Messier Index/M51 – Wikibooks, open books for an open world

Messier Index/M51 - Wikibooks, open books for an open world

The Whirlpool Galaxy (often known as Messier 51a, M51a, or NGC 5194) is an interacting[4]grand-design[5]w:spiral galaxy situated at a distance of roughly 31 million w:light-years within the w:constellation w:Canes Venatici. It is without doubt one of the most well-known spiral galaxies within the sky.[citation needed] The galaxy and its companion (w:NGC 5195) are simply noticed by newbie astronomers, and the 2 galaxies might even be seen with w:binoculars.[6] The Whirlpool Galaxy can also be a well-liked goal for skilled astronomers, who examine it to additional understanding of galaxy construction (notably construction related to the spiral arms) and galaxy interactions.


Sketch of M51 by Lord Rosse (William Parsons) in 1845

What was later often known as the Whirlpool Galaxy, was found[7] in 1774 by w:Charles Messier, and is designated as M51. Its companion galaxy, w:NGC 5195, was found in 1781 by w:Pierre Méchain. It was nevertheless not till 1845 that the Whirlpool grew to become the primary to be acknowledged as a spiral. This was achieved by Lord Rosse using a 72-inch (~1.83 m) reflecting telescope which he constructed at w:Birr Citadel, Eire. Generally M51 is used to seek advice from the pair of galaxies, by which case the person galaxies could also be known as M51A (NGC 5194) and M51B (NGC 5195).

In 2005 a w:supernova (w:SN 2005cs) was noticed within the Whirlpool Galaxy, peaking at w:obvious magnitude 14.[8][9]


With the latest SN 2008cs derived estimate of 23 Mly distance, and an angular diameter of roughly 11.2′, it may be inferred that M51’s brilliant round disk has a radius of about ~38,000 light-years. Its w:mass is estimated to be 160 billion photo voltaic lots.

thumb|proper|200px|The cross throughout the nucleus of M51 indicating two mud rings across the black gap on the heart of the nebulaA w:black gap, surrounded by a hoop of mud, is believed to exist on the coronary heart of the spiral. The mud ring stands nearly perpendicular to the comparatively flat spiral nebula. A secondary ring crosses the first ring on a special axis, a phenomenon that’s opposite to expectations. A pair of w:ionization cones lengthen from the axis of the principle mud ring.[10]

Visible look

Positioned throughout the constellation w:Canes Venatici, M51 is discovered by following the easternmost star of the w:Huge Dipper, w:Eta Ursae Majoris, and going 3.5° southeast. Its declination is +47°, making it a circumpolar for observers situated above 43°N latitude; it reaches excessive altitudes all through the northern hemisphere making it an accessible object from the early hours in winter by the tip of spring season, after which remark is hindered in decrease lattitudes.

M51 is seen by binoculars underneath darkish sky situations and may be resolved intimately with trendy newbie telescopes. When seen by a 100 mm telescope the fundamental outlines of M51 and its companion are seen. Beneath darkish skies, and with a average eyepiece by a 150 mm telescope, M51’s intrinsic spiral construction may be detected. With bigger (>300 mm) devices underneath darkish sky situations, the varied spiral bands are obvious with w:HII areas seen, and M51 may be seen to be hooked up to w:M51B.

As is common for galaxies, the true extent of its construction can solely be gathered from inspecting pictures; lengthy exposures reveal a big nebula extending past the seen round look.

In January 2005 the Hubble Heritage Crew constructed a 11477×7965 pixel composite picture (proven within the information field above) of M51 utilizing Hubble’s ACS instrument.[11]

Spiral construction

The very pronounced spiral construction of the Whirlpool Galaxy is believed to be the results of the shut interplay between it and its companion galaxy w:NGC 5195.

Star formation

Induced spiral construction within the bigger galaxy is not the one impact of the interplay. Vital compression of hydrogen gasoline happens that results in the event of starbirth areas. In footage of M51 these present up as the brilliant blue ‘knots’ all through the spiral arms.

Typically talking, hydrogen gasoline is the most typical element of the w:interstellar medium (the huge house between stars and planetary methods in galaxies). It exists primarily in its atomic and molecular type, and kinds enormous clouds all through your entire galaxy. When giant sources of gravitational pull go close by, equivalent to different galaxies, gravitational interactions produce compression (density) waves that sweep by these hydrogen clouds. This causes some areas of the beforehand diffuse gasoline to compress into tight pockets of opaque and dense gasoline, these are mud lanes one so typically sees within the spiral arms. In areas the place the focus and density of gasoline reaches a crucial worth, additional collapse underneath its personal gravitational pull happens, and stars are born on the heart of the collapse, the place the gasoline is compressed so strongly that fusion initiates.

When this occurs, these new-born stars gobble up enormous quantities of gasoline inflicting them to develop, shine even hotter, and eventually sweep away the encircling layers of mud and gasoline by rising efflux of the stellar wind. The large proportions of the clouds out of which they’re born means stars seldom, if ever, are created in isolation. Thus areas of a number of scorching younger stars emit ample gentle vitality that they are often seen within the excessive decision footage of M51 throughout thousands and thousands of lightyears distance.

For an instance of such a formation in our personal galaxy, see M16, the w:Eagle Nebula.


Many years in the past, it was not identified with certainty whether or not the companion galaxy NGC 5195 was a real companion, or one other galaxy passing at a distance. The arrival of radio astronomy and subsequent radio photographs of M51 unequivocally demonstrated the truth of the interplay.

Latest simulations bear out that M51’s spiral construction was brought on by NGC 5195 passing by the principle disk of M51 about 500 to 600 million years in the past. On this mannequin,[12]
NGC 5195 got here from behind M51 by the disk in direction of the observer and made one other disk crossing as just lately as 50 to 100 Myrs in the past till it’s the place we observe it to be now, barely behind M51.

Galaxy group info

The Whirlpool Galaxy is the brightest galaxy within the w:M51 Group, a small w:group of galaxies that additionally contains M63 (the Sunflower Galaxy), w:NGC 5023, and w:NGC 5229.[13][14][15][16] This small group may very well be a subclump on the southeast finish of a big, elongated group that features the w:M101 Group and the w:NGC 5866 Group, though most group identification strategies and catalogs determine the three teams as separate entities.[17]

M51 in Fiction

This galaxy is featured within the “w:Homeworld” RTS Franchise, which is house to a human-like race of beings referred to as “Hiigarans”.
This galaxy can also be in “w:The Genesis Quest” and “w:Second Genesis” by w:Donald Moffitt, and is the house galaxy for the aliens often known as “The Nar”.


  1. R. W. Sinnott, editor (1988). The Full New Normal Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Company and Cambridge College Press. ISBN 0-933-34651-4. 
  2. abcdefghijoklmno “NASA/IPAC Extragalactic Database”. Outcomes for NGC 5194. Retrieved 2006-12-06. 
  3. Takáts, Ok.; Vinkó, J. (2006). “Distance estimate and progenitor traits of SN 2005cs in M51”. Month-to-month Notices of the Royal Astronomical Society, On-line Early 372: 1735. doi:10.1111/j.1365-2966.2006.10974.x. 
  4. ab H. Arp (1966). “Atlas of Peculiar Galaxies”. Astrophysical Journal Complement 14: 1–20. doi:10.1086/190147.…14….1A. 
  5. D. M. Elmegreen, B. G. Elmegreen (1987). “Arm classifications for spiral galaxies”. Astrophysical Journal 314: 3–9. doi:10.1086/165034.…314….3E. 
  6. Nemiroff, Robert; Jerry Bonnell (2000-07-24). “Astronomy Image of the Day”. Retrieved 2007-04-22. 
  7. Catalogue des Nébuleuses & des amas d’Étoiles.” by Charles Messier, Connoissance des Temps for 1784 (printed 1781), pp. 227-267 (web page 246) [Bibcode: 1781CdT..1784..227M]
  8. MacRobert, Alan M. (w:August 24 w:2005). “Supernova in M51”. Sky Tonight. Sky and Telescope. Retrieved August 7, 2006. 
  9. Bishop, David. “Supernova 2005cs in M51”. supernovae.web. http://www.supernovae.web/sn2005/sn2005cs.html. Retrieved August 7, 2006. 
  10. “NASA’s Hubble House Telescope Resolves a Darkish “x” Throughout the Nucleus of M51″. Information Middle. HubbleSite. w:June eight w:1992. content/. Retrieved August 7, 2006. 
  11. “Out of This Whirl: the Whirlpool Galaxy (M51) and Companion Galaxy”. Information Middle. HubbleSite. w:April 25 w:2005. Retrieved August 7, 2006. 
  12. Salo, Heikki; Laurikainen, Eija (1999). “A A number of Encounter Mannequin of M51”. Astrophysics and House Science 269/270: 663–664. doi:10.1023/A:1017002909665. 
  13. R. B. Tully (1988). Close by Galaxies Catalog. Cambridge: Cambridge College Press. ISBN 0-521-35299-1. 
  14. P. Fouque, E. Gourgoulhon, P. Chamaraux, G. Paturel (1992). “Teams of galaxies inside 80 Mpc. II – {The catalogue} of teams and group members”. Astronomy and Astrophysics Complement 93: 211–233.…93..211F. 
  15. A. Garcia (1993). “Normal examine of group membership. II – Willpower of close by teams”. Astronomy and Astrophysics Complement 100: 47–90.…47G. 
  16. G. Giuricin, C. Marinoni, L. Ceriani, A. Pisani (2000). “Close by Optical Galaxies: Choice of the Pattern and Identification of Teams”. Astrophysical Journal 543: 178–194. doi:10.1086/317070.…543..178G. 
  17. 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. Ok. Gibson, J. A. Graham, S. M. Hughes, G. D. Illingworth, D. D. Kelson, L. Macri, Ok. Sebo, N. A. Silbermann (2000). “A Database of Cepheid Distance Moduli and Tip of the Purple Big Department, Globular Cluster Luminosity Operate, Planetary Nebula Luminosity Operate, and Floor Brightness Fluctuation Knowledge Helpful for Distance Determinations”. Astrophysical Journal Complement 128: 431–459. doi:10.1086/313391. 

Exterior hyperlinks

Related posts

Leave a Comment