History of supernova observation
Encyclopedia
Common Era
Common Era ,abbreviated as CE, is an alternative designation for the calendar era originally introduced by Dionysius Exiguus in the 6th century, traditionally identified with Anno Domini .Dates before the year 1 CE are indicated by the usage of BCE, short for Before the Common Era Common Era...
, when supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
SN 185
SN 185
SN 185 was a supernova which appeared in the year 185 AD, near the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at RA Dec , in Circinus. This "guest star" was observed by Chinese astronomers in the Book of Later Han, and may have been recorded in Roman...
appeared, the oldest appearance of a supernova recorded by humankind. Several additional supernovae within the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy have been recorded since that time, with SN 1604
SN 1604
Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a supernova that occurred in the Milky Way, in the constellation Ophiuchus. , it is the last supernova to have been unquestionably observed in our own galaxy, occurring no farther than 6 kiloparsecs or about...
being the most recent supernova to be observed in this galaxy
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
.
Since the development of the telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
, the field of supernova discovery has expanded to other galaxies. These occurrences provide important information on the distances of galaxies. Successful models of supernova behavior have also been developed, and the role of supernova in the star formation process is now increasingly understood.
Early history
The supernova explosion that formed the Gum NebulaGum Nebula
Gum Nebula is an emission nebula that can be found in the southern constellations Vela and Puppis. It lies roughly 400 parsecs from the Earth. Hard to distinguish, it is believed to be the greatly expanded remains of a supernova that took place about a million years ago...
most likely occurred 10,000–20,000 years ago. In 1972, NASA astronomers suggested that inhabitants of the southern hemisphere may have witnessed this explosion and recorded it symbolically. A year later, archaeologist George Michanowsky recalled some incomprehensible ancient markings in Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
that were left by Native Americans
Indigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
. The carvings showed four small circles flanked by two larger circles. The smaller circles resemble stellar groupings in the constellations Vela
Vela (constellation)
Vela is a constellation in the southern sky. Its name is Latin for the sails of a ship, and it was originally part of a larger constellation, the ship Argo Navis, which was later divided into three parts, the others being Carina and Puppis.-Stars:...
and Carina
Carina (constellation)
Carina is a constellation in the southern sky. Its name is Latin for the keel of a ship, and it was formerly part of the larger constellation of Argo Navis until that constellation was divided in three.-Stars:...
. One of the larger circles may represent the star Capella
Capella
Capella can refer to:* Capella , a bright star in the constellation of Auriga* Capella , an impact crater on the Moon* Capella, Queensland, a small town in Central Queensland* Capella Island, a minor island of the U.S...
. As other circle is located near the position of the supernova remnant, George Michanowsky suggested this may represent the supernova explosion as witnessed by the indigenous residents.
In 185 CE, Chinese astronomers
Chinese astronomy
Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...
recorded the appearance of a bright star in the sky, and observed that it took about eight months to fade from the sky. It was observed to sparkle like a star and did not move across the heavens like a comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
. These observations are consistent with the appearance of a supernova, and this is believed to be the oldest confirmed record of a supernova event by humankind. SN 185
SN 185
SN 185 was a supernova which appeared in the year 185 AD, near the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at RA Dec , in Circinus. This "guest star" was observed by Chinese astronomers in the Book of Later Han, and may have been recorded in Roman...
may have also possibly been recorded in Roman
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....
literature, though no records have survived. The gaseous shell RCW 86 is suspected as being the remnant of this event, and recent X-ray studies show a good match for the expected age.
In 393 CE, the Chinese recorded the appearance of another "guest star"
Guest star (astronomy)
In Chinese astronomy, the term guest star refers to a star which has suddenly appeared visible in the place where no star had previously been observed and becomes invisible again after some time. The term is a literal translation from ancient Chinese astronomical records...
, SN 393, in the modern constellation of Scorpius
Scorpius
Scorpius, sometimes known as Scorpio, is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is . It lies between Libra to the west and Sagittarius to the east...
. Additional unconfirmed supernovae events may have been observed in 369 CE, 386 CE,
437 CE, 827 CE and 902 CE. However these have not yet been associated with a supernova remnant, and so they remain only candidates. Over a span of about 2,000 years, Chinese astronomers recorded a total of twenty such candidate events, including later explosions noted by Islamic, European, and possibly Indian and other observers.
The supernova SN 1006
SN 1006
SN 1006 was a supernova, widely seen on Earth beginning in the year 1006 AD; Earth was about 7,200 light-years away from the supernova. It was the brightest apparent magnitude stellar event in recorded history reaching an estimated -7.5 visual magnitude...
appeared in the southern constellation of Lupus
Lupus (constellation)
Lupus is a constellation in the southern sky. Its name is Latin for wolf. Lupus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations...
during the year 1006 CE. This was the brightest recorded star ever to appear in the night sky, and its presence was noted in China, Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
, Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....
, Italy, Japan and Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
. It may also have been noted in France, Syria
Syria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....
, and North America. Egyptian physician
Islamic medicine
In the history of medicine, Islamic medicine, Arabic medicine or Arabian medicine refers to medicine developed in the Islamic Golden Age, and written in Arabic, the lingua franca of Islamic civilization....
, astronomer
Islamic astronomy
Islamic astronomy or Arabic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age , and mostly written in the Arabic language. These developments mostly took place in the Middle East, Central Asia, Al-Andalus, and North Africa, and...
and astrologer Ali ibn Ridwan
Ali ibn Ridwan
Abu'l Hasan Ali ibn Ridwan Al-Misri was an Egyptian Muslim physician, astrologer and astronomer, born in Giza.He was a commentator on ancient Greek medicine, and in particular on Galen; his commentary on Galen's Ars Parva was translated by Gerardo Cremonese...
gave the brightness of this star as one-quarter the brightness of the Moon. Modern astronomers have discovered the faint remnant of this explosion and determined that it was only 7,100 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s from the Earth.
SN 1054
SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD, hence its name, and that lasted for a period of around two years. The event was recorded in multiple Chinese and Japanese documents and in one document from the Arab world...
was another widely-observed event, with Arab
Islamic astronomy
Islamic astronomy or Arabic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age , and mostly written in the Arabic language. These developments mostly took place in the Middle East, Central Asia, Al-Andalus, and North Africa, and...
, Chinese
Chinese astronomy
Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...
, and Japanese astronomers recording the star's appearance in 1054 CE. It may also have been recorded by the Anasazi as a petroglyph
Petroglyph
Petroglyphs are pictogram and logogram images created by removing part of a rock surface by incising, picking, carving, and abrading. Outside North America, scholars often use terms such as "carving", "engraving", or other descriptions of the technique to refer to such images...
. This explosion appeared in the constellation of Taurus
Taurus (constellation)
Taurus is one of the constellations of the zodiac. Its name is a Latin word meaning 'bull', and its astrological symbol is a stylized bull's head:...
, where it produced the Crab Nebula
Crab Nebula
The Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus...
remnant. At its peak, the luminosity of SN 1054 may have been four times as bright as Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
, and it remained visible in daylight for 23 days and was visible in the night sky for 653 days.
There are fewer records of supernova SN 1181
SN 1181
First observed between August 4 and August 6, 1181, Chinese and Japanese astronomers recorded the supernova now known as SN 1181 in eight separate texts....
, which occurred in the constellation Cassiopeia
Cassiopeia (constellation)
Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology, who boasted about her unrivalled beauty. Cassiopea was one of the 48 constellations listed by the 2nd century Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today...
just over a century after SN 1054. It was noted by Chinese and Japanese astronomers, however. The pulsar
Pulsar
A pulsar is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name...
3C58
3C58
3C58 or 3C 58 is a pulsar and surrounding synchrotron nebula within the Milky Way that is possibly associated with the supernova SN 1181. There are, however, signs that indicate that it could be several thousand years old, and thus not associated with that supernova...
may be the stellar relic from this event.
The Danish
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
astronomer Tycho Brahe
Tycho Brahe
Tycho Brahe , born Tyge Ottesen Brahe, was a Danish nobleman known for his accurate and comprehensive astronomical and planetary observations...
was noted for his careful observations of the night sky from his observatory on the island of Hven
Hven
Ven is a small Swedish island in the Öresund strait, between Scania and Zealand . It is situated in Landskrona Municipality, Skåne County. The island has 371 inhabitants and an area of . During the 1930s, the population was at its peak, with approximately 1,300 inhabitants...
. In 1572 he noted the appearance of a new star, also in the constellation Cassiopeia. Later called SN 1572
SN 1572
SN 1572 , "B Cassiopeiae" , or 3C 10 was a supernova of Type Ia in the constellation Cassiopeia, one of about eight supernovae visible to the naked eye in historical records...
, this
supernova was associated with a remnant during the 1960s.
A common belief in Europe during this period was the Aristotelian
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
idea that the world beyond the Moon and planets was immutable. So observers argued that the phenomenon was something in the Earth's atmosphere. However Tycho noted that the object remained stationary from night to night—never changing its parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...
—so it must lie far away. He published his observations in the small book De nova et nullius aevi memoria prius visa stella (Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "concerning the new (...) star") in 1573. It is from the title of this book that the modern word nova for cataclysmic variable stars is derived.
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy was SN 1604
SN 1604
Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a supernova that occurred in the Milky Way, in the constellation Ophiuchus. , it is the last supernova to have been unquestionably observed in our own galaxy, occurring no farther than 6 kiloparsecs or about...
, which was observed October 9, 1604. Several people noted the sudden appearance of this star, but it was Johannes Kepler
Johannes Kepler
Johannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...
who became noted for his systematic study of the object. He published his observations in the work De Stella nova in pede Serpentarii.
Galileo
Galileo Galilei
Galileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...
, like Tycho before him, tried in vain to measure the parallax of this new star, and then argued against the Aristotelian view of an immutable heavens. The remnant of this supernova was identified in 1941 at the Mount Wilson Observatory
Mount Wilson Observatory
The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...
.
Telescope observation
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 HindJohn Russell Hind
John Russell Hind FRS was an English astronomer.- Life and work :John Russell Hind was born in 1823 in Nottingham, the son of lace manufacturer John Hind, and was educated at Nottingham High School...
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. Finally, in 1866, English astronomer William Huggins
William Huggins
Sir William Huggins, OM, KCB, FRS was an English amateur astronomer best known for his pioneering work in astronomical spectroscopy.-Biography:...
made the first spectroscopic observations of a nova, discovering lines of hydrogen in the unusual spectrum of the recurrent nova T Coronae Borealis
T Coronae Borealis
T Coronae Borealis , informally nicknamed the Blaze Star, is a recurring nova in the constellation Corona Borealis. It normally has a magnitude of about 10, which is near the limit of typical binoculars. It has been seen to outburst twice, reaching magnitude 2.0 on May 12, 1866 and magnitude 3.0...
. Huggins 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
Andromeda Galaxy
The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the constellation Andromeda. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula in older texts. Andromeda is the nearest spiral galaxy to the...
by Ernst Hartwig
Ernst Hartwig
Carl Ernst Albrecht Hartwig was a German astronomer.He discovered a new star in M31 on August 20, 1885. This object was designated as supernova "S Andromedae". During the 1883 observation campaign of comet 6P/d'Arrest he found five NGC objects working at the Strasbourg Observatory...
in Estonia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...
. S Andromedae
S Andromedae
|- style="background-color: #A0B0FF;" colspan="3"| Database References|- bgcolor="#FFFAFA"| Simbad || |- bgcolor="#FFFAFA"| ||...
increased to 6th magnitude, outshining the entire nucleus of the galaxy, then faded in a manner much like a nova. In 1917, George W. Ritchey
George Willis Ritchey
George Willis Ritchey was an American optician and telescope maker and astronomer born at Tuppers Plains, Ohio....
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
Walter Baade
Wilhelm Heinrich Walter Baade was a German astronomer who worked in the USA from 1931 to 1959.-Biography:He took advantage of wartime blackout conditions during World War II, which reduced light pollution at Mount Wilson Observatory, to resolve stars in the center of the Andromeda galaxy for the...
and Fritz Zwicky
Fritz Zwicky
Fritz Zwicky was a Swiss astronomer. He worked most of his life at the California Institute of Technology in the United States of America, where he made many important contributions in theoretical and observational astronomy.- Biography :Fritz Zwicky was born in Varna, Bulgaria to a Swiss father....
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 star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...
s. The name super-novae was first used in a 1931 lecture at Caltech by Zwicky, then used publicly in 1933 at a meeting of the American Physical Society
American Physical Society
The American Physical Society is the world's second largest organization of physicists, behind the Deutsche Physikalische Gesellschaft. The Society publishes more than a dozen scientific journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than 20...
. By 1938, the hyphen had been lost and the modern name was in use.
Although supernovae 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 supernova detection patrol was begun by Zwicky in 1933. He was joined by Josef J. Johnson from Caltech in 1936. Using a 45-cm Schmidt telescope at Palomar observatory
Palomar Observatory
Palomar Observatory is a privately owned observatory located in San Diego County, California, southeast of Pasadena's Mount Wilson Observatory, in the Palomar Mountain Range. At approximately elevation, it is owned and operated by the California Institute of Technology...
, they discovered twelve new supernovae within three years by comparing new photographic plates to reference images of extragalactic regions.
In 1938, Walter Baade became the first astronomer to identify a nebula
Nebula
A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases...
as a supernova remnant
Supernova remnant
A supernova remnant is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way.There are two...
when he suggested that the Crab Nebula
Crab Nebula
The Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus...
was the remains of SN 1054
SN 1054
SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD, hence its name, and that lasted for a period of around two years. The event was recorded in multiple Chinese and Japanese documents and in one document from the Arab world...
. He noted that, while it had the appearance of a planetary nebula
Planetary nebula
A planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
, the measured velocity of expansion was much too large to belong to that classification. During the same year, Baade first proposed the use of the Type Ia supernova as a secondary distance indicator in 1938. Later, the work of Allan Sandage
Allan Sandage
Allan Rex Sandage was an American astronomer. He was Staff Member Emeritus with the Carnegie Observatories in Pasadena, California. He is best known for determining the first reasonably accurate value for the Hubble constant and the age of the universe.-Career:Sandage was one of the most...
and Gustav Tammann
Gustav Tammann
Gustav Andreas Tammann was the director of the Astronomical Institute of the University of Basel, Switzerland, European Space Agency member of the Space Telescope Advisory Team, and Member of Council of the European Southern Observatory. His research interests include supernovae and the...
helped refine the process so that Type Ia supernovae became a type of standard candle for measuring large distances across the cosmos.
The first spectral classification of these distant supernova was performed by Rudolph Minkowski
Rudolph Minkowski
Rudolph Minkowski was a German-American astronomer. His father was the physiologist Oskar Minkowski and his uncle was Hermann 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
Fred Hoyle
Sir Fred Hoyle FRS was an English astronomer and mathematician noted primarily for his contribution to the theory of stellar nucleosynthesis and his often controversial stance on other cosmological and scientific matters—in particular his rejection of the "Big Bang" theory, a term originally...
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
William Alfred Fowler
William Alfred "Willy" Fowler was an American astrophysicist and winner of the Nobel Prize for Physics in 1983. He should not be confused with the British astronomer Alfred Fowler....
during the 1960s.
The first computer-controlled search for supernovae was begun in the 1960s at Northwestern University
Northwestern University
Northwestern University is a private research university in Evanston and Chicago, Illinois, USA. Northwestern has eleven undergraduate, graduate, and professional schools offering 124 undergraduate degrees and 145 graduate and professional degrees....
. They built a 24-inch telescope at Corralitos Observatory
Corralitos Observatory
Corralitos Observatory was an astronomical observatory located near Las Cruces, New Mexico. It was built on the same property as the Organ Pass Observatory and was dedicated in 1961, serving as a remote satellite station of Dearborn Observatory, Northwestern University.In October 1965, a NASA...
in New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
that could be repositioned under computer control. The telescope displayed a new galaxy each minute, with observers checking the view on a television screen. By this means, they discovered 14 supernovae over a period of two years.
1970–1999
The modern standard model for Type Ia supernovaType Ia supernova
A Type Ia supernova is a sub-category of supernovae, which in turn are a sub-category of cataclysmic variable stars, that results from the violent explosion of a white dwarf star. A white dwarf is the remnant of a star that has completed its normal life cycle and has ceased nuclear fusion...
e 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
NGC 5253
NGC 5253 is an irregular galaxy in the constellation Centaurus. It was discovered by John Frederick William Herschel on 15 March 1787.-Galaxy group information:...
, 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
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
per day. Translated to another system of units
Units of measurement
A unit of measurement is a definite magnitude of a physical quantity, defined and adopted by convention and/or by law, that is used as a standard for measurement of the same physical quantity. Any other value of the physical quantity can be expressed as a simple multiple of the unit of...
, this is nearly the same as the decay rate of cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
-56 (56Co), whose half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
is 77 days. The degenerate explosion model predicts the production of about a solar mass of nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
-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.
Through observation of the light curves of many Type Ia supernovae, it was discovered that they appear to have a common peak luminosity. By measuring the luminosity of these events, the distance to their host galaxy can be estimated with good accuracy. Thus this category of supernovae has become highly useful as a standard candle for measuring cosmic distances. In 1998, the High-Z Supernova Search and the Supernova Cosmology Project discovered that the most distant Type Ia supernovae appeared dimmer than expected. This has provided evidence that the expansion of the universe may be accelerating.
Although no supernova has been observed in the Milky Way since 1604, it appears that a supernova exploded in the constellation Cassiopeia about 300 years ago, around the year 1667 or 1680. The remnant of this explosion, Cassiopeia A
Cassiopeia A
Cassiopeia A is a supernova remnant in the constellation Cassiopeia and the brightest astronomical radio source in the sky, with a flux density of 2720 Jy at 1 GHz. The supernova occurred approximately away in the Milky Way. The expanding cloud of material left over from the supernova is now...
—is heavily obscured by interstellar dust, which is possibly why it did not make a notable appearance. However it can be observed in other parts of the spectrum, and it is the currently the brightest radio source beyond our solar system.
Large Magellanic Cloud
The Large Magellanic Cloud is a nearby irregular galaxy, and is a satellite of the Milky Way. At a distance of slightly less than 50 kiloparsecs , the LMC is the third closest galaxy to the Milky Way, with the Sagittarius Dwarf Spheroidal and Canis Major Dwarf Galaxy lying closer to the center...
was observed within hours of its start. It was the first supernova to be detected through its neutrino
Neutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
emission and the first to be observed across every band of the electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
. The relative proximity of this supernova has allowed detailed observation, and it provided the first opportunity for modern theories of supernova formation to be tested against observations.
The rate of supernova discovery steadily increased throughout the twentieth century. In the 1990s, several automated supernova search programs were initiated. The Leuschner Observatory Supernova Search program was began in 1992 at Leuschner Observatory
Leuschner Observatory
Leuschner Observatory, originally called the Students' Observatory, is an observatory operated by the University of California, Berkeley. The observatory was built in 1886 on the Berkeley campus. For many years, it was directed by Armin Otto Leuschner, for whom the observatory was renamed in 1951...
. It was joined the same year by the Berkeley Automated Imaging Telescope program. These were succeeded in 1996 by the Katzman Automatic Imaging Telescope
Katzman Automatic Imaging Telescope
The Katzman Automatic Imaging Telescope is an automated telescope used in the search for supernovae.The KAIT is a computer-controlled reflecting telescope with a 76 cm mirror and a CCD camera to take pictures. It is located at the Lick Observatory near San Jose, California.KAIT can take close to...
at Lick Observatory
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, USA...
, which was primarily used for the Lick Observatory Supernova Search (LOSS). By 2000, the Lick program resulted in the discovery of 96 supernovae, making it the world's most successful Supernova search program.
In the late 1990s it was proposed that recent supernova remnants could be found by looking for gamma ray
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
s from the decay of titanium-44. This has a half-life of 90 years and the gamma rays can traverse the galaxy easily, so it permits us to see any remnants from the last millennium or so. Two sources were found, the previously discovered Cassiopeia A
Cassiopeia A
Cassiopeia A is a supernova remnant in the constellation Cassiopeia and the brightest astronomical radio source in the sky, with a flux density of 2720 Jy at 1 GHz. The supernova occurred approximately away in the Milky Way. The expanding cloud of material left over from the supernova is now...
remnant, and the RX J0852.0-4622
RX J0852.0-4622
RX J0852.0-4622 is a recently discovered supernova remnant. The remnant is located in the southern sky in the constellation Vela , and sits inside the much larger and older Vela Supernova Remnant...
remnant, which had just been discovered overlapping the Vela Supernova Remnant
Vela Supernova Remnant
The Vela supernova remnant is a supernova remnant in the southern constellation Vela. Its source supernova exploded approximately 11,000-12,300 years ago...
This remnant (RX J0852.0-4622) had been found in front (apparently) of the larger Vela Supernova Remnant
Vela Supernova Remnant
The Vela supernova remnant is a supernova remnant in the southern constellation Vela. Its source supernova exploded approximately 11,000-12,300 years ago...
. The gamma rays from the decay of titanium-44 showed that it must have exploded fairly recently (perhaps around 1200 AD), but there is no historical record of it. The flux of gamma rays and x-rays indicates that the supernova was relatively close to us (perhaps 200 parsecs or 600 ly). If so, this is a surprising event because supernovae less than 200 parsecs away are estimated to occur less than once per 100,000 years.
2000 to present
The "SN 2003fg" was discovered in a forming galaxy in 2003. The appearance of this supernova was studied in "real-time", and it has posed several major physical questions as it seems more massive than the Chandrasekhar limitChandrasekhar limit
When a star starts running out of fuel, it usually cools off and collapses into one of three compact forms, depending on its total mass:* a White Dwarf, a big lump of Carbon and Oxygen atoms, almost like one huge molecule...
would allow.
First observed in September 2006, the supernova SN 2006gy
SN 2006gy
SN 2006gy was an extremely energetic supernova, sometimes referred to as a hypernova or quark-nova, that was discovered on September 18, 2006. It was first observed by Robert Quimby and P. Mondol, and then studied by several teams of astronomers using facilities that included the Chandra, Lick, and...
, which occurred in a galaxy called NGC 1260
NGC 1260
NGC 1260 is a spiral galaxy in the constellation Perseus. In 2006, it was home to the second brightest object in the observable universe, supernova SN 2006gy.-External links:*...
(240 million light-years away), is the largest and, until confirmation of luminosity of SN 2005ap
SN 2005ap
SN 2005ap was an extremely energetic type II supernova. It is reported to be the brightest supernova yet recorded, twice as bright as the previous record holder, SN 2006gy...
in October 2007, the most luminous supernova ever observed. The explosion was at least 100 times more luminous than any previously observed supernova, with the progenitor star being estimated 150 times more massive than the Sun. Although this had some characteristics of a Type Ia supernova, Hydrogen was found in the spectrum. It is thought that SN 2006gy is a likely candidate for a pair-instability supernova
Pair-instability supernova
A pair-instability supernova occurs when pair production, the production of free electrons and positrons in the collision between atomic nuclei and energetic gamma rays, reduces thermal pressure inside a supermassive star's core...
. SN 2005ap, which was discovered by Robert Quimby
Robert Quimby
Robert Quimby is an American astronomer who received his Ph.D. in Astronomy from the University of Texas at Austin. As a lead member of the Texas Supernova Survey, Quimby and his team used the relatively small 18-inch ROTSE-IIIb robotic telescope on McDonald Observatory’s Mount Fowlkes, along with...
who also discovered SN 2006gy, was about twice as bright as SN 2006gy and about 300 times as bright as a normal type II supernova.
On May 21, 2008, astronomers announced that they had for the first time caught a supernova on camera just as it was exploding. By chance, a burst of X-rays was noticed while looking at galaxy NGC 2770
NGC 2770
NGC 2770 is a type SASc spiral galaxy located about 88 million light years away, in the constellation Lynx.It has been referred to as the 'Supernova Factory' as three supernovas have occurred there recently: SN 1999eh, SN 2007uy, and SN 2008D...
, 88 million light-years from Earth, and a variety of telescopes were aimed in that direction just in time to capture what has been named SN 2008D
SN 2008D
SN 2008D is a supernova detected with NASA's Swift X-ray telescope. The explosion of the supernova precursor star, in the spiral galaxy NGC 2770 SN 2008D is a supernova detected with NASA's Swift X-ray telescope. The explosion of the supernova precursor star, in the spiral galaxy NGC 2770 SN 2008D...
. "This eventually confirmed that the big X-ray blast marked the birth of a supernova," said Alicia Soderberg of Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
.
One of the many amateur astronomers looking for supernovae, Caroline Moore
Caroline Moore
Caroline Moore is an American amateur astronomer. On November 7, 2008, at the age of 14, Moore discovered supernova 2008ha in the galaxy UGC 12682 in the constellation Pegasus. At that time, Moore was the youngest person to discover a supernova...
, a member of the Puckett Observatory
Puckett Observatory
Puckett Observatory is a private astronomical observatory located in the North Georgia Mountains, near Ellijay, Georgia, United States. It is owned and operated by Tim Puckett. Its primary observation goals are the study of comets and the discovery of supernovae...
Supernova Search Team, found supernova SN 2008ha
SN 2008ha
SN 2008ha was a type Ia supernova which was first observed around November 7, 2008 in the galaxy UGC 12682, which lies in the constellation Pegasus at a distance of about from Earth....
late November 2008. At the age of 14 she has now been declared the youngest person ever to find a supernova. However, in January 2011, 10-year old Kathryn Aurora Gray from Canada was reported to have discovered a supernova, making her the youngest ever to find a supernova. Ms. Gray, her father, and a friend spotted SN 2010lt
SN 2010lt
SN 2010lt is a supernova located in the galaxy UGC 3378 in Camelopardalis. It was discovered by amateur astronomers Kathryn Aurora Gray, her father Paul Gray, of Fredericton, New Brunswick, Canada and David J. Lane of Stillwater Lake, Nova Scotia, Canada. Upon discovery, Kathryn Aurora Gray became...
, a magnitude 17 supernova in galaxy UGC 3378
UGC 3378
UGC 3378 is a galaxy with a star that was observed to go supernova in January of 2011. . The distance to our Solar system is about 248.800.000 light year...
in the constellation Camelopardalis
Camelopardalis
Camelopardalis is a large but faint constellation in the northern sky. The constellation was introduced in 1612 by Petrus Plancius. Some older astronomy books give an alternative spelling of the name, Camelopardus.-Etymology:...
, about 240 million light years away.
In 2009, researchers have found nitrate
Nitrate
The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
s in ice core
Ice core
An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the incremental build up of annual layers of snow, lower layers are older than upper, and an ice...
s from Antarctica at depths corresponding to the known supernovae of 1006 and 1054 AD, as well as from around 1060 AD. The nitrates were apparently formed from nitrogen oxides created by gamma rays from the supernovae. This technique should be able to detect supernovae going back several thousand years.
On November 15, 2010, astronomers using NASA's Chandra X-ray Observatory
Chandra X-ray Observatory
The Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the maximum mass for white dwarfs. "Chandra" also means "moon" or "luminous" in Sanskrit.Chandra...
announced that, while viewing the remnant of SN 1979C
SN 1979C
SN 1979C was a supernova about 50 million light-years away in Messier 100, a spiral galaxy in the constellation Coma Berenices. The Type II supernova was discovered April 19, 1979 by Gus Johnson, a school teacher and amateur astronomer. This type of supernova is known as a core collapse and is the...
in the galaxy Messier 100
Messier 100
Messier 100 is an example of a grand design spiral galaxy located within the southern part of constellation Coma Berenices. It is one of the brightest galaxies in the Virgo cluster, approximately 55 million light-years distant from Earth and has a diameter of 160,000 light years...
, they have discovered an object which could be a young, 30-year-old black hole
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...
. NASA also noted the possibility this object could be a spinning neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...
producing a wind of high energy particles.
On August 24, 2011, the Palomar Transient Factory
Palomar Transient Factory
The Palomar Transient Factory is an astronomical wide-field survey designed to search for optical transient and variable sources. It is fully automated, including a wide-field survey camera, an automated realtime data reduction pipeline, a dedicated photometric follow up telescope, and a full...
automated survey discovered a new Type 1a supernova (SN 2011fe
SN 2011fe
SN 2011fe, initially designated PTF 11kly, is a star which perished in a Type Ia supernova event that is currently visible from Earth. The star was discovered by the Palomar Transient Factory survey on 24 August 2011 during an automated review of images of the Messier 101 from the nights of 22...
) in the Pinwheel Galaxy (M101) shortly after it burst into existence. Being only 21 million lightyears away and detected so early after the event started, it will allow scientists to learn more about the early developments of these types of supernovae.
Future
The estimated rate of supernova production in a galaxy the size of the Milky Way is about one every 50 years. This is much higher than the actual observed rate, implying that a portion of these events have been obscured from the Earth by interstellar dust. The deployment of new instruments that can observe across a wide range of the spectrum, and neutrinoNeutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
detectors, means that the next such event will almost certainly be detected.