NationMaster - Encyclopedia: Whirlpool Galaxy

The Whirlpool Galaxy (also known as Messier 51a, M51a, or NGC 5194) is an interacting^[4] grand-design^[5] spiral galaxy located at a distance of approximately 23 million light-years in the constellation Canes Venatici. It is one of the most famous spiral galaxies in the sky. The galaxy and its companion (NGC 5195) are easily observed by amateur astronomers, and the two galaxies may even be seen with binoculars.^[6] The Whirlpool Galaxy is also a popular target for professional astronomers, who study it to further understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions. The J2000. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... This article does not cite any references or sources. ... Canes Venatici (Latin for Hunting dogs) is a small northern constellation that was introduced by Johannes Hevelius in the 17th century. ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (abbrev. ... Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared with that of the Sun (left). ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... (Redirected from 1 E23 m) Categories: Orders of magnitude (length) ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... A parsec is the distance from the Earth to an astronomical object which has a parallax angle of one arcsecond. ... Astronomers classify galaxies based on their overall shape (elliptical, spiral or barred spiral) and further by the specific properties of the individual galaxy (for example degree of ellipse, number of spirals or definition of bar). ... The angular diameter of an object as seen from a given position is the diameter measured as an angle. ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... NGC 5195 (also known as M51B) is a dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51A or NGC 5194). ... The Messier objects are a set of astronomical objects catalogued by Charles Messier in his catalogue of Nebulae and Star Clusters first published in 1774. ... The New General Catalogue (NGC) is the most well-known catalogue of deep sky objects in amateur astronomy. ... The Uppsala General Catalogue of Galaxies (UGC) is a catalogue of 12921 galaxies visible from the northern hemisphere. ... The Principal Galaxies Catalogue (PGC) is an astronomical catalogue that contains all available primary information for each of the known galaxies: morphological type, major and minor axes, magnitude, radial velocity and position angle. ... The Antennae Galaxies (Arp 244) The Atlas of Peculiar Galaxies (APG, majoraly called Arp galaxies) is a catalog of peculiar galaxies produced by Halton Arp. ... For other uses, see Galaxy (disambiguation). ... List of galaxies: Abell 1835 IR1916 AM 0644-741 Andromeda Galaxy (M31/NGC 224) Andromeda I Andromeda II Andromeda III Aquarius Dwarf Barnards Galaxy (NGC 6822) Black Eye Galaxy (M64/NGC 4826) Bodes Galaxy (M81/NGC 3031) Canis Major Dwarf Galaxy Carina Dwarf Centaurus A Galaxy Draco Dwarf Fornax... Interacting galaxies (Colliding galaxies) is the result of gravity of two close galaxies. ... A Spitzer Space Telescope Image of Mesier 81, a grand design spiral Grand design spiral galaxies are a type of spiral galaxy known for their prominent and well-defined spiral arms, as opposed to multi-arm and flocculent spirals which have subtler structural features. ... It has been suggested that spiral nebula be merged into this article or section. ... (Redirected from 1 E23 m) Categories: Orders of magnitude (length) ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... This article does not cite any references or sources. ... Canes Venatici (Latin for Hunting dogs) is a small northern constellation that was introduced by Johannes Hevelius in the 17th century. ... NGC 5195 (also known as M51B) is a dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51A or NGC 5194). ... It has been suggested that this article or section be merged with Skygazing. ... Porro-prism binoculars with central focusing Binocular telescopes, or binoculars, (also known as field glasses) are two identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. ... It has been suggested that spiral nebula be merged into this article or section. ...

Discovery

The Whirlpool Galaxy was discovered by Charles Messier on October 13, 1773. Its companion galaxy, NGC 5195, was discovered in 1781 by Pierre Méchain. It was not until 1845 that the Whirlpool Galaxy became the first to be recognized as a spiral. This was achieved by Lord Rosse using a 72-inch reflecting telescope he had constructed at Birr Castle, Ireland. In 2005 a supernova (SN 2005cs) was observed in the Whirlpool Galaxy, peaking at apparent magnitude 14.^[7]^[8] Sometimes M51 is used to refer to the pair of galaxies, in which case the individual galaxies may be referred to as M51A (NGC 5194) and M51B (NGC 5195). Charles Messier Charles Messier (June 26, 1730 â€“ April 12, 1817) was a French astronomer who in 1774 published a catalogue of 45 deep sky objects such as nebulae and star clusters. ... is the 286th day of the year (287th in leap years) in the Gregorian calendar. ... 1773 was a common year starting on Friday (see link for calendar). ... NGC 5195 (also known as M51B) is a dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51A or NGC 5194). ... 1781 was a common year starting on Monday (see link for calendar). ... Pierre FranÃ§ois AndrÃ© MÃ©chain (August 16, 1744 â€“ September 20, 1804) was a French astronomer. ... Lord Rosse William Parsons, 3rd Earl of Rosse KP (June 17, 1800 â€“ October 31, 1867) was born in Monkstown, County Cork and was an Irish astronomer. ... Ritchey 24 reflecting telescope A reflecting telescope (reflector) is an optical telescope which uses mirrors, rather than lenses, to reflect light. ... The castle. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... Supernova SN2005cs SN 2005cs was a supernova in the Whirlpool Galaxy. ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ...

Image File history File links M51Sketch. ... Image File history File links M51Sketch. ... Lord Rosse William Parsons, 3rd Earl of Rosse KP (June 17, 1800 â€“ October 31, 1867) was born in Monkstown, County Cork and was an Irish astronomer. ...

Properties

With the recent SN 2005cs derived estimate of 23 Mly distance, and an angular diameter of roughly 11′.2, we can infer that M51's bright circular disk has a radius of about ~38,000 light-years. Its mass is estimated to be 160 billion solar masses. Compared to 100 kly diameter of the Milky Way, M51 has about half its size and mass. This article or section is in need of attention from an expert on the subject. ... For other uses, see Milky Way (disambiguation). ...

A black hole surrounded by a ring of dust exists at the heart of the spiral. The dust ring stands almost perpendicular to the relatively flat spiral galaxy. A secondary ring crosses the primary ring on a different axis, a phenomenon that is contrary to expectations. A pair of ionization cones extend from the axis of the main dust ring.^[9] Image File history File links Download high-resolution version (2169x2025, 92 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Whirlpool Galaxy ... Image File history File links Download high-resolution version (2169x2025, 92 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Whirlpool Galaxy ... For other uses, see Black hole (disambiguation). ...

Visual appearance

Located within the constellation Canes Venatici, M51 is easy to find by following the easternmost star of the Big Dipper, Eta Ursae Majoris, and going 3.5° southeast. Its declination is +47°, so it is circumpolar for observers located above 43°N latitude and reaches high altitudes throughout the northern hemisphere making it an accessible object, especially from the very early hours in winter through the end of spring season, after which summer solstice somewhat hinders observations. Canes Venatici (Latin for Hunting dogs) is a small northern constellation that was introduced by Johannes Hevelius in the 17th century. ... Big Dipper map A group of the brightest stars of the constellation Ursa Major, the Great Bear, form a well-known asterism that has been recognized as a distinct grouping in many cultures from time immemorial. ... Eta Ursae Majoris (Î· UMa / Î· Ursae Majoris) is a star in the constellation Ursa Major. ... â€œSummer solsticeâ€ redirects here. ...

M51 is visible through binoculars on a dark night, but with modern amateur telescopes this galaxy is truly a sight to behold. It is very forgiving on the instrument, when seen even through a humble 10 cm telescope the basic outlines of M51 and its companion are visible. Under dark skies and seen with a moderate eyepiece through a 15 cm telescope one can detect M51's intrinsic spiral structure. With larger (>30 cm) instruments M51 is simply breathtaking. The various spiral bands are very obvious and several HII regions appear to be visible, and M51 can be seen to be attached to M51B. NGC 604, a giant H II region in the Triangulum Galaxy. ...

As is usual for galaxies, the true extent of its size can only be gathered from inspecting deep photographs, and very long exposures reveal a pretty large nebula extending beyond the visible circular appearance.

In January 2005 the Hubble Heritage Team constructed a 11477x7965 pixel composite image (shown in the info box above) of M51 using Hubble's ACS instrument, revealing this splendid galaxy and its companion in unprecedented detail.^[10]

Spiral structure

The very pronounced spiral structure of the Whirlpool Galaxy is believed to be the result of the close interaction between it and its companion galaxy NGC 5195. NGC 5195 (also known as M51B) is a dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51A or NGC 5194). ...

Star formation

Induced spiral structure in the larger galaxy isn't the only effect of the interaction. Significant compression of hydrogen gas occurs that leads to the development of starbirth regions. In pictures of M51 these show up as the bright blue 'knots' throughout the spiral arms.

Generally speaking, hydrogen gas is the most common component of the interstellar medium (the vast space between stars & planetary systems in galaxies). It exists primarily in its atomic and molecular form, and forms huge clouds throughout the entire galaxy. When large sources of gravitational pull pass nearby, such as other galaxies, gravitational interactions produce compression (density) waves that sweep through these hydrogen clouds. This causes some regions of the previously diffuse gas to compress into tight pockets of opaque and dense gas, these are dust lanes one so often sees in the spiral arms. In regions where the concentration and density of gas reaches a critical value, further collapse under its own gravitational pull occurs, and stars are born at the center of the collapse, where the gas is compressed so strongly that fusion initiates. The interstellar medium (or ISM) is the name astronomers give to the tenuous gas and dust that pervade interstellar space. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...

When this happens, these new-born stars gobble up huge amounts of gas causing them to expand, shine even hotter, and finally sweep away the surrounding layers of dust and gas by increasing efflux of the solar wind. The gigantic proportions of the clouds out of which they are born means stars seldom, if ever, are created in isolation. Thus regions of several hot young stars emit sufficient light energy that they can be seen in the high resolution pictures of M51 across millions of lightyears distance.

For an example of such a formation in our own galaxy, see M16, the Eagle Nebula. The Eagle Nebula (also known as Messier Object 16, M16 or NGC 6611), perhaps one of the most famous and easily recognized space objects, is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. ...

Companion

Decades ago, it wasn't known for certain if the companion galaxy NGC 5195 was actually a true companion or rather some other galaxy passing at a distance. The advent of radio astronomy and subsequent radio images of M51 unequivocally demonstrated the reality of the interaction.

Recent simulations bear out that M51's spiral structure was caused by NGC 5195 passing through the main disk of M51 about 500 to 600 million years ago. In this model,^[11] NGC 5195 comes from behind M51 through the disk towards the observer, made another disk crossing as recently as 50 to 100 Myrs ago until it is where we observe it to be now, slightly behind M51.

Galaxy group information

The Whirlpool Galaxy is the brightest galaxy in the M51 Group, a small group of galaxies that also includes M63 (the Sunflower Galaxy), NGC 5023, and NGC 5229^[12]^[13].^[14]^[15] This small group may actually be a subclump at the southeast end of a large, elongated group that includes the M101 Group and the NGC 5866 Group, although most group identification methods and catalogs identify the three groups as separate entities.^[16] Wikipedia does not yet have an article with this exact name. ... This article or section does not cite its references or sources. ... The Sunflower Galaxy (also known as Spiral Galaxy M63, Messier Object 63, Messier 63, M63, or NGC 5055) is a spiral galaxy in the Canes Venatici constellation. ... The M101 group of galaxies (or simply the M101 group) is a physical group and a galaxy cluster that comprises three of the most famous galaxies in the northern sky: M51, M101 and M63. ... Wikipedia does not yet have an article with this exact name. ...

Trivia

In the Homeworld series of games, the story is set within the M51 galaxy. For the term used in science-fiction, see Core worlds. ...

See also

Image File history File links Commons-logo. ... NGC 5195 (also known as M51B) is a dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51A or NGC 5194). ... Messier Object 101, the Pinwheel Galaxy. ...

External links

References

^ R. W. Sinnott, editor (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Corporation and Cambridge University Press. ISBN 0-933-34651-4.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o NASA/IPAC Extragalactic Database. Results for NGC 5194. Retrieved on 2006-12-06.
^ Takáts, K.; Vinkó, J. (2006). "Distance estimate and progenitor characteristics of SN 2005cs in M51". Monthly Notices of the Royal Astronomical Society, Online Early.
^ ^a ^b H. Arp (1966). "Atlas of Peculiar Galaxies". Astrophysical Journal Supplement 14: 1-20.
^ D. M. Elmegreen, B. G. Elmegreen (1987). "Arm classifications for spiral galaxies". Astrophysical Journal 314: 3-9.
^ Nemiroff, Robert; Jerry Bonnell (2000-July-24). Astronomy Picture of the Day. nasa.gov. Retrieved on 2007-04-22.
^ MacRobert, Alan M. (August 24, 2005). Supernova in M51. Sky Tonight. Sky and Telescope. Retrieved on August 7, 2006.
^ Bishop, David. Supernova 2005cs in M51. supernovae.net. Retrieved on August 7, 2006.
^ NASA's Hubble Space Telescope Resolves a Dark "x" Across the Nucleus of M51. News Center. HubbleSite (June 8, 1992). Retrieved on August 7, 2006.
^ Out of This Whirl: the Whirlpool Galaxy (M51) and Companion Galaxy. News Center. HubbleSite (April 25, 2005). Retrieved on August 7, 2006.
^ Salo, Heikki; Laurikainen, Eija (1999). "A Multiple Encounter Model of M51". Astrophysics and Space Science 269/270: 663-664.
^ R. B. Tully (1988). Nearby Galaxies Catalog. Cambridge: Cambridge University Press. ISBN 0-521-35299-1.
^ P. Fouque, E. Gourgoulhon, P. Chamaraux, G. Paturel (1992). "Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members". Astronomy and Astrophysics Supplement 93: 211-233.
^ A. Garcia (1993). "General study of group membership. II - Determination of nearby groups". Astronomy and Astrophysics Supplement 100: 47-90.
^ G. Giuricin, C. Marinoni, L. Ceriani, A. Pisani (2000). "Nearby Optical Galaxies: Selection of the Sample and Identification of Groups". Astrophysical Journal 543: 178-194.
^ L. Ferrarese, H. C. Ford, J. Huchra, R. C. Kennicutt Jr., J. R. Mould, S. Sakai, W. L. Freedman, P. B. Stetson, B. F. Madore, B. K. Gibson, J. A. Graham, S. M. Hughes, G. D. Illingworth, D. D. Kelson, L. Macri, K. Sebo, N. A. Silbermann (2000). "A Database of Cepheid Distance Moduli and Tip of the Red Giant Branch, Globular Cluster Luminosity Function, Planetary Nebula Luminosity Function, and Surface Brightness Fluctuation Data Useful for Distance Determinations". Astrophysical Journal Supplement 128: 431-459.

Categories: Spiral galaxies | Unbarred spiral galaxies | Interacting galaxies | Peculiar galaxies | M51 Group | Canes Venatici constellation | Messier objects | NGC objects | UGC objects | PGC objects | Arp objects Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... December 6 is the 340th day of the year (341st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 112th day of the year (113th in leap years) in the Gregorian calendar. ... is the 236th day of the year (237th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 159th day of the year (160th in leap years) in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ... is the 115th day of the year (116th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

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