Sirius: the Brightest
Diamond in the Night Sky
Reviews
Sky & Telescope December 2007
PAUL
DEANS
Dog-Star
Science
Many
Bad Jokes and puns came to mind as I prepared to peruse Sirius: Brightest
Diamond in the Night Sky. The author, Jay Holberg, has probably
heard them all, given that he has spend much of the past 20 years studying the
Dog Star and its nearby Pup. Fortunately,
Holberg has turned all that experience in a tale that's a pleasure to read.
The
book opens with an in-depth discussion of Egyptian, Greek and Roman mythology
surrounding Sirius. Part 2 ("The
Nature of Stars" starts with this comment: "The long intellectual journey from
viewing Sirius and other stars as the heavenly counter part of myth and
superstition, to the realization that the stars are actual material objects
governed by physical laws, spanned nearly 25 centuries."
"AhA!"
I thought. That's how the author
turned musing on one object - Sirius - into a 265-page book: by expanding the
topic's boundaries. For instance,
this second part includes the discovery of planetary motion, the misconception
of "fixed" stars, stellar parallax, and Newton's laws of gravitation.
Holberg,
isn't contend to merely summarize how astronomers determined that the pup
(Sirius B) is a white dwarf. Instead,
Part 3, "The Physics of Stars", opens with an account of the first visual
observation of the Pup in 1862 and then traces a century of work by
astronomers, physicists, chemists and mathematicians that eventually leads to
an understanding of stars in general, and white dwarfs in particular. All the while the story of Sirius, and
the prominent part it played in these discoveries, is woven throughout the
narrative.
From
ancient mythology through centuries of science the book explores long-standing
controversies (including the alleged connection between Sirius and the Dogon
tribe) and closes with modern research.
In between is a well-written tale that’s ostensibly about the brightest
star in the nighttime sky but which is actually a marvelous dissertation that
reveals how science advances.
_______________________________________________________
Contributing
editor Paul Deans took
this review seriously and kept the jokes to himself.
_______________________________________________________
Journal for the History of Astronomy - August 2007 (Vol.
38 p386)
SIRIUS
The
story of Sirius epitomizes much of astronomical history. As such, Sirius is the only star (well,
other than our Sun) that can support a whole book. The first book in Sirius (by Holberg) is a history book, not
an astrophysical treatise. Many
fun stories are told, the writing is engaging, and the historical analyses are
insightful, I especially appreciate the in-depth and original research.
Holberg
tells this story of Sirius as a connected whole. We have the astrometry reported in the Almagest, followed by
its use by Halley to deduce the proper motion of the star. Then, small variations on this motion
led to the discovery by Bessel that Sirius was orbited by a dark star. This companion was discovered in 1862
by the Clarks trying out a new lens, with rapid confirmation by Bond and
Struve. Adams, Russell, and
Eddington were all involved in the realization that Sirius B is not a normal
star, but what we now call a white dwarf that has very low luminosity and very
high density. Fowler and
Chandrasekhar took this result and explained it with the new quantum and
relativistic physics, despite Eddington's famously disputing the mass limit for
white dwarfs. This situation was
turned around with Adam's spectroscopic measures of Sirius B that confirmed
Einstein's prediction of gravitational redshift from General Relativity. The situation was turned
around again with spacecraft observations that use the modern physics to derive
incredibly accurate properties for the Pup Star, for example with the Hubble
Space Telescope's returning an orbit that gives a mass of 1.00 ± 0.01 solar mass.
This
basic story from Ptolemy to HST is further extended both to ancient times and
into the future. Holberg starts
the book with how the early Egyptians worshipped Sirius and used it as the
basis for their calendar. He also
covers the legendary Sirius in Greco-Roman society as well as briefly in other
cultures around the world. Holberg
also extends the history of Sirius into the future, where he describes the
certain and inevitable history of the system until its ultimate demise as a
wide binary star composed of two 'cold' white dwarfs. So the book covers from 2276 B.C. until A.D.
10,000,0002,000.
Sirius
has spawned several 'mysteries', including why Ptolemy called it 'red', why the
Dogon tribe in Africa is reported to know about Sirius B, whether there is a
third star in the Sirius system, and why a New Age cult committed mass
'suicide' to travel to Sirius. I am
impressed with the way Holberg handles these topics. For example, the treatment of the Dogon traditions is
different from all other treatment that I have seen in that he looks closely at
the primary data. Thus, Holberg
has extensive interviews with two anthropologists who where there at the time
and place that the lore was collected, he airs a debate on the original lore
collector hidden from us in the anthropological literature, he quashes the idea
that Benjamin Bannekar had Dogon heritage, tells of his own relevant experience
in remotest Africa, and refutes various astrophysics points claimed to be in
the Dogon tradition.
Jay
Holberg is a classical stellar astrophysicist based at the University of
Arizona. He specializes in white
dwarfs as viewed from ground-based and space-based telescopes (including HST,
EUVE, Voyager, IUE, and FUSE).
Sirius is a focal point of his astrophysics. His intimate knowledge is apparent in the last two chapters,
devoted to the history of modern space observations of Sirius and to the future
history of the star system. For
three decades, I have been following the unfolding story of Sirius, and I see
his account as a good history (with perspective balance and details).
The
book has no foot notes, but instead has an extensive list of 280 references
separated by chapter in the back.
I count 150 of these are primary source material, often from private
letters, musty archives, or unpublished papers.
This
book is for historians, with the broad insights supported by original source
material. The book is also for
teachers who might base an entire astronomy history class around the theme of
Sirius from ancient to modern times.
And this book is also for the amateur and professional astronomers who
appreciate the good stories skillfully woven together. I think that this book
is itself a new gem in our night sky.
Louisiana
State University Bradley
E. Schaefer
BBC Sky at Night - July 2007 (#26 p102)
SIRIUS 
< A full account of the brightest star in the sky
To
write a complete book about a single star might sound like a daunting task, but
Jay Holberg, a senior research scientist at the lunar and planetary laboratory
in Arizona, has done so with success.
The
Brightest Diamond in the Night Sky,
Sirius is certainly an exceptional star, at least from our point of view. At a mere 8.6 lightyears from us it is
also one of closest neighbors.
Among the 20 most brilliant stars in our sky, only Alpha Centauri is
closer. Every nation has legends
about it and in historic times it was important to the Egyptians because its
times of rising with Sun could be used to predict the annual flooding of the
Nile, which was vital to the whole economy of their civilization.
There
are several mysteries associated with Sirius. For example, why did some ancient stargazers call it
red? Much more recently it has
been linked with strange and pseudo-religious cults, one of which ended in
tragedy. And there is of course
the Companion, the nearest white dwarf star and certainly the most famous. Less than a century ago, the nature of
this star was a complete puzzle even to the world's leading astronomers.
Jay
Holberg deals with all of these topics, not forgetting to give an excellent
description of the history and future of the Sirius sytem. The book is meticulously researched and
isn't marred by a few tiny and unimportant historical slips. It's a fascinating read and will appeal
equally to the newcomer to astronomy and the serious student. This is recommended without the
slightest hesitation.
***** Patrick Moore
Southern Stars - June 2007 (Vol.46, no 2, p25)
Review by William Tobin
Jay
Holberg has chosen Sirius as the subject of this charming and well-written book
which covers both the lore and the physics of the brightest star in the sky.
Though
a southern object, at declination - 17° Sirius is well-known in both
hemispheres. Holberg begins with
its importance to the Egyptians five millennia ago under the name Sophet. Its heliacal rising (the first
visibility in the dawn sky as Sirius escapes westwards from its annual 70-day
invisibility in the glare of the Sun) occurred just prior to the flooding of
the Nile, so it is not surprising that the Egyptians linked the star with Isis,
the goddess of fertility and the fecundity of nature. The early Greeks were one of many cultures that associated
Sirius with dogs and wolves, and for them its heliacal rising announced the
sweltering heat or 'dog days' of late summer. The heliacal rising occurs in cooler weather south of
the equator, where we find that the Maori word 'takurua' is synonymous with
both Sirius and winter.
Holberg
next reviews the rise of heliocentrism and the idea, to quote a charming
drawing that he reproduces from the 16th century, that space outside
the solar system is "foelicitye garnished with perpetuall shinnge glorious
lights innumerable". Attempts to
set up a reference frame for measuring the celestial coordinates of these
'shininge lightes' foundered on Procyon and especially Sirius, which did not have
uniform proper motions. In 1844
the German astronomer Bessel suggested gravitational perturbations by unseen
massive companions as the cause, noting perceptively that "light is no real
property of mass. The existence of
numberless visible stars can prove nothing against the existence of numberless
invisible ones". This was the
"foundation of an Astronomy of the Invisible". (Johan Mädler, 1867) that was soon to lead to the discovery
of Neptune and which is still with us today with black holes, MACHOs and dark
matter. Theoretical analyses
by Safford in America and Auwers in Europe (both in their twenties) coincided
with the discovery in 1862 of Sirius B by Alvan Clark and his son Alvin Graham
Clark in Cambridge, Massachusetts.
The Clarks used their just-completed 18 ½-inch 'object glass', which
can be seen today in Chicago's Adler Planetarium.
It
was four years later that Otto Struve in Russia realized that the 10-magnitdue
brightness differences between Sirius A and Sirius B implied that the latter
was of a very different physical constitution. In a particularly masterful section of his book, Holberg
goes on to outline the recognition of the existence of giant and dwarf stars in
the first decades of the 20th century, and the realization by
Britain's foremost astrophysicist, Arthur Eddington, that Sirius B (and 40
Eridani B) had to be much dwarfer than dwarf. The snappy term 'white dwarf' coined by the Dutch astronomer
Willem Luyten is thus a misnomer.
White dwarfs such as Sirius B are incredibly compact and dense, "made of
a material 2000 times denser than platinum", as Eddington put it. The application of the new theory
of quantum mechanics showed that such densities were possible if the atoms were
completely ionized. But when the
Indian physicist Subramanyan Chandrasekhar added in special relativity, he
obtained the surprising result that increasing mass made a white dwarf smaller,
with the radius shrinking to zero for a white dwarf of about 1.4 solar masses. The clash with Eddington, who refused
to accept the reality of the 'Chandrasekhar limit' is the stuff of legend; but
suffice it to say that this limit was the work cited when Chandrasekhar shared
the Nobel Prize in Physics in 1983.
Eddington
nevertheless accepted the compact ness of Sirius B should result in a large
gravitational redshift in the object's spectrum - and an observational test of
general relativity - but it was only in 1971 that a convincing measurement was
finally obtained by the Americans Greenstein, Oke and Shipman, It is now
recognized that the gravitational redshift is not so much a test of general
relativity as of the more primitive concept of the equivalence between
gravitational and inertial mass.
Taking
a different tact, Holberg moves on to some mysteries associated with Sirius
such as the redness claimed by Ptolemy and its binary nature supposedly known
to the Dogon tribe in West Africa.
(To your reviewer, information from missionaries and linguistic
misunderstanding seem the almost-certain explanation of the Dogon story.) In the 1990s the Sirius-inspired Order
of the Solar Temple scam-cum-sect culminated in 174 deaths in Canada and
Europe.
In
the final chapters Holberg explains how the uncertainties in the measured
physical properties of Sirius A and B have been reduced to the present percent
level. (Much of this work has been
done by Holberg himself, who is a researcher at the Lunar and Planetary
Laboratory in Tucson.)
Finally the future evolution of the Sirius system is outlined with its
ultimate fate as a pair of ever-cooling white dwarfs.
I
thoroughly recommend this book as an instructive and entertaining read (Holberg
is good at the apposite analogy), and as one that discusses the early 20th-century
advances in astrophysics, which are often ignored in popular books, but
underlie our modern understanding of stars.
6
rue Saint Louis, 56000 Vannes, France
Southern Arizona Authors
The Arizona Daily Star - Aug.
2, 2007
By J. C. Martin
Jay
Holberg, senior research scientist
as the University of Arizona's Lunar and Planetary Laboratory, has spent the
last 20 years making room in his life for a white dwarf star known as Sirius,
the Dog Star.
"Sirius:
Brightest Diamond in the Night Sky"
(Springer/Praxis, $29.95) is a compilation of Holberg's remarkable findings. His persistent investigation follows
the star's saga from its earliest importance in ancient Egypt, through Greece
and Rome, to a small remote present-day African tribe in Mali. Sirius, a scant 8.6 light-years from
Earth, becomes visible again in Tucson in time for the Dog Days of August (a
Roman concept). It can be seen in
the very early mornings in the south east sky. It's bright enough to be visible just before sunrise. By late November, it will be
shrinking in the night sky.
Choice Reviews 2007 September (Choice
Magazine)
Sirius,
the brightest star in the night sky, has been of human interest at least since
early Egyptian priests watched for its heliacal rising as a sign that the Nile
would soon flood and fertilize the fields. Holberg, a scientist at the Lunar
and Planetary Laboratory at the Univ. of Arizona, Tucson, begins with the
ancient mythology and lore of Sirius, the Dog Star, and continues through the
history of stellar astronomy using the search for understanding Sirius as a guide.
He thoroughly explores stories that have turned out to be ill founded, such as
that Sirius was red in olden times. A modern cult's unfortunate belief that
their group suicide would send them to a blissful existence in the Sirius
system did indeed lead to mass suicide and murder. About 160 years ago, a
binary partner to Sirius A was predicted from its motion and found to be a
dimly seen white dwarf, Sirius B. The last chapters focus on the immense
increase in scientific understanding of the Sirius binary system that has been
achieved by using spacecraft and orbiting telescopes. Ample bibliography for
further investigation. Summing Up: Recommended. General readers; lower-division
undergraduates through faculty.
Copyright
2007 American Library Association.