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V838 Monocerotis (V838 Mon) is an enigmatic variable star in the constellation Monoceros about 20,000 light years (6 kpc)[1] from the Sun. The star experienced a major outburst in early 2002. Originally believed to be a typical nova eruption, it was quickly realized to be something completely different. The reason for the outburst is still uncertain, but several theories have been put forward, including an eruption related to stellar death processes and a merger of a binary star or planets. Image File history File linksMetadata Download high resolution version (1651x1651, 276 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): V838 Monocerotis Metadata This file contains additional information, probably added from the digital camera or scanner used to...
Reflected light following path B arrives shortly after the direct flash following path A but before light following path C. B and C have the same apparent distance from the star as seen from Earth. ...
The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ...
The National Aeronautics and Space Administration (NASA) is an agency of the United States Government, responsible for the nations public space program. ...
This article is about the European Space Agency. ...
From the Glossary of Astronomical Terms by the Harvard-Smithsonian Center for Astrophysics: Either of the two points (vernal, autumnal) on the celestial sphere where the ecliptic (which is the apparent path of the sun on the sky) intersects the celestial equator. ...
This article or section does not adequately cite its references or sources. ...
Equatorial Coordinates Right ascension (abbrev. ...
In astronomy, declination (abbrev. ...
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In astronomy, many stars are referred to simply by catalogue numbers. ...
SIMBAD (the Set of Identifications, Measurements, and Bibliography for Astronomical Data) is a database of astronomical information about objects within the Milky Way. ...
Most stars are of almost constant luminosity. ...
STAR is an acronym for: Organizations Society for Telescopy, Astronomy, and Radio, a non-profit New Jersey astronomy club. ...
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Monoceros (IPA: , Greek: ) is a faint constellation on the winter night sky, surrounded by Orion to the east, Gemini to the north, Canis Major to the south and Hydra to the west. ...
A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in vacuum in one Julian year. ...
Stellar parallax motion The parsec (symbol pc) is a unit of length used in astronomy. ...
The Sun is the star at the center of the Solar System. ...
For album titles with the same name, see 2002 (album). ...
Artists conception of a white dwarf star accreting hydrogen from a larger companion A nova (pl. ...
Outburst
On January 10, 2002, a previously unknown star was seen to brighten up in Monoceros, the Unicorn.[2] Being a new variable star, it was designated V838 Monocerotis, the 838th variable star of Monoceros. The initial light curve resembled that of a nova, an eruption that occurs when enough hydrogen gas has accumulated on the surface of a white dwarf from its close binary companion. Therefore it was also designated Nova Monocerotis 2002. V838 Monocerotis reached maximum visual magnitude of 6.75 on February 6, 2002 after which it started to dim rapidly, as expected. However, in early March the star started to brighten again, this time mostly in infrared wavelengths. Yet another brightening in infrared occurred in early April after which the star returned to near its original brightness before the eruption, magnitude 15.6. The lightcurve produced by the eruption is unlike anything previously seen.[3] The Unicorn (from Latin unus one and cornu horn) is a legendary creature whose power is exceeded only by its mystery. ...
In astronomy, a light curve is a graph of light intensity as a function of time. ...
Artists conception of a white dwarf star accreting hydrogen from a larger companion A nova (pl. ...
General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...
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Artists impression of a binary system consisting of a black hole, with an accretion disc around it, and a main sequence star. ...
The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ...
Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ...
The star brightened to about a million times solar luminosity[4] ensuring that at the time of maximum V838 Monocerotis was one of the most luminous stars in the Milky Way galaxy. The brightening was caused by a rapid expansion of the outer layers of the star. The star was observed using the Palomar Testbed Interferometer which provided a radius of 1,570 ± 400 times solar (comparable to Jupiter's orbital radius), confirming the earlier indirect calculations.[5] The expansion took only a couple of months meaning the expansion speed was phenomenal. The laws of thermodynamics dictate that expanding gas cools. Therefore the star became extremely cool and deep red. In fact, some astronomers argue that the spectra of the star resembled that of L-type brown dwarfs. If that is the case, V838 Monocerotis would be the first known L-type supergiant.[6] Luminosity has different meanings in several different fields of science. ...
It has been suggested that Andromeda-Milky Way collision be merged into this article or section. ...
The Palomar Testbed Interferometer is a near-IR, long-baseline stellar interferometer located at Palomar Observatory in north San Diego County. ...
The Sun is the star at the center of the Solar System. ...
Adjectives: Jovian Atmosphere Surface pressure: 20–200 kPa[4] (cloud layer) Composition: ~86% H2 ~13% Helium 0. ...
Thermodynamics (from the Greek thermos meaning heat and dynamics meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ...
An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ...
In most modern usages of the word spectrum, there is a unifying theme of between extremes at either end. ...
This brown dwarf (smaller object) orbits the star Gliese 229, which is located in the constellation Lepus about 19 light years from Earth. ...
In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ...
Supergiants are the most massive stars. ...
Other possibly similar events There are a handful of outbursts that resemble the one which occurred on V838 Monocerotis. In 1988 a red star was detected erupting in the Andromeda Galaxy. The star, designated M31-RV, reached the absolute bolometric magnitude of −9.95 at maximum (corresponding a luminosity of 7.5 million times solar) before dimming beyond detectability. A similar eruption occurred in 1994 in the Milky Way (V4332 Sagittarii).[7] M31 in a small telescope The Andromeda Galaxy (IPA: , also known as Messier 31, M31, or NGC 224; older texts often called it the Andromeda Nebula) is a spiral galaxy approximately 2. ...
In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ...
Progenitor star Some details are emerging on the nature of the star that experienced the outburst. Based on the light echo the eruption generated, the distance of the star was first measured to be 1,900 to 2,900 light years. Combined with the apparent magnitude measured from pre-eruption photographs, it was thought to be an underluminous F-type dwarf not much unlike our Sun which posed a considerable enigma.[8] Reflected light following path B arrives shortly after the direct flash following path A but before light following path C. B and C have the same apparent distance from the star as seen from Earth. ...
In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ...
More accurate measurements gave a much larger distance, 20,000 light years (6 kpc). It appears that the star is considerably more massive and luminous than the Sun. The mass of the star is probably from 5 to 10 times solar,[9] and luminosity from 550 to 5,000 times solar. The original radius may have been about 5 times solar and temperature 4,700–30,000 K.[1] Needless to say, these values are very approximate. Munari et al. (2005) suggest that the progenitor star is in fact a very massive supergiant with a mass of about 65 times solar. They also conclude that the system may be only about 4 million years old.[10] The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ...
The spectrum of V838 Monocerotis reveals a companion, a hot blue B-type main sequence star probably not much different from the erupted star.[9] It is also possible that the erupted star was slightly less massive than the companion and only just entering the main sequence.[8] In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ...
Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ...
Based on the photometric parallax of the companion, Munari et al. get a greater distance, 36,000 light years (10 kpc).[10] This does not adequately cite its references or sources. ...
Light echo
 Images showing the expansion of the light echo. Credit: NASA/ ESA. Rapidly brightening objects like novae and supernovae are known to produce a phenomenon known as light echo. The light that travels directly from the object arrives first. If there are clouds of interstellar matter between the star and the observer, some light is reflected from the clouds. Because of the longer path, the reflected light arrives later producing a vision of expanding rings of light around the erupted object. In addition, the rings appear to travel faster than the speed of light.[3] Image File history File links Size of this preview: 800 × 400 pixel Image in higher resolution (1000 × 500 pixel, file size: 75 KB, MIME type: image/jpeg) From http://hubblesite. ...
Image File history File links Size of this preview: 800 × 400 pixel Image in higher resolution (1000 × 500 pixel, file size: 75 KB, MIME type: image/jpeg) From http://hubblesite. ...
The National Aeronautics and Space Administration (NASA) is an agency of the United States Government, responsible for the nations public space program. ...
This article is about the European Space Agency. ...
Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ...
Reflected light following path B arrives shortly after the direct flash following path A but before light following path C. B and C have the same apparent distance from the star as seen from Earth. ...
The interstellar medium (or ISM) is the name astronomers give to the tenuous gas and dust that pervade interstellar space. ...
A line showing the speed of light on a scale model of Earth and the Moon The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness. It is the speed of all electromagnetic radiation...
In the case of V838 Monocerotis, the light echo produced was unprecedented and is well documented in images taken by the Hubble Space Telescope. It is not yet clear if the surrounding nebulosity is associated with the star itself. If that is the case, they may have been produced by the star in earlier eruptions which would rule out several models that are based on single catastrophic events.[3] However, there is strong evidence that the V838 Monocerotis system is very young and still embedded in the nebula from which it formed.[4] The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ...
The Triangulum Emission Nebula NGC 604 lies in a spiral arm of Galaxy M33, 2. ...
Interestingly, the first eruption occurred at shorter wavelengths (i.e. was bluer) and can be seen in the light echo: the outer border of the echo is bluish in the Hubble images.[3]
Models So far several rather different explanations for the eruption of V838 Monocerotis have been published.
Atypical nova outburst The outburst of V838 Monocerotis may be a nova eruption after all, albeit a very unusual one. However, this is very unlikely considering that the system includes a B-type star, and stars of this type are young and massive. There has not been enough time for a possible white dwarf to cool and accrete enough material to cause the eruption.[7]
Thermal pulse of a dying star V838 Monocerotis may be a post-asymptotic giant branch star, on the verge of its death. The nebulosity illuminated by the light echo may actually be shells of dust surrounding the star, created by the star during previous similar outbursts. The brightening may have been a so-called helium flash, where the core of a dying low-mass star suddenly ignites carbon fusion disrupting, but not destroying, the star. Such an event is known to have occurred in Sakurai's object. However, several pieces of evidence supports the argument that the dust is interstellar rather than centered around V838 Monoceros. A dying star that has lost its outer envelopes would be appropriately hot, but the evidence points to a young star instead.[9] A period of Stellar evolution undertaken by all low to intermediate mass stars (0. ...
A Helium flash is the sudden beginning of helium burning in the core of intermediate mass stars, or on the surface of an accreting white dwarf star. ...
General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ...
The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...
Thermonuclear event within a massive supergiant According to some evidence, V838 Monocerotis may be a very massive supergiant. If that is the case, the outburst may have been a so-called carbon flash, a thermonuclear event where a shell in the star containing helium suddenly ignites and starts to fuse carbon. Very massive stars survive multiple such events, however they experience heavy mass loss (about half of the original mass is lost while in the main sequence) before settling as extremely hot Wolf-Rayet stars. This theory may also explain the apparent dust shells around the star. V838 Monoceros is located in the approximate direction of the antigalactic centre and off from the disk of the Milky Way. Stellar birth is less active in outer galactic regions, and it is not clear how such a massive star can form there. However, there are very young clusters like Ruprecht 44 and the 4 million years old NGC 1893 at a distance of ca. 7 kpc and 6 kpc, respectively.[10] Supergiants are the most massive stars. ...
At the end of the 20th century, Thermonuclear has came to imply anything which has to do with fusion nuclear reactions which are triggered by particles of thermal energy. ...
General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Standard atomic weight 4. ...
Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ...
Artists impression of a Wolf-Rayet star Wolf-Rayet stars (often referred to as WR stars) are evolved, hot, massive stars which have very strong stellar winds. ...
Star formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. ...
This article is about the unit of length. ...
This article is about the unit of length. ...
Mergeburst The outburst may have been the result of a so-called mergeburst, the merger of two main sequence stars (or an 8 M☉ main sequence star and a 0.3 M☉ pre-main sequence star). This model is strengthened by the apparent youth of the system and the fact that multiple stellar systems may be unstable. The less massive component may have been in a very eccentric orbit or deflected towards the massive one. Computer simulations have shown the merger model to be plausible. The simulations also show that the inflated envelope would have come almost entirely from the smaller component. In addition, the merger model explains the multiple peaks in the light curve observed during the outburst.[4] A computer simulation or a computer model is a computer program that attempts to simulate an abstract model of a particular system. ...
Planetary capture event Perhaps the most intriguing possibility is that V838 Monocerotis may have swallowed its giant planets. If one of the planets entered into the atmosphere of the star, the stellar atmosphere would have begun slowing down the planet. As the planet penetrated deeper into the atmosphere, friction would become stronger and kinetic energy would be released into the star more rapidly. The star's envelope would then warm up enough to trigger deuterium fusion, which would lead to rapid expansion. The later peaks may then have occurred when two other planets entered into the expanded envelope. The authors of this model calculate that every year about 0.4 planetary capture events occur in Sun-like stars, whereas for massive stars like V838 Monocerotis the rate is ~0.5–2.5 events per year.[1] The eight planets and three dwarf planets of the Solar System. ...
Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of planet Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ...
See also In astronomy, stellar evolution is the sequence of radical changes that a star undergoes during its lifetime (the time in which it emits light and heat). ...
References - ^ a b c Retter, A.; Zhang, B.; Siess, L.; Levinson, A. (May 22, 2006). "The planets capture model of V838 Monocerotis: conclusions for the penetration depth of the planet/s". 1. Retrieved on 2006-08-10.
- ^ Brown, N. J. (January 10, 2002). IAU Circular No. 7785. Retrieved on 2006 August 10.
- ^ a b c d Bond, Howard E.; Henden, Arne; Levay, Zoltan G.; Panagia, Nino; Sparks, William B.; Starrfield, Sumner; Wagner, R. Mark; Corradi, R. L. M.; Munari, U. (March 27, 2003). "An energetic stellar outburst accompanied by circumstellar light echoes". Nature 422 (6930): 405–408. DOI:10.1038/nature01508. Retrieved on 2006-08-10.
- ^ a b c Soker, N.; Tylenda, R. (June 15, 2006). "Modelling V838 Monocerotis as a Mergeburst Object". 1.
- ^ Lane, B. F.; Retter, A.; Thompson, R. R.; Eisner, J. A. (April, 2005). "Interferometric Observations of V838 Monocerotis". The Astrophysical Journal 622 (2): L137–L140. DOI:10.1086/429619. Retrieved on 2006-08-10.
- ^ Evans, A.; Geballe, T. R.; Rushton, M. T.; Smalley, B.; van Loon, J. Th.; Eyres, S. P. S.; Tyne, V. H. (August, 2003). "V838 Mon: an L supergiant?". Monthly Notice of the Royal Astronomical Society 343 (3): 1054. DOI:10.1046/j.1365-8711.2003.06755.x. Retrieved on 2006-08-10.
- ^ a b Boschi, F.; Munari, U. (May, 2004). "M 31-RV evolution and its alleged multi-outburst pattern". Astronomy & Astrophysics 418: 869–875. DOI:10.1051/0004-6361:20035716. Retrieved on 2006-08-10. M31-RV - 0402313
- ^ a b Tylenda, R. (June 4, 2005). "Evolution of V838 Monocerotis during and after the 2002 eruption". Astronomy and Astrophysics 436 (3): 1009–1020. DOI:10.1051/0004-6361:20052800. Retrieved on 2006-08-10.
- ^ a b c Tylenda, R.; Soker, N.; Szczerba, R. (October, 2005). "On the progenitor of V838 Monocerotis". Astronomy and Astrophysics 441 (3): 1099-1109. DOI:10.1051/0004-6361:20042485. Retrieved on 2006-08-10.
- ^ a b c Munari, U.; Munari, U.; Henden, A.; Vallenari, A.; Bond, H. E.; Corradi, R. L. M.; Crause, L.; Desidera, S.; Giro, E.; Marrese, P. M.; Ragaini, S.; Siviero, A.; Sordo, R.; Starrfield, S.; Tomov, T.; Villanova, S.; Zwitter, T.; Wagner, R. M. (May 2, 2005). "On the distance, reddening and progenitor of V838 Mon". Astronomy and Astrophysics 434 (3): 1107–1116. DOI:10.1051/0004-6361:20041751. Retrieved on 2006-08-10.
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...
For the Manfred Mann album, see 2006 (album). ...
August 10 is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ...
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