book reviews

Astronomy and Astrophysics Books

Extreme Ultraviolet Astronomy
by M. A. Barstow and J. B. Holberg
Cambridge, 2003


E xtreme ultraviolet (EUV) covers the range between 10 to 100 nanometers. In space, EUV is mainly produced by optically thin plasma in the outer atmospheres (coronas and chromospheres) of metal-rich stars, where temperatures can reach 105 to 106K. This region of the spectrum is also packed with recombinant emission lines from helium, iron, and other elements. But its most defining characteristic is the famous Lyman-alpha forest, which is a dense maze of different versions of the neutral hydrogen (H I) Lyman alpha absorption line caused by redshifting of ultraviolet radiation as it passes through different clouds of interstellar gas. The lines of H I absorption start at 121.6 nm and get closer together as wavelength decreases, culminating in a strong continuum absorption cross-section at the Lyman limit of 91.2 nm, beyond which EUV is greatly attenuated for distant objects. This means that in the EUV, only a few bright nearby stars are detectable. Detector signals for these are in the range of 0.001–0.01 photon/sec/Å.

As if that weren't bad enough, EUV astronomers must also deal with hydrogen emission in the geocorona, the difficulty in focusing short-wavelength UV, and the inability of EUV to penetrate the atmosphere. Thus, good data are hard to come by, and EUV astrophysics is still mainly in the source cataloging stage. You might think that astronomers would play to the advantages of EUV and study the interstellar medium instead of the stars. But no, stars are still the stars of astrophysics, and the ISM gets only one short chapter.

This book describes the nuts and bolts of various satellite missions up to the Extreme Ultraviolet Explorer, which was switched off in 2001, and discusses the data that have been obtained, and the problems interpreting the results. There are many graphs, diagrams, spectra, and tables of EUV sources. Solar EUV spectroscopy is not discussed.

An Introduction to Radio Astronomy, 2nd ed
by B. F. Burke and F. Graham-Smith
Cambridge, 2002


T his book describes how radio signals are received and processed in single-aperture radiotelescopes (i.e., dishes) and then moves on to aperture synthesis and interferometry. The authors give the most important equations, deriving some and pulling the rest out of a hat.

Starting with Chapter 8 we start getting some actual astronomy, with nice discussions of polarization, radio sources, and pulsars, and introductions to radio signals from the interstellar medium and, of course, the cosmic microwave background. In some places the science has moved on since this book was written; for example, they write that most of the carbon is in linear chains instead of, as we now know, nanodiamonds and polycyclic aromatic hydrocarbons. But most of the stuff here is still true, and it's a good introduction.

The figures are mostly contour plots, with many graphs and a few low-quality pictures. Watch out: CUP re-released this one in 2008, but it's still only the 2nd edition. A third edition was published in 2014.

Radio Astronomy, 2nd ed
by John D. Kraus
Cygnus-Quasar, 2004


R adio astronomy started with Jansky's 1932 discovery of “star static.” Although it progressed slowly at first (it was some years before they were even able to detect the sun), radio astronomy eventually provided the essential clue, in the form of the microwave background, of the origin of the universe. Radioastronomy is also the best way we have of studying chemistry in space. This awkwardly shaped book, a reprint of the 1986 edition, is spiral-bound, or more properly helix-bound, perhaps in honor of Kraus's invention of the helical antenna. The publication quality is more typical of a 60s era book, with poor quality figures and blurry text. The field has changed dramatically in the 25 years since this book was published. In particular, hot topics like interferometry, which provides the highest resolution of any astronomical observing method, are scarcely mentioned. Modern receiver components like HEMTs are not mentioned at all. But Kraus was an outstanding educator, and Radio Astronomy is still highly regarded for its clear explanation of the mathematical background that is still essential for radioastronomy.

In contrast, An Introduction to Radio Astronomy by Burke and Graham-Smith (reviewed above) is more up to date, but far less rigorous, and has much less detail on antennas (which was Kraus's specialty) and other hardware. An excellent treatise on interferometry is Interferometry and Synthesis in Radio Astronomy by Thompson, Moran, and Swenson.

Observational Astrophysics
by Robert C. Smith
Cambridge University Press, 1995, 443 pages


T his undergraduate-level introduction to astrophysics, suitable for students with little or no background in astronomy, contains a few equations and mediocre-quality grayscale illustrations. Most practicing physicists would know this material already.

Modern Astrometry, 2nd ed.
by Jean Kovalevsky
Springer, 2002


A t the beginning of this book, the author tries to convince us that astrometry is a boring subject, full of dry, tedious calculations. This is backed up by some strategic Freudian slips, such as calling something "a monotonous function of the wavelength λ" [p.133]. Whether he's sincere, or just trying to keep out the competition, Kovalevsky fortunately fails. Astrometry, revitalized by the ESA's Hipparcos star mapping project, is as fundamental and important for astrophysicists as reaction kinetics is for chemists. Anyway, you can't escape this author: there are only two textbooks in this field currently in print, and Kovalevsky has written them both, the other one being the much more expensive Fundamentals of Astrometry.

However, in addition to lots of caffeine, readers will need a solid technical background to get through this book. Astrometry uses 3-dimensional trigonometry, of course, but also calculus and relativity. The math is put to good use: optical aberrations, reference systems, techniques for determining star positions, observing and measuring equipment, chronometry, and interferometry are all covered. Spectrometry and photometry are not discussed.

Astrophysical Techniques, 5th ed.
by C. R. Kitchin
CRC Press, 2009


T his is an undergraduate-level book that focuses on imaging technology. No color photos, only graphs and equations. Describes detectors for visible light and X-rays. There are chapters on detectors, imaging, photometry, spectroscopy, and astrometry. There is only a brief section on radioastronomy.

Astronomical Spectroscopy, 2nd ed
An Introduction to the Atomic and Molecular Physics of Astronomical Spectra

Moved to here

Solar System Astrophysics:
Background Science and the Inner Solar System, 2nd ed
by E. F. Milone and W.J.F. Wilson
Springer, 2014, Astronomy and Astrophysics Library


T his book is badly mistitled. It's actually a college-level introduction to geological astronomy. There's very little physics here—just a few grainy color pictures of Mars, and some diagrams and descriptions of what the rocks (perovskite, ilmenite, pyroxene, etc.) are like on different planets. But it would be unfair to say this book is Brian Cox with math.

The authors start with rudimentary celestial mechanics, then move on to the Sun and the rocky planets. The math is very, very gentle—nothing more than basic calculus and an occasional Legendre polynomial—which should make it easy for students to follow.

And lots of rocks. If you're already an astrophysicist, you already know there are lots of rocks up there, and you won't get much out of this book. I bought this book hoping to learn something about the Sun before I observed the solar eclipse, but there was only a short chapter on the Sun.

It turns out that much of what we were taught about the planets in school was wrong. One side of Mercury does not continuously face the Sun. The Moon isn't a solid ball of rock—it has a molten core, unlike Earth, but like Venus and Mars, and thus has no magnetic field. Both the Moon and Mercury have water ice. Venus rotates clockwise on its axis, unlike the other inner planets, so the Sun rises in the west. (Or, equivalently, you could say that Venus is upside-down.)

The authors casually mention that after the Earth and Moon become tidally locked, as will happen in a few billion years, the Moon will start to lose angular momentum. Instead of flying away, as astronomers used to think, someday it will smash into the Earth.

What the average person cares about, of course, is the rocks that might come smashing through their living room this week and make them miss the latest episode of Here Comes Honey Boo Boo. With this book in hand, they can calculate that a 1-kg asteroid smashing into the Earth will release the equivalent of 630 kg of TNT. If the asteroid were to break up, the small pieces would be ablated by the atmosphere, lessening the overall impact. Somebody should take this book and pound all science fiction movie screenwriters over the head with it—literally, if necessary—until they get that message.

The companion volume is Solar System Astrophysics: Planetary Atmospheres and the Outer Solar System (reviewed here).

oct 26, 2014

Fundamental Astronomy
Karttunen, Kröger, Oja, Poutanen and Donner, eds.
Springer, 5th ed, 2007


A lthough the authors' names may sound like the names of Santa's reindeer, this is a serious college-level textbook on astronomy written by professional Finnish astronomers. It contains lots of equations and some astrophysics, many grayscale illustrations, and 34 color plates. Each chapter has solved example problems and exercises which are accompanied by answers in the back. An understanding of calculus and linear algebra is recommended. The book contains a few factual errors, like saying the Green Bank radiotelescope is in Virginia instead of W.Va., but the authors' command of English is generally excellent, even to the point of attempting an occasional witticism.

Fundamental Astronomy derives the principal equations of celestial mechanics and provides a quantitative understanding of orbits, tides, and the sources, effects, scattering, and spectra of solar and stellar radiation. The authors also take great pains to keep the subject interesting by including interesting facts. For example, they say the Earth and moon will someday rotate synchronously: some parts of the globe will never see the moon again, and others will see it fixed in the sky, just as the Earth is fixed in the moon's sky. Saturn's heat and high winds, according to the authors, are produced by potential energy released as helium atoms sink into the planet's core. Some giant stars are twelve thousand times less dense than Earth's atmosphere, while others are a billion times more dense. Some cosmic rays are so energetic that a single particle could lift a copy of the fourth edition of Fundamental Astronomy by one centimeter. This is stuff you gotta know to live.

Extragalactic Astronomy and Cosmology: An Introduction
Peter Schneider
Springer, 2006


A nother outstanding undergraduate-level astronomy textbook is Schneider's Extragalactic Astronomy and Cosmology. This one is distinguished by beautiful color images and even color graphs throughout the text, as well as exceptionally clear writing. Schneider's professional interest is gravitational lensing, and this topic is covered better than in most other textbooks. Students will love this book. Even professional scientists, though they may find it rather light reading, will appreciate the effort and thought that went into it. The only problem is an occasional PCism sneaking into the text. For this we can blame the translator.

Handbook of Infrared Astronomy
Cambridge Observing Handbooks for Research Astronomers 1
by I. S. Glass
Cambridge University Press, 1999


I nfrared radiation brings a powerful new perspective to astronomy. It allows us to see through dust, observe dimmer and colder objects, and identify organic molecules in space. This little 185-page paperback gives a satisfactory introduction to the physics of infrared emission, and good descriptions of infrared optics, the transmission of infrared radiation through the atmosphere, and the absorption and scattering by dust and gas in space, with lots of equations, spectra, and graphs, all of which are clear and easy to follow. Although too short to be a real "handbook," this book is a great source of references to more complete material including, most significantly, NASA's IRAS data and other surveys that were done before this book was written in 1998. Perhaps the most interesting section is on the instrumentation, which uses cryogenically cooled detectors and exotic techniques. But this section is also the most out of date. The order of presentation is also problematic. For example, tables of J,H,K,L and N band intensities are presented well before these terms are defined. Even so, it's a good introduction to what is probably the hottest topic in astronomy.

A new trend in publishing seems to be to make paperback versions of ten- or twenty-year-old textbooks and try to sell them as "new" books. This is especially true in books on infrared technology. Readers who doesn't notice the old publication date find themselves reading about slide rules and obsolete technology. This book appears to be an exception, but Hey!--be careful out there.

See also Electromagnetic radiation books
See also Interstellar astrophysics books
See also Plasma physics & astrophysics books