Tycho's Nova
Tycho's Nova Summary
[Updated 11/12/07]
The Urantia Book states that "The most recent of the
major cosmic eruptions . . . was the extraordinary double star
explosion, the light of which reached [Earth] in A.D. 1572.
This conflagration was so intense that the explosion was
clearly visible in broad daylight." The explosion to which
The Urantia Book refers has come to be known as Tycho
Brahe's Nova. It was not until several decades after The
Urantia Book was published that astronomers determined
that, in all likelihood, a double (or binary) star
relationship, in which one star eventually accretes a critical
amount of matter from the other star, is responsible for the
explosion of this supernova. In 2004 researchers announced
that they believe they have discovered the remnant of the
companion star that gave rise to this explosion.
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Tycho's Nova: Class C Report
[Updated 11/12/07]
On the one hand, The Urantia Book gives some very specific
information about Tycho's Nova, and it required significant
technological advances and the development of complex scientific
analysis to corroborate The Urantia Book's assertion. It took
decades after The Urantia Book's publication in 1955 for
astronomers to catch up, and there was not speculation in the
scientific community either way about Tycho's Nova having a double
star origin prior to 1955.
On the other hand, this is a single-issue topic. The Urantia
Book makes just one statement on this specific subject.
Additionally, there can be no direct observation of the assertion
that a double star system gave rise to the supernova; once a
supernova occurs the opportunity to observe it is gone and Tycho's
Nova occurred hundreds of years ago, long before we had the
technology to directly observe whether it originated as a double
star. Therefore, forensic analysis is required to make assertions
about its origin.
Tycho's Nova Report
Prepared by Chris Halvorson, PhD and Halbert Katzen, JD
with special thanks to Phil Calabrese, PhD [Updated 02/18/08]
Most of the reports at UBtheNEWS involve corroborations of
information found in the middle third of The Urantia Book,
The History of Urantia [Earth], where it recounts the history
of our planet. This report, however, relates to a comment made
earlier in the book, which extensively describes aspects of our
"local universe," our local section of the galaxy. Chapter 41,
Physical Aspects of the Local Universe, makes the following
comments about suns in Section 3, Our Starry Associates:
When suns that are too large are thrown off a
nebular mother wheel, they soon break up or form double stars. All
suns are originally truly gaseous, though they may later
transiently exist in a semiliquid state. When your sun attained
this quasi-liquid state of supergas pressure, it was not
sufficiently large to split equatorially, this being one type of
double star formation.
When less than one tenth the size of your sun,
these fiery spheres rapidly contract, condense, and cool. When
upwards of thirty times its size-rather thirty times the gross
content of actual material-suns readily split into two separate
bodies, either becoming the centers of new systems or else
remaining in each other's gravity grasp and revolving about a
common center as one type of double star.
The most recent of the major cosmic eruptions in
Orvonton [a part of the universe described in The Urantia
Book that is much larger than our local universe and in which
our local universe is located] was the extraordinary double star
explosion, the light of which reached Urantia in A.D. 1572. This
conflagration was so intense that the explosion was clearly
visible in broad daylight. (Urantia Book
41:3.3-5)1
In order to appreciate how this statement, published in The
Urantia Book in 1955, was ahead of science, one needs to acquire
both a general understanding of how the science has developed
regarding supernovae and a specific understanding of how this
history of science relates to Tycho's Nova, the supernova explosion
of 1572 to which The Urantia Book refers. But, before
learning about the history of supernovae in general and Tycho's Nova
in particular, we will start with defining what a double star is.
The following quotes from Wikipedia provide a basic description of a
double star and indicate how "double" and "binary" are used
interchangeably in reference to this occurrence:
A double star is when two stars appear close to
each other as seen from Earth.
There are two kinds of double star: visual
binaries and optical binaries. Visual binaries are considered to
be a true binary star system and lie close enough together in
space to interact gravitationally such that the stars orbit each
other. Optical binaries (aka optical doubles), on the other hand,
are two stars that only appear to be close together, and are
actually separated by a great distance in space and are not
gravitationally bound to each other.2
A binary star is a stellar system consisting of
two stars orbiting around their center of mass. For each star, the
other is its companion star. . .
It is believed that a quarter to half of all
stars are in binary systems, with as many as 10% of these systems
containing more than two stars (triples, quadruples,
etc.).3
Advances in the quality and types of telescopes used to observe
the universe have allowed astronomers to better appreciate the
frequency of binary stars. These developments cover the time period
before and after The Urantia Book was published. At the time
of publication the frequency of binary star systems was not thought
to be as high as it is today. This change in our appreciation for
the frequency of binary systems has occurred because many binary
systems could not be identified until more advanced technologies
made it possible to recognize them as such.
Similarly, there have been changes to the classification models
of supernovae that span the time period before and after
publication. The original classification system of supernovae had to
do with brightness and other energy emanations.
Supernovae are classified based on the presence
or absence of certain features in their optical spectra taken near
maximum light. They are broadly divided into 4 main Types, the
naming convention of which only makes sense in historical
context.
Supernovae were first categorized in 1941 when
Rudolph Minkowski recognized that at least 2 different types
existed, those that showed hydrogen (H) in their spectra: Type II,
and those that did not: Type I. In the mid-1980s as the rate of
supernova discoveries increased and data quality improved, Type I
supernovae were further sub-divided based on the presence or
absence of silicon (Si) and helium (He) in their spectra. Type Ia
supernovae contain an obvious Si absorption at 6150 Angstoms
[angstroms], Type Ib have no Si but show He in emission, and Type
Ic display neither Si nor He. It was also discovered that while
Type Ia supernovae could be found anywhere and in any type of
galaxy, Type Ib and Type Ic supernovae occurred primarily in
populations of massive stars, similar to Type IIs.
We now know that Type II, Type Ib and Type Ic
supernovae result from the core-collapse of massive stars, while
Type Ia supernovae are the thermonuclear explosions of white
dwarfs. Even so, and to the confusion of many, astronomers
continue to use the nomenclature tied to the original Minkowski
types to classify supernovae.4
CLASSIFICATIONS OF SUPERNOVAE
The classifications of supernovae into groups that originate from
single and double star systems did not occur until after 1955. This
fact is referenced by Wikipedia in the following history of our
developing appreciation for the nature of supernovae:
The true nature of the supernova remained obscure
for some time. Observers slowly came to recognize a class of stars
that undergo long-term periodic fluctuations in luminosity. Both
John Russell Hind in 1848 and Norman Pogson in 1863 had charted
stars that underwent sudden changes in brightness. However these
received little attention from the astronomical community. In
1866, however, William Higgins made the first spectroscopic
observations of a nova, discovering lines of hydrogen in the
unusual spectrum of the recurrent nova T Coronae Borealis. Higgins
proposed a cataclysmic explosion as the underlying mechanism, and
his efforts drew interest from other astronomers.
In 1885, a nova-like outburst was observed in the
direction of the Andromeda galaxy by Ernst Hartwig in Estonia. S
Andromedae increased to 6th magnitude, outshining the entire
nucleus of the galaxy, then faded in a manner much like a nova.
However, in 1917, George W. Ritchey measured the distance to the
Andromeda galaxy and discovered it lay much further than had
previously been thought. This meant that S Andromedae, which did
not just lie along the line of sight to the galaxy but had
actually resided in the nucleus, released a much greater amount of
energy than was typical for a nova.
Early work on this new category of nova was
performed during the 1930s by Walter Baade and Fritz Zwicky at
Mount Wilson Observatory. They identified S Andromedae, what they
considered a typical supernova, as an explosive event that
released radiation approximately equal to the Sun's total energy
output for 107 years. They decided to call this new class of
cataclysmic variables super-novae, and postulated that the energy
was generated by the gravitational collapse of ordinary stars into
neutron stars.
Although supernova[e] are relatively rare events,
occurring on average about once a century in the Milky Way,
observations of distant galaxies allowed supernovae to be
discovered and examined more frequently. The first spectral
classification of these distant supernova[e] was performed by
Rudolph Minkowski in 1941. He categorized them into two types,
based on whether or not lines of the element hydrogen appeared in
the supernova spectrum. Zwicky later proposed additional types
III, IV and V, although these are no longer used and now appear to
be associated with single peculiar supernova types. Further
sub-division of the spectra categories resulted in the modern
supernova classification scheme.
In the aftermath of the Second World War, Fred
Hoyle worked on the problem of how the various observed elements
in the universe were produced. In 1946 he proposed that a massive
star could generate the necessary thermonuclear reactions, and the
nuclear reactions of heavy elements were responsible for the
removal of energy necessary for a gravitational collapse to occur.
The collapsing star became rotationally unstable, and produced an
explosive expulsion of elements that were distributed into
interstellar space. The concept that rapid nuclear fusion was the
source of energy for a supernova explosion was developed by Hoyle
and William Fowler during the 1960s.
The modern standard model for Type Ia supernova[
] explosions is founded on a proposal by Whelan and Iben in 1973,
and is based upon a mass-transfer scenario to a degenerate
companion star. In particular, the light curve of SN 1972e in NGC
5253, which was observed for more than a year, was followed long
enough to discover that after its broad "hump" in brightness, the
supernova faded at a nearly constant rate of about 0.01 magnitudes
per day. Translated to another system of units, this is nearly the
same as the decay rate of cobalt-56 (56Co), whose half-life is 77
days. The degenerate explosion model predicts the production of
about a solar mass of nickel-56 (56Ni) by the exploding star. The
56Ni decays with a half-life of 6.8 days to 56Co, and the decay of
the nickel and cobalt provides the energy radiated away by the
supernova late in its history. The agreement in both total energy
production and the fade rate between the theoretical models and
the observations of 1972e led to rapid acceptance of the
degenerate-explosion model.5
The statement above about how "The modern standard model for Type
Ia supernova[ ] explosions is founded on a proposal by Whelan and
Iben in 1973, and is based upon a mass-transfer scenario to a
degenerate companion star," indicates that the assertion made by
The Urantia Book in 1955 that Tycho's Nova had a double star
origin was about twenty years ahead of its time.
In the lead up to providing information on some of the more
recent research that indicates astronomers may have found Tycho's
companion star, researchers with the Isaac Newton Group of
Telescopes in a 2005 article called The Search for the Companion
Star of Tycho Brahe's 1572 Supernova give us another look at the
development of the theory that all Type Ia supernovae have a double
star origin:
In recent years, type Ia supernovae (SNe Ia) have
been used successfully as cosmological probes of the Universe
(Riess et al., 1998; Perlmutter et al., 1999). However, the nature
of their progenitors has remained somewhat of a mystery. It is
widely accepted that they represent the disruption of a degenerate
object, but there are also numerous progenitor models (see for
instance Ruiz-Lapuente, Canal, Isern, 1997a, for a review), but
most of these have serious theoretical/observational problems or
do not appear to produce sufficient numbers to explain the
observed frequency of SNe Ia in our Galaxy.
Hoyle and Fowler (1960) described how a white
dwarf, a common end-point in the evolution of low- and
intermediate- mass stars, could become a powerful fusion bomb if
its interior temperature rose from about 2 x 108 to 5 x
108 K. They anticipated that this type of explosion
could well correspond to the class of objects identified by
Minkowski (1941), called supernovae of type I and much later
renamed type Ia. These supernovae are characterized by their
spectral signatures and are the brightest observable stellar
explosions.
But, how can such high temperatures
(>108 K) be attained in the usually cold degenerate
cores of white dwarfs? A natural way to heat white dwarfs up is by
the accretion of material from a stellar companion. If the white
dwarf grows in mass by taking material from a donor star, its
central density and temperature rise, and it can achieve the
critical condition near 1.4 solar masses, the so-called
Chandrasekhar mass. The binary path is found to be the easiest
physical way to give rise to bare white dwarfs exploding in large
enough numbers to account for those supernovae. The single-star
models were both physically and statistically unsuccessful.
Recently, new momentum has been given to the study of possible
evolutionary paths to explosion. Observational efforts with
specific goals have been set up to clarify the issue by
contrasting the models with empirical
evidence.6
Having established that it was not until after 1955 that the
scientific community came to accept that all Type Ia supernovae have
a double star origin, we now turn our attention to the history of
the classification of Tycho's Nova as Type Ia. In a 1945 article W.
Baade put forth the following analysis, classifying Tycho's Nova as
a Type I supernova:
The light-curve of the nova of 1572, derived from
Tycho's observations, shows that the star was a supernova of type
I which reached at maximum the apparent magnitude of -4.0.
The fact that no expanding shell can be detected
at the place where the supernova flared up indicates that the
excitation provided by the stellar remnant is insufficient. This,
in turn, suggests that the star is much more advanced toward the
final white-dwarf state than are the stellar remnants of the
supernovae of A.D. 1054 and 1604.
It has been pointed out in a previous paper
(W.Baade, Mt. W. Conlr., No. 600; Ap.J., 88, 285, 1938) that B
Cassiopeiae, the bright nova of 1572, was undoubtedly a supernova
because of its amplitude, which exceeded 22 mag. The recent
recognition of two types of supernovae makes it desirable to
decide whether the star was a supernova of type I or type II. The
light-curve of the nova, derived in the present paper, clearly
indicates a supernova of type I. Because it throws new light on
the final state of a supernova, B Cas is of particular
interest.
It is impossible at present to press the search
for the stellar remnant of B Cas to still fainter limits, since
the nova, on account of its high declination, cannot be reached
with the 100-inch telescope. However, there is every prospect that
it will be found when the 200-inch telescope comes into
operation.7
The existence of double stars was established prior to 1955.
Determining that Tycho's Nova should be classified as Type I
occurred prior to 1955 based on the observational data provided by
Tycho Brahe. However, relocating and identifying Tycho's Nova as
having a binary origin did not occur until after 1955.
The process of first identifying the location of the remnant of
Tycho's Nova and then placing it in the category of supernovae with
a double star origin began in 1952 through the use of radio wave
detection. Identification through optical recognition did not occur
until after 1955. The quote below from Nature magazine,
submitted July 14 by R. Hanbury
Brown & C. Hazard for the August 1952 edition,
indicates that the radio waves from Tycho's Nova had not yet been
detected. The one following it shows that by the end of the year the
discovery of its radio waves had been made.
SINCE the discovery of localized sources of
extraterrestrial radio-frequency radiation in 1948, surveys have
been carried out over the whole sky, and the positions and
intensities of about one hundred sources are now known. Although a
few of these sources have been identified with extra-galactic
nebulae, it is generally considered that the majority must lie
within the Galaxy with a distribution, and perhaps a density,
similar to that of the common visual stars. However, it has not
yet been possible to associate the radio sources with any class of
visual objects in the Galaxy, and in only one instance has an
identification been made, namely, the identification of a source
in Taurus with the Crab nebula. As the Crab nebula is believed to
be the remnant of the supernova of 1054, it is to be expected that
the remnants of other supernovae are also sources of radio
radiation. The other supernovae known to have occurred in the
Galaxy are those of 1572 and 1604, but the published surveys show
no radio source in either of these positions.8
The . . . remnant is the result of the supernova
explosion in 1572 which was studied by Tycho Brahe . . . and has
since been called Tycho's nova, otherwise know as Nova B
Cassiopia. The remnant was first discovered in 1952 by Hanbury
Brown and Hazard as a strong radio source. Subsequently, Minkowski
found the optical remnant associated with the radio source.
Tycho's nova is now known also as a strong source of X-ray
emission. Analyzing the old records of this nova, Baade concluded
that at maximum it had an apparent visual magnitude of -4, its
light curve corresponding to that of a Type I
supernova.9
Sol Company on their SolStation.com website provides this
overview:
The remnant of the supernova was not found until
1952, with the help of the Jodrell Bank radio telescope (Brown and
Hazard, 1953), catalogued as radio source 3C 10. Shortly
thereafter, faint optical wisps in the same location were
discovered using the 200-inch telescope at Mt. Palomar during the
1960s, when an extremely faint nebulosity was identified on photo
plates. The gas shell is now expanding at about 5,600 miles (9,000
km) per second -- much more than the Crab Nebula's expansion speed
of about 600 miles (1,000 km) per second -- and has grown to about
3.7 arc-minutes -- around 24 light-years (ly) wide according to
one estimate. However, no central point source has been detected
within the Tycho supernova remnant (SNR), which is consistent with
other evidence that the SNR was created by a Type-Ia
supernova.10
Additional history related to Tycho's Nova is summarized in
Wikipedia:
SN 1572 or Tycho's Nova was a supernova in the
constellation Cassiopeia, one of the eight supernovae visible to
the naked eye. It was first observed on November 11, 1572 by the
Danish scientist Tycho Brahe, when it was brighter than Venus. In
March 1574 its brightness fell below visibility with the naked
eye.
Tycho Brahe may not have been the first to notice
the supernova; it was probably Wolfgang Schuler, who first saw it
on November 6, 1572. The Italian astronomer Francesco Maurolico
may also have spotted it before Tycho.
The supernova remnant was discovered in the 1960s
by scientists at the Mount Palomar telescope as a very faint
nebula. It was later photographed by a telescope on the
international ROSAT spacecraft. The supernova was probably of Type
Ia, in which a white dwarf star has accreted matter from a
companion until it reaches the Chandrasekhar limit and explodes.
This type of supernova does not typically create the spectacular
nebula more typical of Type II supernovas, such as SN 1054 which
created the Crab Nebula. A shell of gas is still expanding from
its center at about 9,000 km/s.
In October 2004, a letter in Nature reported the
discovery of a G2 star, similar in type to our own Sun. It is
thought to be the companion star that contributed mass to the
white dwarf that ultimately resulted in the supernova. A
subsequent study, published in March 2005, revealed further
details about this star: labeled Tycho G, it was likely a main
sequence star or subgiant prior to the explosion, but had some of
its mass stripped away and its outer layers shock-heated from the
effects of the supernova. Tycho G's current velocity is perhaps
the strongest evidence that it was the companion star to the white
dwarf, as it is traveling at a rate of 136 km/s, which is more
than forty times faster than the mean velocity of other stars in
its stellar neighbourhood.11
X-ray image of the SN 1572 remnant
Research reports from 2004 and 2005 indicate astronomers believe
they have found the companion. These recent developments, nearly
fifty years after The Urantia Book's assertion that Tycho's
Nova originated as a double star, lend additional support to the
previously and widely held belief by astronomers that Tycho's Nova
did in fact have a double star origin.
Researchers with the Isaac Newton Group explain the new findings
in this way:
A particularly conclusive test would be the
detection of a companion star that has survived the supernova
explosion in the supernova remnant. At present the detection of a
surviving companion would only be feasible in our Galaxy. The
supernova of the millennium, the Lupus supernova (also designated
SN 1006 after the year of its appearance) was a supernova of this
type. The supernova discovered by Tycho Brahe, SN 1572, was also
of this type. Both are the only unambiguous type Ia supernovae
observed in our Galaxy during the last thousand
years.12
Observable Consequences on the Companion
Star
The predictions of how the companion star would
look after the impact of the supernova ejecta, if there is any
companion, were investigated by Canal, Méndez and Ruiz-Lapuente
(2001), depending on the type of star it actually is. Among other
features, the surviving companion star should have a peculiar
velocity with respect to the average motion of the other stars at
the same location in the Galaxy -mainly due to disruption of the
binary- detectable through proper-motion and radial velocity
measurements, and perhaps also signs of the impact of the
supernova ejecta. The latter can be twofold. First, mass should
have been stripped from the companion and thermal energy injected
into it, possibly leading to the expansion of the stellar envelope
that would make the star have a lower surface gravity. Second,
depending on the interaction with the ejected material, the
surface of the star could be contaminated by the slowest- moving
ejecta made of Fe and Ni isotopes. If the companion's stellar
envelope is radiative, such a contamination could be detectable
through abundance measurements.
The Search for the Companion Star of SN
1572
Tycho Brahe's supernova (SN 1572) is one of the
only two supernovae observed in our Galaxy that are thought to
have been of Type Ia as revealed by the light curve
(Ruiz-Lapuente, 2004), radio emission (Baldwin et al., 1957) and
X-ray spectra (Hughes et al., 1995).
The field that contained Tycho's supernova,
relatively devoid of background stars, is favorable for searching
for any surviving companion. With a Galactic latitude b=+1.4°,
Tycho's supernova lies 59-78 pc above the Galactic plane. The
stars in that direction show a consistent pattern of radial
velocities with a mean value of -30 km/s at 3 kpc. The star most
likely to have been the mass donor of SN 1572 has to show a
multiple coincidence: being at the distance of SN 1572, showing an
unusual motion in comparison to the stars at the same location,
having stellar parameters consistent with being struck by the
supernova explosion and lying near the remnant centre.
The distance to SN 1572 inferred from the
expansion of the radio shell and by other methods lies around 3
kpc. Such a distance, and the light-curve shape of SN 1572, are
consistent with it being a normal Type Ia supernova in luminosity,
like those commonly found in cosmological searches (Ruiz-Lapuente,
2004).13
Our search for the binary companion of Tycho's
supernova has excluded giant stars. It has also shown the absence
of blue or highly luminous objects as post-explosion companion
stars. One of the stars, Tycho G of our sample, show[s] a high
peculiar velocity (both radial and tangential velocities), lies
within the distance range for the explosion of SN 1572, and its
type, G2IV, fits the post-explosion profile of a Type Ia supernova
companion whose position in the Hertzsprung-Russell diagram is
untypical for a standard subgiant.
If Tycho G is the companion star of SN1572, its
overall characteristics imply that the supernova explosion
affected the companion mainly through the kinematics. Therefore, a
star very similar to our Sun but of a slightly more evolved type
would have been the mass donor that triggered the explosion of
Type Ia SN1572, connecting the supernova explosion to the family
of cataclysmic variables.
The results of this research, led by Pilar
Ruiz-Lapuente of the University of Barcelona, was published in the
October 28 issue of Nature. The co-authors are Fernando Comeron
(ESO), Javier Méndez (University of Barcelona and ING), Ramón
Canal (University of Barcelona), Stephen Smartt (IoA, Cambridge),
Alex Filippenko (University of California, Berkeley), Robert
Kurucz (Harvard-Smithsonian Centre for Astrophysics), Ryan
Chornock and Ryan Foley (University of California, Berkeley),
Vallery Stanishev (Stockholm University), and Rodrigo Ibata
(Observatory of Strasbourg).14
The assertion by The Urantia Book in 1955 regarding the
double star origin of SN 1572, Tycho's Nova, was nearly twenty years
ahead of the contemporary appreciation by the scientific community
that supernovae of this kind originate as double stars. The research
reported in 2004 and 2005 further establishes that Tycho's Nova has
been appropriately identified as a Type Ia supernova.
- Citations to The Urantia Book are provided in the above
format. In the present case, 41 refers to the chapter (referred to
as a "Paper" in The Urantia Book); 3 refers to the section;
and 3-5 refers to the paragraphs.
- http://en.wikipedia.org/wiki/Double_star
- http://en.wikipedia.org/wiki/Binary_star
- http://astronomy.swin.edu.au/cosmos/S/Supernova+Classification
- http://en.wikipedia.org/wiki/History_of_supernova_observation
- http://www.ing.iac.es/PR/newsletter/news9/science7.html
- B Cassiopeiae as a Supernova of Type I (Contributions from the
Mount Wilson Observatory, Carnegie Institution of Washington, No.
711.), W. Baade, Mount Wilson Observatory, Received June 13, 1945
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1945ApJ...102..309B&letter=.&classic=YES&defaultprint=YES&whole_paper=YES&page=309&epage=309&send=Send+PDF&filetype=.pdf
- http://www.nature.com/nature/journal/v170/n4322/abs/170364a0.html
- An Introduction to Astrophysics by Baidyanath Basu, p. 262
- http://www.solstation.com/x-objects/tycho-s.htm
- http://en.wikipedia.org/wiki/SN_1572
- http://www.ing.iac.es/PR/newsletter/news9/science7.html
- http://www.ing.iac.es/PR/newsletter/news9/science7.html
- http://www.ing.iac.es/PR/newsletter/news9/science7.html
 Tycho's Nova Raw Data
Urantia Book quotes:
41:3.3 When suns that are too large are thrown off a nebular
mother wheel, they soon break up or form double stars. All suns are
originally truly gaseous, though they may later transiently exist in
a semiliquid state. When your sun attained this quasi-liquid state
of supergas pressure, it was not sufficiently large to split
equatorially, this being one type of double star formation.
41:3.4 When less than one tenth the size of your sun, these fiery
spheres rapidly contract, condense, and cool. When upwards of thirty
times its size-rather thirty times the gross content of actual
material-suns readily split into two separate bodies, either
becoming the centers of new systems or else remaining in each
other's gravity grasp and revolving about a common center as one
type of double star.
41:3.5 The most recent of the major cosmic eruptions in Orvonton
was the extraordinary double star explosion, the light of which
reached Urantia in A.D. 1572. This conflagration was so intense that
the explosion was clearly visible in broad daylight.
http://www.nature.com/nature/journal/v431/n7012/abs/nature03006.html
Brief summary
http://www.solstation.com/x-objects/tycho-s.htm
best summary and link resource
http://www.nrao.edu/imagegallery/php/level2a.php?class=Galactic_Sources&subclass=Supernova%20Remnants
http://adsabs.harvard.edu/cgi-bin/nph-basic_connect?qsearch=tycho&version=1
link to many scientific reports on Tycho
http://www.nature.com/nature/journal/v170/n4322/abs/170364a0.html
1952 article, not yet discovered in August 1952
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1945ApJ...102..309B&letter=.&classic=YES&defaultprint=YES&whole_paper=YES&page=309&epage=309&send=Send+PDF&filetype=.pdf
1945 article
http://www.noao.edu/outreach/aop/observers/casstemp.html
rediscovered in 1952, National Optical Astronomy Observatory
http://en.wikipedia.org/wiki/SN_1572
http://en.wikipedia.org/wiki/Double_star
http://www.astro.rug.nl/~onderwys/ACTUEELONDERZOEK/JAAR2001/jakob/aozindex.html
explanation of Supernova Type 1a
http://deposit.ddb.de/cgi-bin/dokserv?idn=979066697&dok_var=d1&dok_ext=pdf&filename=979066697.pdf
http://history.nasa.gov/SP-466/ch9.htm
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v497n2/37187/37187.html
http://www.sciencedaily.com/releases/2005/09/050923075505.htm
http://hubblesite.org/newscenter/archive/releases/2004/34/text/
Announcement of companion star discovery in 2004
http://books.google.com/books?id=1w5f5Po4XV8C&pg=PA262&lpg=PA262&dq=tycho+brahe+rediscovered+1952&source=web&ots=8Phwz7Wgs_&sig=OiNiaG2S1HcYovI8IC8Oc2dtSPA#PPR1,M1
historical references
http://adsabs.harvard.edu/abs/1984AZh....61.1125P
shows no binary classification in early 80's
http://astronomy.swin.edu.au/cosmos/S/Supernova+Classification
supernova classification system
http://www.ubthenews.com/topics/>http://www.ing.iac.es/PR/newsletter/news9/science7.html</a>%20more%20indepth,%20Isaac%20Newton%20Group%20of%20Telescopes,%20text:<br%20/><br%20/><a%20href=
http://astronomy.swin.edu.au/cosmos/T/Type+Ia+Supernova+Progenitors
http://heasarc.gsfc.nasa.gov/docs/objects/snrs/snrstext.html#intro
http://arxiv.org/pdf/astro-ph/0309009
http://adsabs.harvard.edu/full/1993ApJ...413...67V
van den Bergh 1993:
The Astrophysical Journal, 413: 67-69, 1993
August 10
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