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Whirlpool Galaxy

Whirlpool Galaxy (M51A/B or NGC 5194/5). Credit: NASA/ESA
Observation data (J2000 epoch)
ConstellationCanes Venatici[1]
Right ascension13h 29m 52. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In common usage a constellation is a group of celestial bodies that are connected together in some arrangement typically stars to form a visible figure or picture Canes Venatici ( Hunting dogs) is a small northern Constellation that was introduced by Johannes Hevelius in the 17th century Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere 7s[2]
Declination+47° 11′ 43″[2]
Redshift463 ± 3 km/s[2]
Distance23 ± 4 Mly (7. In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either In Physics and Astronomy, redshift occurs when Electromagnetic radiation – usually Visible light – emitted or reflected by A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by 1 ± 1. 2 Mpc)[3]
TypeSA(s)bc pec[2]
Apparent dimensions (V)11′. History The first direct measurements of an object at interstellar distances were undertaken by German Astronomer Friedrich Wilhelm Bessel in 1838 Galaxy morphological classification is a system used by Astronomers to divide galaxies into groups based on their visual appearance The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle 2 × 6′. 9[2]
Apparent magnitude (V)9. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 0[2]
Notable featuresInteracting with NGC 5195[4]
Other designations
Question Mark Galaxy,[2] Rosse's Galaxy,[2] M51a,[2] NGC 5194,[2] UGC 8493,[2] PGC 47404,[2] VV 001a,[2] VV 403,[2] Arp 85[2]
See also: Galaxy, List of galaxies

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. NGC 5195 (also known as Messier 51b or M51b) is a Dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51a or NGC The Messier objects are a set of Astronomical objects first listed by French astronomer Charles Messier in his "Catalogue des Nébuleuses The New General Catalogue ( NGC) is the best-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 Catalogue of Principal Galaxies ( PGC) is an Astronomical catalogue published in 1989 that lists B1950 and J2000 Equatorial The Atlas of Peculiar Galaxies is a catalog of Peculiar galaxies produced by Halton Arp. A galaxy is a massive gravitationally bound system consisting of Stars an Interstellar medium of gas and dust, and Dark matter This is a list of notable galaxies. List 4C 3711 Abell 1835 IR1916 AM 0644-741 Interacting galaxies ( Colliding galaxies) are the result of one Galaxy 's Gravity disturbing another galaxy A grand design spiral galaxy is a type of Spiral galaxy with prominent and well-defined spiral arms as opposed to multi-arm and flocculent spirals which have subtler structural A spiral galaxy is a Galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by In common usage a constellation is a group of celestial bodies that are connected together in some arrangement typically stars to form a visible figure or picture Canes Venatici ( Hunting dogs) is a small northern Constellation that was introduced by Johannes Hevelius in the 17th century 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. NGC 5195 (also known as Messier 51b or M51b) is a Dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51a or NGC Amateur astronomy, a subset of Astronomy, is a Hobby whose participants enjoy studying and observing celestial objects Binocular telescopes, or binoculars (also known as field glasses are two identical or Mirror - symmetrical telescopes mounted side-by-side and [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. A spiral galaxy is a Galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the

Contents

Discovery

The Whirlpool Galaxy was discovered by Charles Messier on October 13, 1773. Charles Messier ( June 26, 1730 &ndash April 12, 1817) was a French astronomer most notable for publishing an Events 54 - Nero ascends to the Roman throne 409 - Vandals and Alans crossed the Pyrenees Year 1773 ( MDCCLXXIII) was a Common year starting on Friday (link will display the full calendar of the Gregorian calendar (or a Common Its companion galaxy, NGC 5195, was discovered in 1781 by Pierre Méchain. NGC 5195 (also known as Messier 51b or M51b) is a Dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51a or NGC Pierre François André Méchain ( August 16, 1744 &ndash September 20, 1804) was a French Astronomer and surveyor It was however not until 1845 that the Whirlpool became the first galaxy to be recognized as a spiral. This was achieved by Lord Rosse employing a 72-inch reflecting telescope which he constructed at Birr Castle, Ireland. William Parsons 3rd Earl of Rosse KP ( June 17, 1800 &ndash October 31, 1867) built the world's largest telescope in 1845 and it A reflecting telescope (also called a reflector) is an Optical telescope which uses a single or combination of Curved mirrors that reflect Light This article is about the castle in Birr the town in Ireland For alternative meanings see Birr (disambiguation. In 2005 a supernova (SN 2005cs) was observed in the Whirlpool Galaxy, peaking at apparent magnitude 14. A supernova (plural supernovae or supernovas) is a stellar Explosion. SN 2005cs was a Supernova in the Whirlpool Galaxy. It was a type II supernova discovered by a German amateur astronomer The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value [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).

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. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object Compared to 100 kly diameter of the Milky Way, M51 has about half its size and mass. The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Γαλαξίας (Galaxias sometimes referred to simply

"X" across the nucleus of M51 indicating two dust rings around the black hole at the center of the galaxy
"X" across the nucleus of M51 indicating two dust rings around the black hole at the center of the galaxy

A black hole surrounded by a ring of dust exists at the heart of the spiral. A black hole is a theoretical region of space in which the Gravitational field is so powerful that nothing not even Electromagnetic radiation (e 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. Ionisation cones are cones of material extending out from spiral galaxies. [9]

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. Canes Venatici ( Hunting dogs) is a small northern Constellation that was introduced by Johannes Hevelius in the 17th century This article is about the asterism; for other uses see Big Dipper (disambiguation. Eta Ursae Majoris (η UMa / η Ursae Majoris is a Star in the Constellation Ursa Major. 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. A circumpolar star is a star that as viewed from a given latitude on Earth never sets (that is never disappears below the horizon due to its proximity to one of the Celestial Solstices occur twice a year when the tilt of the Earth's axis is most oriented toward or away from the Sun, causing the Sun to reach its northernmost and southernmost extremes

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. An H II region (also known as Emission nebula) is a cloud of glowing Gas and plasma, sometimes several hundred Light-years across The shape of the X-formation in the nucleus has often been compared to the Christian cross. The Christian cross is the best-known Religious symbol of Christianity.

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 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 Messier 51b or M51b) is a Dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51a or NGC

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 and 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. In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus

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 stellar 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. For an object in the constellation of Canis Major also called Eagle nebula see Seagull Nebula.

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 came from behind M51 through the disk towards the observer and 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]. The M51 Group is a Group of galaxies located in Canes Venatici. Galaxy groups and clusters are the largest Gravitationally bound objects to have arisen thus far in the process of cosmic structure formation The Sunflower Galaxy (also known as Messier 63, M63, or NGC 5055) is an Unbarred spiral galaxy in the Canes Venatici Constellation [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. The M101 Group is a loose Group of galaxies located in Ursa Major. The NGC 5866 Group is a small Group of galaxies located in the Constellation Draco. [16]

See also

External links

References

  1. ^ R. NGC 5195 (also known as Messier 51b or M51b) is a Dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51a or NGC 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.  
  2. ^ 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. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1060 - Béla I of Hungary is crowned king of Hungary 1240 - Mongol invasion of Rus: Kiev
  3. ^ Takáts, K. ; Vinkó, J. (2006). "Distance estimate and progenitor characteristics of SN 2005cs in M51". Monthly Notices of the Royal Astronomical Society, Online Early: 1735. doi:10.1111/j.1365-2966.2006.10974.x. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  4. ^ a b H. Arp (1966). "Atlas of Peculiar Galaxies". Astrophysical Journal Supplement 14: 1-20. doi:10.1086/190147. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  5. ^ D. M. Elmegreen, B. G. Elmegreen (1987). "Arm classifications for spiral galaxies". Astrophysical Journal 314: 3-9. doi:10.1086/165034. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  6. ^ Nemiroff, Robert; Jerry Bonnell (2000-July-24). Astronomy Picture of the Day. nasa. gov. Retrieved on 2007-04-22. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1500 - Portuguese Navigator Pedro Álvares Cabral becomes the first European to sight Brazil.
  7. ^ MacRobert, Alan M. (August 24, 2005). Events 49 BC - Julius Caesar 's General Gaius Scribonius Curio is defeated in the Second Battle of the Bagradas River Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Supernova in M51. Sky Tonight. Sky and Telescope. Retrieved on August 7, 2006.
  8. ^ Bishop, David. Supernova 2005cs in M51. supernovae. net. Retrieved on August 7, 2006.
  9. ^ NASA's Hubble Space Telescope Resolves a Dark "x" Across the Nucleus of M51. News Center. HubbleSite (June 8, 1992). Events 68 - The Roman Senate accepts emperor Galba. 536 - St Silverius becomes Pope (probable Year 1992 ( MCMXCII) was a Leap year starting on Wednesday (link will display full 1992 Gregorian calendar) Retrieved on August 7, 2006.
  10. ^ Out of This Whirl: the Whirlpool Galaxy (M51) and Companion Galaxy. News Center. HubbleSite (April 25, 2005). Events 1607 - Eighty Years' War: The Dutch fleet destroys the anchored Spanish fleet at Gibraltar. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Retrieved on August 7, 2006.
  11. ^ Salo, Heikki; Laurikainen, Eija (1999). "A Multiple Encounter Model of M51". Astrophysics and Space Science 269/270: 663-664.  
  12. ^ R. B. Tully (1988). Nearby Galaxies Catalog. Cambridge: Cambridge University Press. ISBN 0-521-35299-1.  
  13. ^ 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.  
  14. ^ A. Garcia (1993). "General study of group membership. II - Determination of nearby groups". Astronomy and Astrophysics Supplement 100: 47-90.  
  15. ^ 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. doi:10.1086/317070. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  16. ^ 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. doi:10.1086/313391. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
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