SCP 06F6 is (or was) an

astronomical object An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ''object'' and ''body'' are often us ...

of unknown type, discovered on 21 February 2006 in the constellation

Boötes Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from la, Boōtēs, which comes from grc-gre, Βοώτης, Boṓtē ...

Space 'firefly' resembles no known object
''New Scientist News'', 16 September 2008 during a survey of

galaxy cluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-la ...

CL 1432.5+3332.8 with the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most ver ...

Advanced Camera for Surveys The Advanced Camera for Surveys (ACS) is a third-generation axial instrument aboard the Hubble Space Telescope (HST). The initial design and scientific capabilities of ACS were defined by a team based at Johns Hopkins University. ACS was assembl ...

Wide Field Channel.Barbary et al.
Discovery of an Unusual Optical Transient with the Hubble Space Telescope
accepted September 8, 2008, for later publication in the

Astrophysical Journal ''The Astrophysical Journal'', often abbreviated ''ApJ'' (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and Jam ...

According to research authored by Kyle Barbary of the

Supernova Cosmology Project The Supernova Cosmology Project is one of two research teams that determined the likelihood of an accelerating universe and therefore a positive cosmological constant, using data from the redshift of Type Ia supernovae. The project is headed by S ...

, the object brightened over a period of roughly 100 days, reaching a peak intensity of

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

21; it then faded over a similar period. Barbary and colleagues report that the

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of color ...

of light emitted from the object does not match known supernova types, and is dissimilar to any known

phenomenon A phenomenon (plural, : phenomena) is an observable event. The term came into its modern Philosophy, philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influe ...

in the Sloan Digital Sky Survey database. The light in the blue region shows broad line features, while the red region shows continuous emission.Mystery object spied with Hubble
The European Homepage for the NASA/ESA Hubble Space Telescope November 2008 update The spectrum shows a handful of spectral lines, but when astronomers try to trace any one of them to an element the other lines fail to match up with any other known elements. Because of its uncommon spectrum, the team was not able to determine the distance to the object using standard

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in f ...

techniques; it is not even known whether the object is within or outside the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked ey ...

. Furthermore, no Milky Way star or external galaxy has been detected at this location, meaning any source is very faint. The European X-ray satellite '' XMM Newton'' made an observation in early August 2006 which appears to show an X-ray glow around SCP 06F6,How they wonder what you are
''Nature News'', 19 September 2008 two orders of magnitude more luminous than that of supernovae.Gänsicke et al.
SCP06F6: A carbon-rich extragalactic transient at redshift z~0.14
Preprint, 2008. Observations from the

Palomar Transient Factory The Palomar Transient Factory (PTF, obs. code: I41), was an astronomical survey using a wide-field survey camera designed to search for optical transient and variable sources such as variable stars, supernovae, asteroids and comets. The projec ...

, reported in 2009, indicate a redshift ''z'' = 1.189 and a peak magnitude of −23.5 absolute (comparable to SN2005ap), making SCP 06F6 one of the most luminous transient phenomena known as of that date.

Possible causes

Supernovae reach their maximum brightness in only 20 days, and then take much longer to fade away. Researchers had initially conjectured that SCP 06F6 might be an extremely remote supernova; relativistic time dilation might have caused a 20-day event to stretch out over a period of 100 days. But this explanation now seems unlikely. Other conjectures that have been advanced involve a collision between a

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...

and an

asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic o ...

, or the collision of a white dwarf with a

black hole A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...

. An analysis by a team from the

University of Warwick , mottoeng = Mind moves matter , established = , type = Public research university , endowment = £7.0 million (2021) , budget = £698.2 million (202 ...

(Boris Gänsicke et al.) suggests that the light spectrum is "consistent with emission from a cool,

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

-rich atmosphere at a

of z~0.14", possibly representing the core collapse and explosion of a

carbon star A carbon star (C-type star) is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monoxide, which consumes mo ...

. Gänsicke's group concurs with Barbary and colleagues that SCP 06F6 may represent "a new class" of

celestial object An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ''object'' and ''body'' are often us ...

. The analysis of Israeli astronomers of Technion suggests four alternative explanations for SCP 06F6, in plausibility order: the tidal destruction of a carbon-oxygen

by an

intermediate-mass black hole An intermediate-mass black hole (IMBH) is a class of black hole with mass in the range 102–105 solar masses: significantly more than stellar black holes but less than the 105–109 solar mass supermassive black holes. Several IMBH candidate obje ...

, a

type Ia A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white ...

supernova exploding inside the dense stellar wind of a

, an

that was swallowed up by a white dwarf or, least likely, a

core-collapse supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

. Observations in 2009 indicate that it may be a

pair-instability supernova A pair-instability supernova is a type of supernova predicted to occur when pair production, the production of free electrons and positrons in the collision between atomic nuclei and energetic gamma rays, temporarily reduces the internal radiati ...

. The event was similar to

SN 2005ap SN 2005ap was an extremely energetic type Ic supernova in the galaxy SDSS J130115.12+274327.5. With a peak absolute magnitude of around −22.7, it is the second-brightest superluminous supernova yet recorded, twice as bright as the previo ...

, and other unusually bright supernova suggesting that it was a new type of supernova.

References

External links

Light curves and spectra
on th
Open Supernova Catalog

CBET 546

* ttps://www.newscientist.com/article/dn14738-space-firefly-resembles-no-known-object.html New Scientist's article from September 2008
New Sci June 2009

Astrophysical Journal: Boris T. Gänsicke et al, ''SCP 06F6: A CARBON-RICH EXTRAGALACTIC TRANSIENT AT REDSHIFT z ~ 0.14''. May, 2009
{{Boötes, state=collapsed Supernovae Discoveries by the Hubble Space Telescope 20060221 Boötes Unsolved problems in astronomy