The Whirlpool Galaxy, also known as Messier 51a, M51a, and NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus.[6][5][7] It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy.[8] Its distance is estimated to be 31 million light-years away from Earth.[9]
The galaxy and its companion, NGC 5195,[10] are easily observed by amateur astronomers, and the two galaxies may be seen with binoculars.[11] The Whirlpool Galaxy has been extensively observed by professional astronomers, who study it to understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions.
Discovery
Sketch of M51 by Lord Rosse in 1845
What later became known as the Whirlpool Galaxy was discovered on October 13, 1773, by Charles Messier while hunting for objects that could confuse comet hunters, and was designated in Messier's catalogue as M51.[12] Its companion galaxy, NGC 5195, was discovered in 1781 by Pierre Méchain, although it was not known whether it was interacting or merely another galaxy passing at a distance. In 1845, William Parsons, 3rd Earl of Rosse, employing a 72-inch (1.8 m) reflecting telescope at Birr Castle, Ireland, found that the Whirlpool possessed a spiral structure, the first "nebula" to be known to have one.[13] These "spiral nebulae" were not recognized as galaxies until Edwin Hubble was able to observe Cepheid variables in some of these spiral nebulae, which provided evidence that they were so far away that they must be entirely separate galaxies even though they are seen close together.[14]
The advent of radio astronomy and subsequent radio images of M51 unequivocally demonstrated that the Whirlpool and its companion galaxy are indeed interacting. Sometimes the designation 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).
Visual appearance
The image of the Whirlpool Galaxy in visible light (left) and infrared light (right)
Deep in the constellation Canes Venatici, M51 is often found by finding the easternmost star of the Big Dipper, Eta Ursae Majoris, and going 3.5° southwest. Its declination is, rounded, +47°, making it a circumpolar (never setting) for observers above the 43rd parallel north;[a] it reaches a high altitude throughout this hemisphere making it an accessible object from the early hours in November through to the end of May, after which observation is more coincidental in modest latitudes with the risen sun (due to the Sun approaching to and receding from its Right Ascension, specifically figuring in Gemini, just to the north).
M51 is visible through binoculars under dark sky conditions, and it can be resolved in detail with modern amateur telescopes.[11] When seen through a 100 mm telescope the basic outlines of M51 (limited to 5×6') and its companion are visible. Under dark skies, and with a moderate eyepiece through a 150 mm telescope, M51's intrinsic spiral structure can be detected. With larger (>300 mm) instruments under dark sky conditions, the various spiral bands are apparent with HII regions visible, and M51 can be seen to be attached to M51B.
As is usual for galaxies, the true extent of its structure can only be gathered from inspecting photographs; long exposures reveal a large nebula extending beyond the visible circular appearance. In 1984, thanks to the high-speed detector—the so-called image-photon-counting- IPCS—system—developed jointly by the CNRS Laboratoire d'Astronomie Spatiald (L.A.S.- CNRS) and the Observatoire de Haute Provence (O.H.P.) along with the particularly nice seeing offered by the Canada-France-Hawaii-Telescope (C.F.H.T.) 3.60m Cassegrain focus at Mauna Kea summit in Hawaii, Hua et al. detected the double component of the very nucleus of the Whirlpool galaxy (article in Astrophysical Letters and Communications, 1987, vol. 25, pp. 187–204).
In January 2005 the Hubble Heritage Project constructed a 11477 × 7965-pixel composite image (shown in the infobox above) of M51 using Hubble's ACS instrument. The image highlights the galaxy's spiral arms, and shows detail into some of the structures inside the arms.[15]
Whirlpool Galaxy – Observed in Various Light
a) 0.4; 0.7 μm – b) vis-blue/green; ir-red – c) 3.6; 4.5; 8 μm – d) 24 μm
Properties
Whirlpool Galaxy lies 23 million (31 million?)light-years from Earth and has an estimated diameter of 76,000 light-years. Overall the galaxy is about 43% the size of the Milky Way. Its mass is estimated to be 160 billion solar masses.[16] or around 10.3% of the mass of Milky Way Galaxy.
A black hole, once thought to be surrounded by a ring of dust, but now believed to be partially occluded by dust instead, exists at the heart of the spiral. A pair of ionization cones extend from the active galactic nucleus.[17]
Spiral structure
The 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, which may have passed through the main disk of M51 about 500 to 600 million years ago. In this proposed scenario, NGC 5195 came from behind M51 through the disk towards the observer and made another disk crossing as recently as 50 to 100 million years ago until it is where we observe it to be now, slightly behind M51.[18]
Star formation
The central region of M51 appears to be undergoing a period of enhanced star formation. The present efficiency of star formation, defined as the ratio of mass of new stars to the mass of star-forming gas, is only ~1%, quite comparable to the global value for the Milky Way and other galaxies. It is estimated that the current high rate of star formation can last no more than another 100 million years or so.[19]
Transient events
Three supernovae have been observed in the Whirlpool Galaxy:[20]
In 1994, SN 1994I was observed in the Whirlpool Galaxy. It was classified as type Ic, indicating that its progenitor star was very massive and had already shed much of its mass, and its brightness peaked at apparent magnitude 12.91.[21]
In June 2005 the type II supernova SN 2005cs was observed in the Whirlpool Galaxy, peaking at apparent magnitude 14.[22][23]
On 31 May 2011 a type II supernova was detected in the Whirlpool Galaxy, peaking at magnitude 12.1.[24] This supernova, designated SN 2011dh, showed a spectrum much bluer than average, with P Cygni profiles, which indicate rapidly expanding material, in its hydrogen-Balmer lines.[25] The progenitor was probably a yellow supergiant[26] and not a red or blue supergiant, which are thought to be the most common supernova progenitors.
On 22 January 2019, a supernova impostor, designated AT2019abn, was discovered in Messier 51. The transient was later identified as a luminous red nova. The progenitor star was detected in archival Spitzer Space Telescope infrared images. No object could be seen at the position of the transient in archival Hubble images, indicating that the progenitor star was heavily obstructed by interstellar dust. 2019abn peaked at magnitude 17, reaching an intrinsic brightness of M r = − 14.9 {\displaystyle M_{r}=-14.9} {\displaystyle M_{r}=-14.9}.[27]
Planet candidate
In September 2020, the detection of a candidate exoplanet, named M51-ULS-1b, orbiting the high-mass X-ray binary M51-ULS-1 in this galaxy was announced. If confirmed, it would be the first known instance of an extragalactic planet, a planet outside the Milky Way Galaxy. The planet was detected by eclipses of the X-ray source (XRS), which consists of a stellar remnant (either a neutron star or a black hole) and a massive star, likely a B-type supergiant. The planet would be slightly smaller than Saturn and orbit at a distance of some tens of astronomical units.[28][29]
Companion
Main article: 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 5194). Both galaxies are located approximately 25 million light-years away in the constellation Canes Venatici. Together, the two galaxies are one of the most widely studied interacting galaxy pairs.
Galaxy group information
Main article: M51 Group
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.[30][31][32][33] 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.[34]
Gallery
A 1992 Hubble image showing a knot of dust once thought to be a pair of rings encircling a black hole
A 2005 Hubble image showing details of the dust at the nucleus of M51
Supernova impostor AT2019abn, imaged at Northolt Branch Observatories in March 2019
Supernova impostor AT2019abn, imaged by the Hubble Space Telescope
Deep image of M51 – Whirlpool Galaxy using amateur astrophotography equipment
M51 (Whirlpool Galaxy) imaged by W4SM with 17" PlaneWave CDK scope, Louisa, VA.
Hubble Space Telescope image of Whirlpool Galaxy. Unrelated objects have been edited out.
See also
List of galaxies
List of Messier objects
Messier object
Messier 101 – another grand-design spiral galaxy
M51 in fiction* New General Catalogue
NGC 5195 – the companion galaxy to NGC 5194
References and footnotes
Dreyer, J. L. E. (1988). Sinnott, R. W. (ed.). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters. Sky Publishing Corporation/Cambridge University Press. ISBN 978-0-933346-51-2.
"NASA/IPAC Extragalactic Database". Results for NGC 5194. Retrieved December 6, 2006.
https://www.nasa.gov/feature/goddard/2017/messier-51-the-whirlpool-galaxy
"M51". SEDS.org.
Elmegreen, D. M.; Elmegreen, B. G. (1987). "Arm classifications for spiral galaxies". Astrophysical Journal. 314: 3–9. Bibcode:1987ApJ...314....3E. doi:10.1086/165034.
Arp, H. (1966). "Atlas of Peculiar Galaxies". Astrophysical Journal Supplement. 14: 1. Bibcode:1966ApJS...14....1A. doi:10.1086/190147.
Matsushita, Satoki; Muller, Sebastien; Lim, Jeremy (9 April 2007). "Jet-disturbed molecular gas near the Seyfert 2 nucleus in M51". Astronomy & Astrophysics. 468 (A&A Letters Special Issue): L49–L52. arXiv:0704.0947. Bibcode:2007A&A...468L..49M. doi:10.1051/0004-6361:20067039. S2CID 15471799.
"Whirlpool Galaxy: First Spiral Galaxy". Universe for Facts. Retrieved 21 December 2014.
Garner, Rob (2017-10-06). "Messier 51 (The Whirlpool Galaxy)". NASA. Retrieved 2021-01-20.
"M 51". 2016-10-10.
Nemiroff, R.; Bonnell, J., eds. (February 24, 2013). "M51: The Whirlpool Galaxy". Astronomy Picture of the Day. NASA. Retrieved October 11, 2018.
Messier, Charles (1781). "Catalogue des Nébuleuses & des amas d'Étoiles". Connaissance des Temps [1784]. pp. 227–267 [246].
Rosse revealed the spiral structure of Whirlpool galaxy (M51) at the 1845 meeting of the British Association for the Advancement of Science. Rosse's illustration of M51 was reproduced in J.P. Nichol's book of 1846.
Rosse, Earl of (1846). "On the nebula 25 Herschel, or 61 [should read: 51] of Messier's catalogue". Report of the Fifteenth Meeting of the British Association for the Advancement of Science; Held at Cambridge in June 1845 § Notices and Abstracts of Miscellaneous Communications to the Sections: 4.
Nichol, John Pringle (1846). Thoughts on Some Important Points Relating to the System of the World. Edinburgh, Scotland: William Tait. p. 23. Rosse's illustration of the Whirlpool galaxy appears on the plate that immediately precedes p. 23.
Hubble, E. P. (1929). "A spiral nebula as a stellar system, Messier 31". Astrophysical Journal. 69: 103–158. Bibcode:1929ApJ....69..103H. doi:10.1086/143167.
"Out of This Whirl: the Whirlpool Galaxy (M51) and Companion Galaxy". News Center. HubbleSite. April 25, 2005. Retrieved August 7, 2006.
"Whirlpool Galaxy". Herschel Space Observatory. Cardiff University. June 19, 2009. Retrieved October 11, 2018.
"NASA's Hubble Space Telescope Resolves a Dark "x" Across the Nucleus of M51". News Center. HubbleSite. June 8, 1992. Retrieved August 7, 2006.
Salo, Heikki; Laurikainen, Eija (1999). "A Multiple Encounter Model of M51". Astrophysics and Space Science. 269: 663–664. Bibcode:1999Ap&SS.269..663S. doi:10.1023/A:1017002909665. S2CID 189838328.
Thronson, Harley A.; Greenhouse, Matthew A. (1988). "Near-Infrared Mass-to-light ratios in Galaxies: Stellar Mass and Star Formation in the Heart of the Whirlpool". The Astrophysical Journal. 327: 671–679. Bibcode:1988ApJ...327..671T. doi:10.1086/166224.
"List of Supernovae". Central Bureau for Astronomical Telegrams. Retrieved February 27, 2016.
Sauer, D. N.; Mazzali, P. A.; Deng, J.; Valenti, S.; et al. (2006). "The properties of the 'standard' Type Ic supernova 1994I from spectral models". Monthly Notices of the Royal Astronomical Society. 369 (4): 1939–1948. arXiv:astro-ph/0604293. Bibcode:2006MNRAS.369.1939S. doi:10.1111/j.1365-2966.2006.10438.x. S2CID 119510845.
MacRobert, Alan M. (August 24, 2005). "Supernova in M51". Sky Tonight. Sky and Telescope. Retrieved August 7, 2006.
Bishop, David. "Supernova 2005cs in M51". supernovae.net. Archived from the original on October 3, 2006. Retrieved August 7, 2006.
Bishop, David. "Supernovae 2011dh in M51". supernovae.net (International Supernovae Network). Retrieved 2011-06-06.
Kinne (kqr), Richard (2011-06-03). "AAVSO Special Notice #241: New Supernova in M51". AAVSO. Retrieved 2011-06-06.
"ATEL 3401: Properties of the Candidate Progenitor of SN 2011dh in M51". Astronomers Telegram. 2011-06-03. Retrieved 2011-06-06.
Jacob E. Jencson; Scott M. Adams; Howard E. Bond (2019). "Discovery of an intermediate-luminosity red transient in M51 and its likely dust-obscured, infrared-variable progenitor". The Astrophysical Journal Letters. 880 (L20): L20. arXiv:1904.07857. Bibcode:2019ApJ...880L..20J. doi:10.3847/2041-8213/ab2c05. S2CID 119110002.
Crane, Leah (23 September 2020). "Astronomers may have found the first planet in another galaxy". New Scientist. Retrieved 25 September 2020.
Di Stafano, R.; et al. (18 September 2020). "M51-ULS-1b: The First Candidate for a Planet in an External Galaxy". arXiv:2009.08987 [astro-ph.HE].
Tully, R. B. (1988). Nearby Galaxies Catalog. Cambridge University Press. ISBN 978-0-521-35299-4.
Fouque, P.; Gourgoulhon, E.; Chamaraux, P.; Paturel, G. (1992). "Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members". Astronomy and Astrophysics Supplement. 93: 211–233. Bibcode:1992A&AS...93..211F.
Garcia, A. (1993). "General study of group membership. II - Determination of nearby groups". Astronomy and Astrophysics Supplement. 100: 47–90. Bibcode:1993A&AS..100...47G.
Giuricin, G.; Marinoni, C.; Ceriani, L.; Pisani, A. (2000). "Nearby Optical Galaxies: Selection of the Sample and Identification of Groups". Astrophysical Journal. 543 (1): 178–194. arXiv:astro-ph/0001140. Bibcode:2000ApJ...543..178G. doi:10.1086/317070. S2CID 9618325.
Ferrarese, L.; Ford, H. C.; Huchra, J.; Kennicutt Jr., R. C.; et al. (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 (2): 431–459. arXiv:astro-ph/9910501. Bibcode:2000ApJS..128..431F. doi:10.1086/313391.
47 out of 90 degrees north of the celestial equator. Thus its light emits as far south, to a good minimal cumulation of 15° above the horizon, once a day, on the 28th parallel south.
External links
Wikimedia Commons has media related to Whirlpool Galaxy.
StarDate: M51 Fact Sheet
M51: Calar Alto Observatory
SEDS: Spiral Galaxy M51
NASA Astronomy Picture of the Day: M51: The Whirlpool Galaxy in Dust and Stars (10 April 2001)
Whirlpool Galaxy at ESA/Hubble
The Whirlpool Galaxy (Messier 51(a)/NGC 5194)
M51 The Whirlpool Galaxy
The Whirlpool Galaxy at Constellation Guide
The Whirlpool Galaxy on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
Coordinates: Sky map 13h 29m 52.7s, +47° 11′ 43″
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Astronomical catalogs
Messier
M42 M43 M44 M45 M46 M47 M48 M49 M50 M51 M52 M53 M54 M55 M56 M57 M58 M59 M60
NGC
NGC 5189 NGC 5190 NGC 5191 NGC 5192 NGC 5193 NGC 5194 NGC 5195 NGC 5196 NGC 5197 NGC 5198 NGC 5199
PGC
PGC 47400 PGC 47401 PGC 47402 PGC 47403 PGC 47404 PGC 47405 PGC 47406 PGC 47407 PGC 47408
UGC
UGC 8489 UGC 8490 UGC 8491 UGC 8492 UGC 8493 UGC 8494 UGC 8495 UGC 8496 UGC 8497
Arp
Arp 79 Arp 80 Arp 81 Arp 82 Arp 83 Arp 84 Arp 85 Arp 86 Arp 87 Arp 88 Arp 89 Arp 90 Arp 91
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GC 3567 GC 3568 GC 3569 GC 3570 GC 3571 GC 3572 GC 3573 GC 3574 GC 3575 GC 3576 GC 3577
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List
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M104 M105 M106 M107 M108 M109 M110
Charles Messier.jpg
See also
Caldwell catalogue Catalogue of Nebulae and Clusters of Stars Herschel 400 Catalogue Index Catalogue New General Catalogue Revised New General Catalogue
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New General Catalogue 5000 to 5499
5000 5001 5002 5003 5004 5005 5006 5007 5008 5009 5010 5011 5012 5013 5014 5015 5016 5017 5018 5019 5020 5021 5022 5023 5024 5025 5026 5027 5028 5029 5030 5031 5032 5033 5034 5035 5036 5037 5038 5039 5040 5041 5042 5043 5044 5045 5046 5047 5048 5049 5050 5051 5052 5053 5054 5055 5056 5057 5058 5059 5060 5061 5062 5063 5064 5065 5066 5067 5068 5069 5070 5071 5072 5073 5074 5075 5076 5077 5078 5079 5080 5081 5082 5083 5084 5085 5086 5087 5088 5089 5090 5091 5092 5093 5094 5095 5096 5097 5098 5099 5100 5101 5102 5103 5104 5105 5106 5107 5108 5109 5110 5111 5112 5113 5114 5115 5116 5117 5118 5119 5120 5121 5122 5123 5124 5125 5126 5127 5128 5129 5130 5131 5132 5133 5134 5135 5136 5137 5138 5139 5140 5141 5142 5143 5144 5145 5146 5147 5148 5149 5150 5151 5152 5153 5154 5155 5156 5157 5158 5159 5160 5161 5162 5163 5164 5165 5166 5167 5168 5169 5170 5171 5172 5173 5174 5175 5176 5177 5178 5179 5180 5181 5182 5183 5184 5185 5186 5187 5188 5189 5190 5191 5192 5193 5194 5195 5196 5197 5198 5199 5200 5201 5202 5203 5204 5205 5206 5207 5208 5209 5210 5211 5212 5213 5214 5215 5216 5217 5218 5219 5220 5221 5222 5223 5224 5225 5226 5227 5228 5229 5230 5231 5232 5233 5234 5235 5236 5237 5238 5239 5240 5241 5242 5243 5244 5245 5246 5247 5248 5249 5250 5251 5252 5253 5254 5255 5256 5257 5258 5259 5260 5261 5262 5263 5264 5265 5266 5267 5268 5269 5270 5271 5272 5273 5274 5275 5276 5277 5278 5279 5280 5281 5282 5283 5284 5285 5286 5287 5288 5289 5290 5291 5292 5293 5294 5295 5296 5297 5298 5299 5300 5301 5302 5303 5304 5305 5306 5307 5308 5309 5310 5311 5312 5313 5314 5315 5316 5317 5318 5319 5320 5321 5322 5323 5324 5325 5326 5327 5328 5329 5330 5331 5332 5333 5334 5335 5336 5337 5338 5339 5340 5341 5342 5343 5344 5345 5346 5347 5348 5349 5350 5351 5352 5353 5354 5355 5356 5357 5358 5359 5360 5361 5362 5363 5364 5365 5366 5367 5368 5369 5370 5371 5372 5373 5374 5375 5376 5377 5378 5379 5380 5381 5382 5383 5384 5385 5386 5387 5388 5389 5390 5391 5392 5393 5394 5395 5396 5397 5398 5399 5400 5401 5402 5403 5404 5405 5406 5407 5408 5409 5410 5411 5412 5413 5414 5415 5416 5417 5418 5419 5420 5421 5422 5423 5424 5425 5426 5427 5428 5429 5430 5431 5432 5433 5434 5435 5436 5437 5438 5439 5440 5441 5442 5443 5444 5445 5446 5447 5448 5449 5450 5451 5452 5453 5454 5455 5456 5457 5458 5459 5460 5461 5462 5463 5464 5465 5466 5467 5468 5469 5470 5471 5472 5473 5474 5475 5476 5477 5478 5479 5480 5481 5482 5483 5484 5485 5486 5487 5488 5489 5490 5491 5492 5493 5494 5495 5496 5497 5498 5499
Astronomical catalog List of NGC objects
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List of notable Seyfert galaxies
Seyfert 1
Arakelian 120 Arakelian 564 Arp 102B 3C 59 ESO 141-055 ESO 198-G24 ESO 323-G077 ESO 362-18 Fairall 9 Fairall 51 H0557-385 1H 0419-577 1H 1707-495 IC 3599 IC 4329A IRAS 07598+6508 IRAS 13224-3809 IRAS 13349+1428 Markarian 6 Markarian 50 Markarian 79 Markarian 110 Markarian 279 Markarian 315 Markarian 334 Markarian 335 Markarian 359 Markarian 376 Markarian 423 Markarian 478 Markarian 507 Markarian 509 Markarian 609 Markarian 618 Markarian 704 Markarian 705 Markarian 817 Markarian 841 Markarian 896 Markarian 993 Markarian 1018 Markarian 1044 Markarian 1239 MCG -2-58-22 MCG-6-30-15 MGC +8-11-11 Messier 81 PG 1211+143 PG 1244+026 PG 1402+261 PG 1404+226 PKS 0558-504 PMN J0948+0022 RE J0134+396 SBS 0846+513 Ton S180 I Zw 1 III Zw 2 III Zw 77
Seyfert 2
Circinus Galaxy ESO 103-G35 ESO 428-G14 IC 2560 IC 3639 IRAS 05189-2524 IRAS 13197-1627 IRAS 18325-5926 IRAS 19014+4109 IRAS F01475-0740 Markarian 3 Markarian 34 Markarian 78 Markarian 176 Markarian 266 SW Markarian 273 Markarian 463 Markarian 477 Markarian 573 Markarian 1066 Markarian 1210 MCG-5-23-16 Messier 77 Messier 88 Messier 106 NGC 454E NGC 2788A NGC 4676B NGC 4922N Whirlpool Galaxy
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Constellation of Canes Venatici
Giant Void List of stars in Canes Venatici Canes Venatici in Chinese astronomy
Stars
Bayer
α (Cor Caroli) β (Chara)
Flamsteed
4 5 6 10 19 20 21 24 25
Variable
R Y (La Superba) AM AW BH DG RS
HR
4997
Other
Gliese 521 HAT-P-12 Tuiren
Exoplanets
Bran HAT-P-12b
Star clusters
Messier 3
Galaxies
Messier
51 (Whirlpool Galaxy) 63 94 106
NGC
4111 4138 4145 4151 4163 4183 4214 4217 4242 4244 4395 4399 4400 4401 4449 4485 4490 4534 4618 4625 4627 4631 4656 4657 4707 4800 4861 5002 5003 5005 5023 5033 5112 5195 5223 5229 5238 5371
Other
B2 1225+317 3C 285 3C 286 3C 288 Canes Venatici I Canes Venatici II DDO 169 IC 883 I Zwicky 36 KKR 03
Galaxy clusters
Canes II Group M51 Group M94 Group NGC 4631 Group
Astronomical events
GRB 090429B SN 1994I SN 2005cs SN 2008ax
Category Category
Hellenica World - Scientific Library
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