Messier 63 or M63, also known as NGC 5055 or the seldom-used Sunflower Galaxy, is a spiral galaxy in the northern constellation of

Canes Venatici Canes Venatici () is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...

with approximately 400 billion stars. M63 was first discovered by the French astronomer

Pierre Méchain Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets. Life Pierre Méchain was born i ...

, then later verified by his colleague

Charles Messier Charles Messier (; 26 June 1730 – 12 April 1817) was a French astronomer. He published an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the ''Messier objects''. Messier's purpose ...

on June 14, 1779. The galaxy became listed as object 63 in the

Messier Catalogue The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters''). Because Messier was only in ...

. In the mid-19th century, Anglo-Irish astronomer Lord Rosse identified spiral structures within the galaxy, making this one of the first galaxies in which such structure was identified. The shape or morphology of this galaxy has a classification of SAbc, indicating a spiral form with no central bar feature (SA) and moderate to loosely wound arms (bc). There is a general lack of large-scale continuous spiral structure in visible light, so it is considered a ''

flocculent galaxy A flocculent spiral galaxy is a type of spiral galaxy. Unlike the well-defined spiral architecture of a grand design spiral galaxy, flocculent (meaning "flaky") galaxies are patchy, with discontinuous spiral arms. Self-propagating star formatio ...

''. However, when observed in the

near infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from arou ...

, a symmetric, two-arm structure is seen. Each arm wraps 150° around the galaxy and extends out to from the nucleus. M63 is a weakly

active galaxy An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ...

with a

LINER A low-ionization nuclear emission-line region (LINER) is a type of galactic nucleus that is defined by its spectral line emission. The spectra typically include line emission from weakly ionized or neutral atoms, such as O, O+, N+, and S+. ...

nucleus – short for 'low-ionization nuclear emission-line region'. This displays as an unresolved source at the galactic nucleus that is cloaked in a diffuse emission. The latter is extended along a

position angle In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the north celestial pole (NCP), turning positive into the ...

of 110° relative to the

north celestial pole The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers at ...

, and both

soft X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 ...

s and hydrogen (

H-alpha H-alpha (Hα) is a specific deep-red visible spectral line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared wit ...

) emission can be observed coming from along nearly the same direction. The existence of a

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical ob ...

(SMBH) at the nucleus is uncertain; if it does exist, then the mass is estimated as , or around 850 million times the mass of the Sun. Radio observations at the 21-cm hydrogen line show the gaseous disk of M63 extends outward to a radius of , well past the bright optical disk. This gas shows a symmetrical form that is warped in a pronounced manner, starting at a radius of . The form suggests a

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not a ...

halo that is offset with respect to the inner region. The reason for the warp is unclear, but the position angle points toward the smaller companion galaxy, UGC 8313. The distance to M63, based upon the luminosity-distance measurement is . The radial velocity relative to the

Local Group The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form ...

yields an estimate of . Estimates based on the

Tully–Fisher relation In astronomy, the Tully–Fisher relation (TFR) is an empirical relationship between the mass or intrinsic luminosity of a spiral galaxy and its asymptotic rotation velocity or emission line width. It was first published in 1977 by astronomer ...

range over . The

tip of the red-giant branch Tip of the red-giant branch (TRGB) is a primary distance indicator used in astronomy. It uses the luminosity of the brightest red-giant-branch stars in a galaxy as a standard candle to gauge the distance to that galaxy. It has been used in conjun ...

technique gives a distance of . M63 is part of the

M51 Group The M51 Group is a group of galaxies located in Canes Venatici. The group is named after the brightest galaxy in the group, the Whirlpool Galaxy (M51A). Other notable members include the companion galaxy to the Whirlpool Galaxy ( M51B) and the S ...

, a group of galaxies that also includes

M51 M51 or M-51 may refer to: * M-51 (Michigan highway), a state highway in Michigan * M51 highway (Russia) * M51 (Cape Town), a Metropolitan Route in Cape Town, South Africa * M51 Skysweeper, an anti-aircraft gun * M51 MACI mine * M51 SLBM, a Fre ...

(the 'Whirlpool Galaxy'). In 1971, a supernova with a magnitude of 11.8 appeared in one of the arms. It was discovered on May 24 and reached peak light around May 26. The spectrum of this, , is consistent with a supernova of type I. However, the spectroscopic behavior appeared anomalous.

Gallery

File:Messier 63 GALEX WikiSky.jpg, M63 imaged in UV light by the GALEX satellite. The UV light is produced primarily by young, massive stars, so the UV-bright areas are regions where stars are currently forming. Credit

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

WikiSky Sky-Map.org (or WikiSky.org) is a wiki and interactive sky map that covers more than half a billion celestial objects. Users can view the whole star sky at once and zoom in to view areas in greater detail. WikiSky includes many stars, galaxies, ...

File:M63 3.6 8.0 24 microns spitzer.png, Messier 63 seen in the

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

by the Spitzer Space Telescope. The infrared radiation traces the dust within the spiral arms, which does not radiate visible light. A small dust ring can be seen just outside of the galaxy's center.

References

External links

*
Sunflower Galaxy @ SEDS Messier pages

Sunflower Galaxy (M63) at Constellation Guide
{{DEFAULTSORT:Messier 63 Unbarred spiral galaxies LINER galaxies M51 Group Canes Venatici 063 NGC objects 08334 46153 Astronomical objects discovered in 1779

Gallery

See also

References

External links