the most accessible book for beginning variable star observers in print. Everything you need to know to get started in variable star observing is laid out in an easy to follow, logical progression. Levy describes things in a non-technical manner that makes it understandable to everyone. More importantly, his enthusiasm for the subject is infectious and his personal stories and experiences make the book that much more readable. This book could just as easily be described as Variable Star Observing 101. Levy starts off with practical guidance on getting to know the sky, and explains magnitudes, star colors and distances. A short chapter on telescopes and binoculars suitable for variable star observation is followed by a very good description on "how to see" when using them. In part two we are introduced to the family of variable stars, again with a personal touch that includes stories about several specific stars. In this second edition, we are also introduced to CCD cameras and observing techniques, a subject not covered in the first edition. Part three lists suggested variable stars for each season and adds some southern stars not included in the first edition. The descriptions and tips for finding and observing these stars, as well as Levy's enthusiasm, were what got me excited about variable stars in the first edition. I think I ordered or downloaded every chart for every star he recommended when building my original observing program. The miscellaneous stories and chapters at the end of the book seem a bit like an after thought, but the AAVSO and some of its most prominent historical observers are featured so I won't complain too bitterly. If you are just getting started, or contemplating observing variable stars, buy this book first. By the end you will be hooked like the rest of us dedicated observers, and well on your way to enjoying a hobby that will keep you busy and happy for years to come. —SXN

Even though it was published over twenty years ago, this book remains the most comprehensive single text on the subject of cataclysmic variables (CVs). It is written at the level of a graduate text and is not shy about introducing the mathematics and equations that demonstrate the discussions in each chapter. As such, it is probably most appropriate for under-graduate and graduate study, reference for researchers in adjunct disciplines and advanced amateurs.

The book begins with an overview of the historical development of our understanding of CVs and the evolution in our observations of them from the ground to outer space. It then dives right in to the structure of non-magnetic systems, mass transfer and accretion disc theory. The following chapters progress through the various types of CVs, from dwarf novae to nova-likes and novae. About 300 pages in, we are introduced to the world of magnetic systems, Polars, Intermediate Polars and DQ Her stars. The complexity and mathematics is ratcheted up a few notches at this point, so hold on. The final chapters are devoted to the evolution of CVs and population and space density studies. Although the number and typology of CVs we now know has increased tenfold since this book was published, the science and descriptions of the binary systems in this volume remain as relevant today as when it was published in 1995. No self-respecting CV junkie should be without a copy. —SXN

This is an excellent overview of cataclysmic variables (CVs) written at a level that most amateur astronomers interested in CVs can comprehend. It does a fine job explaining the principles underlying the variability of these systems in a style that is highly readable. The mathematics and formulae describing important concepts in the book are mercifully placed in side 'boxes' so the entire text can be read through without being slowed down by equations. This does not make the book any less serious or comprehensive. It is invaluable as a reference for amateurs interested in studying these systems, as well as an undergraduate text. This book progresses through the observations of the stars to the observed characteristics, beginning with the orbital cycle and spectral characteristics. Evolution of the systems is introduced early on, in chapter four, before the subject of types of CVs is undertaken. From chapter five on we are introduced to the specific types of CVs and how they fit into the larger picture, from dwarf novae through magnetic systems. The appendices are also very useful and informative and the bibliography alone is worth the price of this book. This book is a 'must read' for amateur astronomers observing cataclysmic variables. —SXN

This is a technical book & (unfortunately) priced accordingly. Basically, it contains all the theory behind & user's manual for the Wilson-Devinney computer code commonly used to model eclipsing binaries. If you are doing EB modeling, you probably need this book. Most of the mathematics is not too difficult & the worst of it can probably be skipped over if you have a good conceptual understanding of astrophysics, since the computer code does the actual work. Eclipsing Binary Stars, although extremely informative & not lacking in readable style, will not be a one-evening read. Oddly though, there is some levity. In his foreword, Wilson (of Wilson & Devinney fame) lets loose with a string of "punny" variable star names, such as the ultimate eclipsing binary PK Boo. (If you are into this sort of thing, you already know that the Wilson-Devinney code may be downloaded here.) —HTN

Anticipating the deluge of newly discovered variable stars coming from the Hipparcos mission, the authors sought to compile a compendium of characteristic light curves to help in classification. In their preface, they describe their surprise at the widely scattered nature of the published information. In addition to the editors, there are seven different authors contributing on various classes of variables. For that reason, the style & depth of description is not particularly uniform. Also, because the approach is observational, there is not much in the way of astrophysical explanation given (many journal references are given, however). It is very handy, however, to have all this information in one place. Some of the data portrayed, especially for the long-period variables, came directly from the AAVSO. —HTN

This book is translation of a 1982 book in French. It surveys all the different variable classes, with some special attention to some of the author's favorite stars, such as FG Sagittae. The understanding that has accumulated in the last 25 years is missing, of course, as is anything resulting from CCD photometry, space telescopes & the like. However, the explanations are still good & the historical perspective is interesting. The book is out of print, but you might find it under the "new & used" option on amazon.com. —HTN

There are probably more up-to-date popular books on gamma ray bursts (GRB) available. This one came out in 2000 in Dutch, 2002 in English & the field is a rapidly developing one. FLASH!, however might be one of the most entertaining. Schilling is a science writer specializing in astronomy & a contributing editor to Sky & Telescope, so there are no bloopers. I'll be looking for more of his books.

"Armageddon is a Valhalla compared to what happens here. In a fraction of a second the star collapses in on itself. Trillions of tons of hot gas disappear forever through the one-way door of a black hole. Space becomes distorted, time ceases to have meaning, and matter is thrown into a frenzy. The star devours itself from the inside out. In a last agonizing scream the disappearing nucleus of the star spews out two jets of boiling, roiling matter ... They bore burning tunnels through the outer layers of the star, which has no idea of the drama that has come to pass in its dark depths. But the star cannot continue to exist in the face of this cosmic violence. Like a Christmas bauble with a hand grenade inside, it explodes, spitting out an incredible quantity of energy that comes free from its inside."

Thus, perhaps, the prologue draws the video game set deeper into an informative book. The entire book is not written in this "explosive" style, but the style is colorful nonetheless, with a slight, intriguing European accent. Concerning the competition between gravity & nuclear energy production that rules stellar evolution, the author says: "Ultimately, however, it is indeed gravity that wins. Gravity needs no fuel. While a star stokes itself up to prevent a catastrophic collapse, gravity just has to sit by patiently & wait. When the hydrogen supply finally gets used up, the internal pressure drops & gravity makes its move. How fast this occurs depends upon the original mass of the star."

There is also much about the human side of scientific research: international & personal rivalries, getting instrument packages into space by various means, wrangling director's discretionary telescope time, with whom one can share privileged information, even speculation by the girlfriends of graduate students about why gamma ray bursts prefer to happen on weekends & holidays! Tycho Brahe's gold nose, or even Tycho Brahe himself, would not have existed without supernovae like the Stella Nova that he observed in 1572.

It is hard to get anything else done while FLASH! lies around the house, only partially read. —HTN

This is a comprehensive account of RR Lyrae stars, and traces the story from their initial discovery a century ago, through to their present status. This book reviews our current understanding of RR Lyrae stars. It is a unique explanation of the multiple applications of these variable stars for a range of astrophysical problems. Horace A. Smith describes the use of RR Lyrae stars as probes of old stellar populations, both in the Milky Way and other galaxies, and as an outstanding testing ground for stellar evolution and pulsation theories. He stresses the significance of variable stars for our ultimate understanding of the history and scale of the Milky Way and nearer extragalactic systems. For advanced students and researchers of astronomy, this is a definitive account of the modern theories surrounding RR Lyrae stars. —Editors

As far as I can tell, this book is a time machine. Read it & you will travel back to the days when comparison star magnitudes may have come from the Bonner Durchmusterung, no constellation yet had 334 variables in it, a photometer was device that allowed a visual observer to adjust an artificial light source or an image of Polaris to match the program star & delta Cephei was held to be some odd kind of binary system (although Shapley's revolutionary assertion that it pulsates is mentioned). Much attention is paid to the methods of careful observing & record keeping that went into Argelander's BD & other catalogs of the era, meticulous methods that would drive us from the computer age to distraction. Mention is made that Harvard Observatory had recently converted to the practice of writing the comparison star magnitudes directly onto the charts. Reading this book has really caused me to appreciate our roots & also our chart & sequence teams all the more! Interestingly, the book already contains a hint of the era to come: a chapter devoted to "photo-electric photometry"!

Reading this book also pointed me to how far we have come, in slightly less than one century, in the understanding of the stars themselves. In 1915, no nova progenitors had been found in the plate collections. SS Cygni and U Geminorum were totally baffling. Eclipsing binaries, even the beta Lyrae types to some extent, were understood fairly well. But all short-period variables, including Cepheids, were considered to be spectroscopic binaries, since they showed radial velocity changes. Stellar evolution was still conceived as going from "early" to "late" spectral type.

Amateurs of the day were very much encouraged to participate, via the quoted words of Argelander, Pickering, and the editors or Popular Astronomay. In the "Hints for Observers" chapter, there is a brief summary of the founding of the AAVSO (did you know that in 1914, there were 35 members who contributed 14,506 observations of 255 variables?).

In spite of the many changes in the study of variable stars over the last century, some things ... such as CV alert networks ... never change: " ... as Mr. Knott wrote on one occasion to Mr. Baxendell: 'I was greatly amused at receiving your telegram this morning about half an hour after I was starting one to you, and one to Espin, respecting our friend U Geminorum.'" —HTN

A cursory glance at the Encyclopedia almost caused me to dismiss it as "low-level stuff". It is large (enough to hurt if you fall asleep reading it), glossy, and full of color pictures and diagrams. My first impression, however, was wrong. As his web site attests, Kaler is a man joyfully immersed in any amount of trivia involving stars. He explains in the preface to the Encyclopedia, how he wrote his first astronomy book Things That I Know About Stars at the age of eight, including worthwhile information such as "there are two kinds of stars (giants and dwarfs)". He claims the current volume to be an advanced edition of this early book. The Encyclopedia contains mathematics, but "except in the section on stellar structure", not calculus. The myriad explanations of astronomical phenomena make the methods and results discussed absolutely clear. The book shares with Stars and their Spectra Kaler's incredibly detailed HR diagrams, including most stars mentioned by name in the book. [Perhaps the author should publish these in poster form, for the benefit of middle-aged readers.] For the serious amateur astronomer who wants to seriously delve into how we know what we know about stars, but would rather not bother with calculus, The Cambridge Encyclopedia of Stars would be an excellent place to start. In fact, when I finished reading it, I started right over at the beginning, as there is much more information there than can be easily absorbed in one pass. For a reader who would want to employ calculus, The Encyclopedia could still make good background reading, before a dive into a weightier textbook which may not give as clear a descriptive explanation. —HTN

The Cosmic Century is a sweeping overview of our progress in understanding the universe, made during the 20th century. It starts with the "prehistoric" 19th century advances in telescopes, spectroscopy & photography, then moves right into the history of the 20th century advances, separated into those before & after World War II. The end of the book is the beginning of the universe, as described by modern physical cosmology. The style is only moderately technical, although a good understanding of astronomy & physics is assumed. Technical aspects & mathematical discussions are relegated to notes & explanatory supplements. I found this book to be an excellent overview. —HTN

Like most of Kaler's books, Extreme Stars is a compilation of facts about stellar astronomy. The unique thing about this book is the organization. Instead of discussing stars in order of spectral class or mass or age, this book chooses to sort by "extremes": the smallest, the largest, the brightest, the youngest, etc. & lastly "the strangest". Perhaps this organization & the title represent an attempt to grab students' attention from a different angle. Most classes of variable stars & the individual members that are so familiar to us, are discussed somewhere in the book, but the index may be necessary to find them. Unlike with his other books, in this one the author chooses to merge the star index & the subject index, which in my opinion is not an improvement. Extreme Stars is very readable, very clearly written & does contain a lot of factual information. It gives the reader a good perspective on the wide range of phenomena coming under the subject of stellar astronomy. —HTN

In keeping with the title, the through-going theme of this book is supernovae. In support of this theme, the range is wide: stellar evolution, quantum physics, some particle physics, relativity, white dwarfs, neutron stars & pulsars, accretion disks, black holes, gamma ray bursts, dark matter, dark energy, wormholes, string theory, and so on. There is not a single equation, although there is a thorough discussion of multi-dimensional space & some topology. There are also a plethora of clever & helpful illustrations. A great deal of information is packed into a small book, however, all of it explained in Wheeler's extremely lucid fashion. The book is up to date as of the publication date, even on topics that are so far unresolved among specialists. Cosmic Catastrophes originated from & is used in a science class for non-science majors, but definitely not for dummies. In this book, I have found one of the clearest explanations of the accretion disk instability, implicated in dwarf nova outbursts, that I have found anywhere. Five or six thumbs up for this one!

As an aside, Wheeler has also written a very entertaining sci-fi novel called The Krone Experiment, involving the CIA, a mad scientist & an artificial black hole on the loose. —HTN

For readers looking for a technical dive into the interior of a star, this book is a good vehicle. Expect serious mathematics & physics, but also good explanations. The authors follow their exposition of the principles by extensive summaries of some of the numerical results. There is a discussion of pulsating stars, including the "kappa mechanism", which applies to stars in the instability strip. Normal mode oscillations are also discussed. No, I have not actually finished reading the whole book, but I am enjoying the journey. My only complaint is shared with most technical books: the price. Amazon.com usually has some pretty good used-book discounts on technical titles, however. Some of the books are actually not used. It's worth a try. —HTN

This is one of Kaler's best books (the other one being The Cambridge Encyclopedia of Stars). After a brief introduction to quantum physics & the laws governing emission & absorption spectra, plus the history of the spectral classification system, the author addresses each spectral class. Under each, he discusses the famous stars that are in the class, how the luminosity classes are distinguished, as well as many interesting facts about the more unusual stars. One common theme of the book is a very detailed HR diagram, including by name all the stars mentioned in the book. The details are generally too small to see without a magnifier, but each chapter reproduces a vertical slice for just the class under discussion, which is more readable. The book gives all the details of interest to the advanced amateur astronomer, without burdening the reader with excessive mathematics. One of Kaler's fortes is the clear explanation of astrophysics in plain English. If you have an interest in stellar spectroscopy, definitely get this book. You will get your money's worth, because you will read it at least twice. The only problem that I note is that the photos are not very well reproduced, at least in the paperback edition & most spectra are presented in their photographic form. One cannot sometimes easily see the spectral details being discussed. —HTN

(There was also a 1959 Dover Publications edition.) If you are interested in a historical excursion & don't mind a little physics & calculus, Internal Constitution will be well worth your effort, due to Eddington's eloquent & flowing style. Keep in mind that, in 1926, astronomers had only a very vague idea where the energy of the stars came from. Quantum physics was quite new & the opacity parameters were only vaguely known. In fact, even the predominance of hydrogen in the stellar composition was not known. Nevertheless, Eddington was able to deduce quite a lot about stellar interiors that was not too far from the mark. The book includes a chapter on variable stars, where the pulsation of Cepheids is considered. Eclipsing binaries are also covered, including "reflection" effects. —HTN

When I was studying astronomy in the 1970's, there existed a bewilderment of unusual galaxies & unusual radio sources: double-lobed radio galaxies, quasars, Seyferts of various types, QSO's, BL Lac objects. The consensus was that black holes (if they existed) must be responsible for the enormous energy output in some mysterious way, but it was not clear how these various objects were related to each other, if they were. Much has happened in 30 years. GALAXIES IN TURMOIL does an excellent job of tying the field together in a language appropriate for the serious amateur astronomer or astronomy "buff". There is a unifying model, such that each AGN (active galactic nucleus) possesses some or all of certain usual features, depending on the mass & feeding rate of its central, supermassive black hole. A great deal of the variety, which of the features are seen from Earth, it turns out, is explained largely by the viewing angle. For example, if we see the host galaxy more or less flat on, we see most of the features, while some features may be hidden by a torus of obscuring material if the host galaxy is seen edge on. If we happen to be looking directly into one of the high-energy "jets", we see something different entirely. There is a good explanation of "relativistic boosting", which makes the jets appear brighter & more rapidly varying than they would be if they were not traveling toward us at very close to the speed of light.

The last chapter covers some details specifically for the amateur astronomer: how to observe AGN's. A large table is provided, listing 150 or so of the brightest objects, ranging from V=9-ish to V=16-ish. Unfortunately, no information is given about coordinating organizations such as the AAVSO, how to make magnitude estimates, or where to get comparison star information.

Oddly, I find no biographical information in or on the cover of this book. Kitchin writes like a professional astronomer, although not at all obscurely. A quick "google" shows that he is an astronomy educator & a professor at the University of Hertfordshire. He has written a number of books for the amateur crowd, particularly in the Patrick Moore series. By this sample of one, I would say he is good at it. —HTN

"If you ever wondered what the big deal is about spectroscopy or wished you understood it a little better, this books for you. Robinson takes a step-by-step approach to spectroscopy, each chapter building on the ones before it. The book is a worthy addition to any advanced amateur astronomers library." (Michael Bakich, Astronomy, February, 2007)

"In Spectroscopy: The Key to the Stars, Keith Robinson makes spectroscopy approachable for those who are interested in expanding their observational repertoire. Not only is this a good read for any observer thinking of taking up spectroscopy, but it's also suitable for high school or first-year college students in astronomy and physics." (Carolyn Collins Petersen, Sky & Telescope, January, 2008)

Leslie Peltier was simply one of the greatest American amateur astronomers of all time. He discovered six novae, twelve comets and made over 130,000 visual observations of variable stars in his lifetime of observing. This places him firmly at the top of his class in all those categories. The story of what drove him to this kind of dedication and love of the night sky is what 'Starlight Nights' is all about. It is the whole story, from a young boy of five years old glimpsing the Pleiades for the first time, to his rise as one of the great observers of all time. His writing style is so personable and modest you can't help but admire the quiet strength and passion of the man. If you ever wondered what drives people to leave the comfort of their warm beds to observe variable stars through bitter cold nights, or if you have forgotten where your passion for astronomy came from, read this book and you will know. Simply put, this is the best book about stargazing ever written. I consider it one of the prize possessions of my personal library. —SXN

This small book is the story of Miss Henrietta Leavitt, whose work with the Cepheids in the Magellanic Clouds led to the discovery of the period-luminosity relation, a major "rung" in the "cosmic distance ladder" that enables measurement of the size of our own Milky Way galaxy & the distances to others. Henrietta Leavitt was one of several "computers" working for Dr. Pickering at the Harvard College Observatory in the early part of the century. Some of the others were Annie J. Cannon & Antonia Maury, both instrumental in developing the spectral classes as we know them. Pickering is said to have hired women because they were satisfied with smaller wages, but in the process he does seem to have opened fascinating opportunities for a few of them. The author's astronomical explanations are basic to the point of boring just about anyone in the AAVSO, but the insights into astronomical history & life as a computer are fascinating. —HTN

Many of Heinlein's early books (such as The Red Planet and Rocket Ship Galileo) featuring young people coming of age in the environment of space. Variable Star is in that style. Heinlein died in 1988, leaving only detailed notes for this unwritten book; by popular demand from fans, Spider Robinson was recruited to develop the notes into the book. Without giving too much away, I can set up the beginning scenario. A young man, at his senior prom, discovers that his fiancee is not quite as she has been representing herself. Although she expects her boyfriend to be overjoyed by the revelation, he is actually so disgusted that he goes on the mother of all drinking binges and signs onto a starship, bound to colonize a distant world around a star named Peekaboo. Life aboard the "relativistic tin can", its propulsion & methods of communication are imaginative, entertaining. Although there is a variable star, after a fashion, directly involved in the plot, there is nothing of the science of variable stars in this book. It is very well written, however & definitely holds the reader's attention. —HTN

A cast of rather bizarre characters set off in a starship to capture a plasma creature known as a star dragon, which has been detected living in the accretion disk at SS Cygni. [Don't they need timely Quick Look data from the AAVSO before approaching this system?] As outrageous as the setting may be, the book is actually quite readable, fun & even informative. The author is an astronomer & the book's preface references the June 2000 VSOTM. The dynamics of the mass transfer, accretion disk & the outbursts are all well described. Enjoy! —HTN

I really do hate to be reviewing books that are out of print, but this one is really worth it. It is science fiction, in the best sense: it is full of science, even an HR diagram, which may be a first for a novel. It is also a classic of the apocalyptic disaster novel genre, although it's a bit dated, as a lot of the plot revolves around Y2K issues. The facts that must be stretched to make this story, involve the mass of Sirius B & some mass transfer from Sirius A, etc. The rest is a classic plot: a nearby supernova (which serendipitously goes off around Y2K), anticipated by a graduate student & a post-doc, who seldom sleep & are ridiculed by everyone else, but who turn out to be right. There is also a rich Japanese amateur with a robotic telescope. Lastly, there is a major pre-Y2K apocalyptic cult involved in the story, which is very well described. At least one of the authors is clearly an astronomer; Eric Kotani turns out to be a pen name. The book not only describes the process of modeling astrophysical phenomena, but it also gives a good insight into how peer-reviewed science works in practice. It's definitely a good read. Very entertaining. —HTN

Science fiction these days can be divided into "soft" and "hard" varieties, along the line of the boundary between fantasy & true science fiction. Fantasy normally involves at least one dragon & often some swords. Hard science fiction involves interstellar travel, nanotechnology, cybernetics, artificial intelligence, alien races, etc. Enhanced mental capability (ESP) and totally made-up physics necessary for interstellar travel do not generally detract from hard science fiction, if these enhancements are described in a way that allows the reader to suspend disbelief. From a Changeling Star is so hard that it has an iron core, although only very briefly. The star (fully) involved is one of the AAVSO favorites. I would rate this book about one third good plot & characters, one third nanotechnology & enhancement to the laws of physics, one third just plain astrophysics. The protagonist is an astrophysicist. It's a fun read. —HTN