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Pinwheel Galaxy - Wikipedia, the Free Encyclopedia Pinwheel Galaxy Coordinates: 14H 03M 12.6S, +54° 20′ 57″ from Wikipedia, the Free Encyclopedia 9/25/2014 Pinwheel Galaxy - Wikipedia, the free encyclopedia Pinwheel Galaxy Coordinates: 14h 03m 12.6s, +54° 20′ 57″ From Wikipedia, the free encyclopedia The Pinwheel Galaxy (also known as Messier 101, M101 or NGC 5457) is a face-on spiral galaxy distanced 21 million light-years (six megaparsecs)[2] away in the constellation Ursa Major, first Pinwheel Galaxy discovered by Pierre Méchain on March 27, 1781, and communicated to Charles Messier who verified its position for inclusion in the Messier Catalogue as one of its final entries. On February 28, 2006, NASA and the ESA released a very detailed image of the Pinwheel Galaxy, which was the largest and most detailed image of a galaxy by Hubble Space Telescope at the time.[7] The image was composed from 51 individual exposures, plus some extra ground-based photos. On August 24, 2011, a Type Ia supernova, SN 2011fe, was discovered in M101. Contents 1 Discovery Observation data (J2000 epoch) 2 Structure and composition Constellation Ursa Major 3 Companion galaxies Right ascension 14h 03m 12.6s 4 Supernova Declination +54° 20′ 57″ 5 See also Redshift 0.000804 6 References Helio radial velocity 241 ± 2 km/s 7 External links Distance 20.9 ± 1.8 Mly (6.4 ± 0.5 Mpc) Type SAB(rs)cd Discovery Apparent 28′.8 × 26′.9 dimensions (V) Apparent 7.86 http://en.wikipedia.org/wiki/Pinwheel_Galaxy 1/7 9/25/2014 Pinwheel Galaxy - Wikipedia, the free encyclopedia Pierre Méchain, the discoverer of Messier 101, described it as a "nebula without star, very obscure magnitude (V) and pretty large, 6' to 7' in diameter, between the left hand of Bootes and the tail of the great Bear. It Other designations is difficult to distinguish when one lits the [grating] wires."[8] Messier 101, M101, NGC 5457, UGC 8981, PGC William Herschel noted in 1784 that "[M101] in my 7, 10, and 50063, Arp 26 20-feet [focal length] reflectors shewed a mottled kind of nebulosity, which I shall call resolvable; so that I expect my References: [1][2][3][4][5][6] present telescope will, perhaps, render the stars visible of which I See also: Galaxy, List of galaxies suppose them to be composed."[8] The Pinwheel Galaxy Lord Rosse observed M101 in his 72-inch diameter Newtonian reflector during the second half of the 19th century. He was the first to make extensive note of the spiral structure and made several sketches.[8] To observe the spiral structure in modern instruments requires a fairly large instrument, very dark skies, and a low power eye piece. Structure and composition M101 is a relatively large galaxy compared to the Milky Way. With a diameter of 170,000 light-years it is seventy percent larger than the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses.[9] M101 is noted for its high population of H II regions, many of which are very large and bright. H II regions usually accompany the enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force where stars form. H II regions are ionized by large numbers of extremely bright and hot young stars; those in M101 are capable of creating hot superbubbles.[10] In a 1990 study, 1264 H II regions were [11] cataloged in the galaxy. Three are prominent enough to receive New General Catalogue numbers - NGC Combined infrared, visible, and x-ray 5461, NGC 5462, and NGC 5471.[12] images of M101 showing that both young and old stars are evenly M101 is a asymmetrical due to the tidal forces from interactions with its companion galaxies. These gravitational distributed along the tightly-wound interactions compress interstellar hydrogen gas, which then triggers strong star formation activity in M101's spiral arms. spiral arms that can be detected in ultraviolet images.[13] http://en.wikipedia.org/wiki/Pinwheel_Galaxy 2/7 9/25/2014 Pinwheel Galaxy - Wikipedia, the free encyclopedia In 2001, the x-ray source P98, located in M101, was identified as an ultra-luminous X-ray source - a source more powerful than any single star but less powerful than a whole galaxy - using the Chandra X-ray Observatory. It received the designation M101 ULX-1. In 2005, Hubble and XMM-Newton observations showed the presence of an optical counterpart, strongly indicating that M101 ULX-1 is an x-ray binary.[14] Further observations showed that the system deviated from expected models - the black hole is just 20 to 30 solar masses, and consumes material (including captured stellar wind) at a higher rate than theory suggests.[15] Companion galaxies M101 has five prominent companion galaxies: NGC 5204, NGC 5474, NGC 5477, NGC 5585, and Holmberg IV.[16] As stated above, the gravitational interaction between M101 and its satellites may have triggered the formation of the grand design pattern in M101. M101 has also probably distorted the companion galaxy NGC 5474.[16] M101 and its companion galaxies comprise most or possibly all of the M101 Group.[17][18][19][20] Supernova On August 24, 2011, a Type Ia supernova, SN 2011fe, initially designated PTF 11kly, was discovered in M101. The supernova was visual magnitude 17.2 at discovery and reached magnitude 9.9 at its peak.[21][22][23] This was the fourth supernova recorded in M101. The first, SN 1909A, was discovered by Max Wolf in January 1909 and reached magnitude 12.1. SN 1951H reached magnitude 17.5 in September 1951 and SN 1970G reached magnitude 11.5 in January 1970.[24] Type Ia supernova SN 2011fe See also Messier 74 – a similar face-on spiral galaxy Messier 83 – a similar face-on spiral galaxy that is sometimes called the Southern Pinwheel Galaxy Messier 99 – a similar face-on spiral galaxy http://en.wikipedia.org/wiki/Pinwheel_Galaxy 3/7 9/25/2014 Pinwheel Galaxy - Wikipedia, the free encyclopedia Triangulum Galaxy – another galaxy sometimes called the Pinwheel Galaxy References 1. ^ "NASA/IPAC Extragalactic Database" (http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=Messier+101&img_stamp=yes&extend=no). Results for Messier 101. Retrieved 2006-12-06. 2. ^ a b Shappee, Benjamin; Stanek, Kris (June 2011). "A New Cepheid Distance to the Giant Spiral M101 Based on Image Subtraction of Hubble Space Telescope/Advanced Camera for Surveys Observations". Astrophysical Journal 733 (2): 124. arXiv:1012.3747 (https://arxiv.org/abs/1012.3747). Bibcode:2011ApJ...733..124S (http://adsabs.harvard.edu/abs/2011ApJ...733..124S). doi:10.1088/0004-637X/733/2/124 (http://dx.doi.org/10.1088%2F0004- 637X%2F733%2F2%2F124). 3. ^ R. W. Sinnott, ed. (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Corporation / Cambridge University Press. ISBN 0-933346-51-4. 4. ^ "Distance Results for Messier 101" (http://nedwww.ipac.caltech.edu/cgi-bin/nDistance?name=MESSIER+101). NASA/IPAC Extragalactic Database. Retrieved 2010-05-01. 5. ^ "SIMBAD-M101" (http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M101). SIMBAD Astronomical Database. Retrieved 2009-11-29. 6. ^ Armando, Gil de Paz; Boissier; Madore; Seibert; Boselli; et al. (2007). "The GALEX Ultraviolet Atlas of Nearby Galaxies". Astrophysical Journal Supplement 173 (2): 185–255. arXiv:astro-ph/0606440 (https://arxiv.org/abs/astro-ph/0606440). Bibcode:2007ApJS..173..185G (http://adsabs.harvard.edu/abs/2007ApJS..173..185G). doi:10.1086/516636 (http://dx.doi.org/10.1086%2F516636). 7. ^ HubbleSite – NewsCenter – Hubble's Largest Galaxy Portrait Offers a New High-Definition View (02/28/2006) – Introduction (http://hubblesite.org/newscenter/newsdesk/archive/releases/2006/10/) 8. ^ a b c SEDS Historical Notes (http://messier.seds.org/Mdes/dm101.html) 9. ^ Comte, G., Monnet, G., & Rosado, M.; Monnet; Rosado (1979). "An optical study of the galaxy M 101 - Derivation of a mass model from the kinematic of the gas". Astronomy and Astrophysics 72: 73–81. Bibcode:1979A&A....72...73C (http://adsabs.harvard.edu/abs/1979A&A....72...73C). 10. ^ Immler, Stefan and Wang, Q. Daniel (2001). "ROSAT X-Ray Observations of the Spiral Galaxy M81" (http://iopscience.iop.org/0004-637X/554/1/202/). The Astrophysical Journal 554 (1): 202. arXiv:astro-ph/0102021 (https://arxiv.org/abs/astro-ph/0102021). Bibcode:2001ApJ...554..202I (http://adsabs.harvard.edu/abs/2001ApJ...554..202I). doi:10.1086/321335 (http://dx.doi.org/10.1086%2F321335). Retrieved 12 May 2014. 11. ^ Hodge, Paul W. et al; Gurwell, Mark; Goldader, Jeffrey D.; Kennicutt, Robert C., Jr. (August 1990). "The H II regions of M101. I - an atlas of 1264 emission regions". Astrophysical Journal Supplement Series 73: 661–670. Bibcode:1990ApJS...73..661H (http://adsabs.harvard.edu/abs/1990ApJS...73..661H). doi:10.1086/191483 (http://dx.doi.org/10.1086%2F191483). http://en.wikipedia.org/wiki/Pinwheel_Galaxy 4/7 9/25/2014 Pinwheel Galaxy - Wikipedia, the free encyclopedia 12. ^ Giannakopoulou-Creighton, J.; Fich, M.; Wilson, C. D. (1999). "Star formation in the giant HII regions of M101". The Astrophysical Journal 522: 238. arXiv:astro-ph/9903334 (https://arxiv.org/abs/astro-ph/9903334). Bibcode:1999ApJ...522..238G (http://adsabs.harvard.edu/abs/1999ApJ...522..238G). doi:10.1086/307619 (http://dx.doi.org/10.1086%2F307619). 13. ^ Waller, William H. et al; Bohlin, Ralph C.; Cornett, Robert H.; Fanelli, Michael N.; Freedman, Wendy L.; Hill, Jesse K.; Madore, Barry F.; Neff, Susan G.; Offenberg, Joel D.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P. (20 May 1997). "Ultraviolet Signatures of Tidal Interaction in the Giant Spiral Galaxy M101" (http://iopscience.iop.org/0004-637X/481/1/169).
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