Epsilon Aurigae
Encyclopedia
Epsilon Aurigae (ε Aur, ε Aurigae) is a star in the constellation
Auriga
. It is traditionally known as Almaaz, Haldus, or Al Anz. Epsilon Aurigae is an unusual eclipsing binary system comprising an F0
supergiant
and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a binary system of two small B-type stars. About every 27 years, Epsilon Aurigae's brightness drops from an apparent visual magnitude of +2.92 to +3.83. This dimming lasts 640–730 days. In addition to this eclipse, the system also has a low amplitude pulsation with a non-consistent period of around 66 days. The distance to the system is still a subject of debate, but modern estimates place it approximately 2,000 light years from Earth.
Epsilon Aurigae was first suspected to be a variable star when German astronomer Johann Fritsch observed it in 1821. Later observations by Eduard Heis
and Friedrich Wilhelm Argelander
reinforced Fritsch's initial suspicions and attracted attention to the star. Hans Ludendorff
, however, was the first to study it in great detail. His work revealed that the system was an eclipsing binary variable, a star that dims when its partner obscures its light.
Epsilon Aurigae's eclipsing companion has been subject to much debate since the object does not emit as much light as is expected for an object its size. As of 2008, the most popularly accepted model for this companion object is a binary star system surrounded by a massive, opaque disk of dust; theories speculating that the object is a large, semitransparent star or a black hole
have since been discarded.
. Eventually, from 1842 to 1848, German mathematician Eduard Heis
and Prussian astronomer Friedrich Wilhelm Argelander
began observing it once every few years. Both Heis' and Argelander's data revealed that the star had become significantly dimmer by 1847, attracting the full attention of both men at that point. Epsilon Aurigae had brightened significantly, and had returned to "normal" by the following September. As it attracted more attention, more and more data were compiled. The observational data revealed that Epsilon Aurigae did not just vary over a long period, but also experienced short-term variations in brightness as well. Later eclipses took place between 1874 and 1875 and, nearly thirty years later, between 1901 and 1902.
Hans Ludendorff
, who had also been observing Epsilon Aurigae, was the first to conduct a detailed study of the star. In 1904, he published in Astronomische Nachrichten an article titled Untersuchungen über den Lichtwechsel von ε Aurigae (Investigations of the Light Changes of Epsilon Aurigae), where he suggested the star was an Algol variable
and an eclipsing binary.
Epsilon Aurigae has been targeted for observation by International Year of Astronomy
observers from 2009 to 2011, the three years that overlap its next eclipse.
, Donald Hoard of NASA
's Spitzer Science Center at the California Institute of Technology
in Pasadena
reported that observations from NASA's Spitzer Space Telescope
along with earlier observations point to the primary being a post-asymptotic giant branch
star with about 2.2–3.3 times the mass of the Sun periodically eclipsed by just a single B class star inside a disk. This was accomplished by pointing Spitzer at the star using the corner of four of Spitzer's pixels, instead of directly at one, to effectively reduce the telescope's sensitivity and preventing the star from overloading it, then using exposures of one-hundredth of a second, the shortest duration images that can be obtained by Spitzer. The data supports the presence of the companion star's disk, and establish the particle sizes as being like gravel rather than like fine dust.
The pair was formerly believed to be composed of one supergiant F-type star and a massive, though dim, eclipsing component whose exact nature was not known, although a 1985 model proposed it to be a disk of dust. The two entities eclipse each other every 27.1 years, and each eclipse lasts approximately two years. Midway through the eclipse, the system brightens slightly, due to the disk being edge-on, reducing its profile and blocking less of the light from Epsilon Aurigae A. The F-type supergiant and the dust disk are nearly thirty AU apart, which is approximately the distance of the planet Neptune
from the Sun
.
F0. This F-type star has around 135 times the diameter of the Sun, and is 40,000 to 60,000 times as luminous. (Reliable sources vary considerably in their estimates of both quantities.) If the star were in the position of the Sun, it would envelop Mercury and possibly Venus. F-type stars like Epsilon Aurigae tend to glow white and display strong ionized calcium absorption lines and weak hydrogen absorption lines; being a class above the Sun (which is a G-type star), F-type stars are typically hotter than Sunlike stars. Other F-type stars include Procyon
's primary star, the brightest star in the Canis Minor constellation; and Canopus
, the second brightest star in the night sky and the brightest star in the Carina
constellation.
The first hypothesis, set forth in 1937 by astronomers Gerard Kuiper
, Otto Struve
, and Bengt Strömgren
, suggested that Epsilon Aurigae was a binary star system containing an F2 supergiant and an extremely cool "semitransparent" star that would completely eclipse its companion. However, the eclipsing star would scatter light emitted by its eclipsed companion resulting in the observed decrease in magnitude. The scattered light would be detected on Earth as a star visible to the naked eye, although this light would be significantly dimmed. However, astronomer Su-Shu Huang published a paper in 1965 that outlined the defects of the Kuiper-Struve-Strömgren model, and proposed that the companion is a large disk system, edge-on from the perspective of Earth. Robert Wilson
, in 1971, proposed that a "central opening" lay in the disk, a possible reason for the system's sudden brightening mid-way through the eclipse. In 2005, the system was observed in the ultraviolet by the Far Ultraviolet Spectroscopic Explorer
(FUSE); as the star system was not emitting energy at rates characteristic of objects such as the neutron star binary system Circinus X-1
or black hole binary system Cygnus X-1
, the object occupying the center of the disk is not expected to be anything of the sort; in contrast, a new hypothesis has suggested that the central object is actually a B5-type star.
. It is the apex of the isosceles triangle forming the 'nose' of the constellation Auriga. The star is bright enough to be seen from most urban locations with moderate amounts of light pollution
. Visual variable star observers make an estimate of its brightness by comparing its brightness with nearby stars with a known brightness value. Because it is so bright, photometric
observers must use equipment with very large fields of view such as photoelectric photometers or DSLR
cameras. A timetable of eclipse predictions is available and first reports of the eclipse beginning surfaced in August 2009.
has awarded the AAVSO a three-year grant to fund a citizen science
project built around the 2009-2011 eclipse. The project, called Citizen Sky, is organizing and training participants to observe the eclipse and report their data to a central database. In addition, participants will help validate and analyze the data while testing their own theories and publishing original research articles in a peer-reviewed astronomical journal.
(invented by German astronomer Johann Bayer
in his 1603 atlas, Uranometria
). The star is also known colloquially as "Almaaz", "Haldus" or "Al Anz." Both Almaaz and Al Anz derive from the Arabic الماعز al-mācz "(billy) goat", corresponding to the name of the star Capella
, Latin for "nanny goat".
In Chinese
, , meaning Pillars
, refers to an asterism consisting of ε Aurigae, ζ Aurigae
, η Aurigae
, υ Aurigae
, ν Aurigae, τ Aurigae, χ Aurigae
and 26 Aurigae
. Consequently, ε Aurigae itself is known as
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Auriga
Auriga (constellation)
Auriga is a constellation in the northern sky. Its name is Latin for 'charioteer' and its stars form a shape that has been associated with the pointed helmet of a charioteer. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains among the 88 modern...
. It is traditionally known as Almaaz, Haldus, or Al Anz. Epsilon Aurigae is an unusual eclipsing binary system comprising an F0
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
supergiant
Supergiant
Supergiants are among the most massive stars. They occupy the top region of the Hertzsprung-Russell diagram. In the Yerkes spectral classification, supergiants are class Ia or Ib . They typically have bolometric absolute magnitudes between -5 and -12...
and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a binary system of two small B-type stars. About every 27 years, Epsilon Aurigae's brightness drops from an apparent visual magnitude of +2.92 to +3.83. This dimming lasts 640–730 days. In addition to this eclipse, the system also has a low amplitude pulsation with a non-consistent period of around 66 days. The distance to the system is still a subject of debate, but modern estimates place it approximately 2,000 light years from Earth.
Epsilon Aurigae was first suspected to be a variable star when German astronomer Johann Fritsch observed it in 1821. Later observations by Eduard Heis
Eduard Heis
Eduard Heis was a German mathematician and astronomer.He completed his education at the University of Bonn in 1827, then taught mathematics at a school in Cologne. In 1832 he taught at Aachen, and remained there until 1852. He was then appointed by King Frederick William IV to a chair position at...
and Friedrich Wilhelm Argelander
Friedrich Wilhelm Argelander
Friedrich Wilhelm August Argelander was a German astronomer. He is known for his determinations of stellar brightnesses, positions, and distances.- Life and work :...
reinforced Fritsch's initial suspicions and attracted attention to the star. Hans Ludendorff
Hans Ludendorff
Friedrich Wilhelm Hans Ludendorff was a German astronomer and astrophysicist. He was the younger brother of General Erich Ludendorff....
, however, was the first to study it in great detail. His work revealed that the system was an eclipsing binary variable, a star that dims when its partner obscures its light.
Epsilon Aurigae's eclipsing companion has been subject to much debate since the object does not emit as much light as is expected for an object its size. As of 2008, the most popularly accepted model for this companion object is a binary star system surrounded by a massive, opaque disk of dust; theories speculating that the object is a large, semitransparent star or a 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...
have since been discarded.
Observational history
Although the star is easily visible to the naked eye, Johann Fritsch's 1821 observations suggest he was the first to notice that the system was a variableVariable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
. Eventually, from 1842 to 1848, German mathematician Eduard Heis
Eduard Heis
Eduard Heis was a German mathematician and astronomer.He completed his education at the University of Bonn in 1827, then taught mathematics at a school in Cologne. In 1832 he taught at Aachen, and remained there until 1852. He was then appointed by King Frederick William IV to a chair position at...
and Prussian astronomer Friedrich Wilhelm Argelander
Friedrich Wilhelm Argelander
Friedrich Wilhelm August Argelander was a German astronomer. He is known for his determinations of stellar brightnesses, positions, and distances.- Life and work :...
began observing it once every few years. Both Heis' and Argelander's data revealed that the star had become significantly dimmer by 1847, attracting the full attention of both men at that point. Epsilon Aurigae had brightened significantly, and had returned to "normal" by the following September. As it attracted more attention, more and more data were compiled. The observational data revealed that Epsilon Aurigae did not just vary over a long period, but also experienced short-term variations in brightness as well. Later eclipses took place between 1874 and 1875 and, nearly thirty years later, between 1901 and 1902.
Hans Ludendorff
Hans Ludendorff
Friedrich Wilhelm Hans Ludendorff was a German astronomer and astrophysicist. He was the younger brother of General Erich Ludendorff....
, who had also been observing Epsilon Aurigae, was the first to conduct a detailed study of the star. In 1904, he published in Astronomische Nachrichten an article titled Untersuchungen über den Lichtwechsel von ε Aurigae (Investigations of the Light Changes of Epsilon Aurigae), where he suggested the star was an Algol variable
Algol variable
Algol variables or Algol-type binaries are a class of eclipsing binary stars where the orbital plane of the stars are coincident with the line of sight from Earth. When the cooler component passes in front of the hotter one, part of the latter's light is blocked, and the total brightness of the...
and an eclipsing binary.
Epsilon Aurigae has been targeted for observation by International Year of Astronomy
International Year of Astronomy
The International Year of Astronomy was a year-long celebration of astronomy that took place in 2009 to coincide with the 400th anniversary of the first recorded astronomical observations with a telescope by Galileo Galilei and the publication of Johannes Kepler's Astronomia nova in the 17th century...
observers from 2009 to 2011, the three years that overlap its next eclipse.
Spitzer observations, 2009
At the January 2010 meeting of the American Astronomical SocietyAmerican Astronomical Society
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...
, Donald Hoard of NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's Spitzer Science Center at the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...
in Pasadena
Pasadena, California
Pasadena is a city in Los Angeles County, California, United States. Although famous for hosting the annual Rose Bowl football game and Tournament of Roses Parade, Pasadena is the home to many scientific and cultural institutions, including the California Institute of Technology , the Jet...
reported that observations from NASA's Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
along with earlier observations point to the primary being a post-asymptotic giant branch
Asymptotic Giant Branch
The asymptotic giant branch is the region of the Hertzsprung-Russell diagram populated by evolving low to medium-mass stars. This is a period of stellar evolution undertaken by all low to intermediate mass stars late in their lives....
star with about 2.2–3.3 times the mass of the Sun periodically eclipsed by just a single B class star inside a disk. This was accomplished by pointing Spitzer at the star using the corner of four of Spitzer's pixels, instead of directly at one, to effectively reduce the telescope's sensitivity and preventing the star from overloading it, then using exposures of one-hundredth of a second, the shortest duration images that can be obtained by Spitzer. The data supports the presence of the companion star's disk, and establish the particle sizes as being like gravel rather than like fine dust.
System components and variability
The Epsilon Aurigae system is now under intense observation and investigation due to the Spitzer and Citizen Sky programs. Therefore, its composition is currently in question.The pair was formerly believed to be composed of one supergiant F-type star and a massive, though dim, eclipsing component whose exact nature was not known, although a 1985 model proposed it to be a disk of dust. The two entities eclipse each other every 27.1 years, and each eclipse lasts approximately two years. Midway through the eclipse, the system brightens slightly, due to the disk being edge-on, reducing its profile and blocking less of the light from Epsilon Aurigae A. The F-type supergiant and the dust disk are nearly thirty AU apart, which is approximately the distance of the planet Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
.
Visible component
The visible component, Epsilon Aurigae A, is a semiregular pulsating post-asymptotic giant branch star belonging to the spectral classStellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
F0. This F-type star has around 135 times the diameter of the Sun, and is 40,000 to 60,000 times as luminous. (Reliable sources vary considerably in their estimates of both quantities.) If the star were in the position of the Sun, it would envelop Mercury and possibly Venus. F-type stars like Epsilon Aurigae tend to glow white and display strong ionized calcium absorption lines and weak hydrogen absorption lines; being a class above the Sun (which is a G-type star), F-type stars are typically hotter than Sunlike stars. Other F-type stars include Procyon
Procyon
Procyon is the brightest star in the constellation Canis Minor. To the naked eye, it appears to be a single star, the seventh brightest in the night sky with a visual apparent magnitude of 0.34...
's primary star, the brightest star in the Canis Minor constellation; and Canopus
Canopus
Canopus |Alpha]] Carinae) is the brightest star in the southern constellation of Carina and Argo Navis, and the second brightest star in the night-time sky, after Sirius. Canopus's visual magnitude is −0.72, and it has an absolute magnitude of −5.53.Canopus is a supergiant of spectral...
, the second brightest star in the night sky and the brightest star in the 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:...
constellation.
Eclipsing component
The eclipsing component emits a negligible amount of light, and is not visible to the naked eye. A heated region, however, has been discovered in the center of the object. The exact form of Epsilon Aurigae's eclipsing component is not known. Hypotheses concerning the nature of this second object have been proposed, three of which have garnered attention from the scientific community.The first hypothesis, set forth in 1937 by astronomers Gerard Kuiper
Gerard Kuiper
Gerard Peter Kuiper , Netherlands – December 24, 1973, Mexico City) was a Dutch-American astronomer after whom the Kuiper belt was named.-Early life:...
, Otto Struve
Otto Struve
Otto Struve was a Russian astronomer. In Russian, his name is sometimes given as Otto Lyudvigovich Struve ; however, he spent most of his life and his entire scientific career in the United States...
, and Bengt Strömgren
Bengt Strömgren
Bengt Georg Daniel Strömgren was a Danish astronomer and astrophysicist.Bengt Strömgren was born in Gothenburg. His parents were Hedvig Strömgren and Svante Elis Strömgren, who was professor of astronomy at the University of Copenhagen and director of the University Observatory in Copenhagen...
, suggested that Epsilon Aurigae was a binary star system containing an F2 supergiant and an extremely cool "semitransparent" star that would completely eclipse its companion. However, the eclipsing star would scatter light emitted by its eclipsed companion resulting in the observed decrease in magnitude. The scattered light would be detected on Earth as a star visible to the naked eye, although this light would be significantly dimmed. However, astronomer Su-Shu Huang published a paper in 1965 that outlined the defects of the Kuiper-Struve-Strömgren model, and proposed that the companion is a large disk system, edge-on from the perspective of Earth. Robert Wilson
Robert Wilson (astronomer)
Sir Robert Wilson FRS, CBE, Kt, was the son of a Durham miner. He studied physics at King's College, Durham and obtained his PhD in Edinburgh, where he worked at the Royal Observatory on stellar spectra...
, in 1971, proposed that a "central opening" lay in the disk, a possible reason for the system's sudden brightening mid-way through the eclipse. In 2005, the system was observed in the ultraviolet by the Far Ultraviolet Spectroscopic Explorer
Far Ultraviolet Spectroscopic Explorer
The Far Ultraviolet Spectroscopic Explorer is a space-based telescope operated by the Johns Hopkins University Applied Physics Laboratory. FUSE was launched on a Delta II rocket on June 24, 1999, as a part of NASA's Origins program...
(FUSE); as the star system was not emitting energy at rates characteristic of objects such as the neutron star binary system Circinus X-1
Circinus X-1
Circinus X-1 is an X-ray binary star system that includes a neutron star. Observation of Circinus X-1 in July 2007 revealed the presence of X-ray jets normally found in black hole systems; it is the first of the sort to be discovered that displays this similarity to black holes.-Location:On June...
or black hole binary system Cygnus X-1
Cygnus X-1
Cygnus X-1 is a well-known galactic X-ray source in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 2.3 Wm−2Hz−1...
, the object occupying the center of the disk is not expected to be anything of the sort; in contrast, a new hypothesis has suggested that the central object is actually a B5-type star.
Observation
The star is easily found because of its brightness and apparent proximity to the star CapellaCapella (star)
Capella is the brightest star in the constellation Auriga, the sixth brightest star in the night sky and the third brightest star in the northern celestial hemisphere, after Arcturus and Vega. Although it appears to be a single star to the naked eye, it is actually a star system of four stars in...
. It is the apex of the isosceles triangle forming the 'nose' of the constellation Auriga. The star is bright enough to be seen from most urban locations with moderate amounts of light pollution
Light pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...
. Visual variable star observers make an estimate of its brightness by comparing its brightness with nearby stars with a known brightness value. Because it is so bright, photometric
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
observers must use equipment with very large fields of view such as photoelectric photometers or DSLR
Digital single-lens reflex camera
Most digital single-lens reflex cameras are digital cameras that use a mechanical mirror system and pentaprism to direct light from the lens to an optical viewfinder on the back of the camera....
cameras. A timetable of eclipse predictions is available and first reports of the eclipse beginning surfaced in August 2009.
Citizen Sky
The National Science FoundationNational Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
has awarded the AAVSO a three-year grant to fund a citizen science
Citizen science
Citizen science is a term used for the systematic collection and analysis of data; development of technology; testing of natural phenomena; and the dissemination of these activities by researchers on a primarily avocational basis...
project built around the 2009-2011 eclipse. The project, called Citizen Sky, is organizing and training participants to observe the eclipse and report their data to a central database. In addition, participants will help validate and analyze the data while testing their own theories and publishing original research articles in a peer-reviewed astronomical journal.
Etymology
"Epsilon Aurigae" is the system's Bayer designationBayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...
(invented by German astronomer Johann Bayer
Johann Bayer
Johann Bayer was a German lawyer and uranographer . He was born in Rain, Bavaria, in 1572. He began his study of philosophy in Ingolstadt in 1592, and moved later to Augsburg to begin work as a lawyer. He grew interested in astronomy during his time in Augsburg...
in his 1603 atlas, Uranometria
Uranometria
Uranometria is the short title of a star atlas produced by Johann Bayer.It was published in Augsburg, Germany, in 1603 by Christophorus Mangus under the full title Uranometria : omnium asterismorum continens schemata, nova methodo delineata, aereis laminis expressa. This translates to...
). The star is also known colloquially as "Almaaz", "Haldus" or "Al Anz." Both Almaaz and Al Anz derive from the Arabic الماعز al-mācz "(billy) goat", corresponding to the name of the star Capella
Capella (star)
Capella is the brightest star in the constellation Auriga, the sixth brightest star in the night sky and the third brightest star in the northern celestial hemisphere, after Arcturus and Vega. Although it appears to be a single star to the naked eye, it is actually a star system of four stars in...
, Latin for "nanny goat".
In Chinese
Chinese language
The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...
, , meaning Pillars
Net (Chinese constellation)
The Net mansion is one of the Twenty-eight mansions of the Chinese constellations. It is one of the western mansions of the White Tiger.-Asterisms:...
, refers to an asterism consisting of ε Aurigae, ζ Aurigae
Zeta Aurigae
Zeta Aurigae is a star in the constellation Auriga. It has the traditional names Haedus and Sadatoni . It is one of the two hædi of the she-goat Capella, the other being Hoedus II, Eta Aurigae...
, η Aurigae
Eta Aurigae
Eta Aurigae is a star in the constellation Auriga. Along with ζ Aurigae it represents one of the Kids of the she-goat Capella, from which it gets its Latin traditional name Hoedus II or Haedus II, from the Latin hædus "kid"; Zeta Aurigae is Hoedus I...
, υ Aurigae
Upsilon Aurigae
Upsilon Aurigae is a star in the constellation Auriga.Upsilon Aurigae is a M-type red giant with an apparent magnitude of +4.72. It is approximately 475 light-years from Earth.-References:* *...
, ν Aurigae, τ Aurigae, χ Aurigae
Chi Aurigae
Chi Aurigae is a binary star in the constellation Auriga. It is at least 2000 light-years from Earth.Chi Aurigae is a spectroscopic binary which is classified as a blue-white B-type supergiant with an apparent magnitude of +4.71. The binary has an orbital period of 655.16 days.-References:* *...
and 26 Aurigae
26 Aurigae
26 Aurigae is a star in the constellation Auriga. Its apparent magnitude is 5.40.-References:* * * -Components:...
. Consequently, ε Aurigae itself is known as
External links
- YouTube video describing the system using Lite Brite diagrams
- David Darling's encyclopedia
- Epsilon Aurigae article by Dr. Jim Kaler.
- The coming eclipse of epsilon Aurigae by Dr. Robert Stencel, a.k.a "Dr. Bob"
- Epsilon Aurigae Web site by Hopkins Phoenix Observatory (HPO)
- How to Locate Capella and the Auriga constellation
- Astronomy Picture of the DayAstronomy Picture of the DayAstronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
2010 January 8 The Mystery of the Fading Star - AAVSO Variable Star of the Month. January 2008: Epsilon Aurigae
- BBC News 'First image' of star's eclipse captured by scientists .7 April 2010. University of St Andrews study. Accessed 7 April 2010.
- Nat. Geo., First Pictures: Mystery Disk Eclipses Star. April 7, 2010