{"id":4340,"date":"2016-08-14T16:50:35","date_gmt":"2016-08-14T15:50:35","guid":{"rendered":"http:\/\/outters.fr\/?p=4340"},"modified":"2025-07-15T17:04:12","modified_gmt":"2025-07-15T16:04:12","slug":"m81","status":"publish","type":"post","link":"https:\/\/www.outters.fr\/?p=4340","title":{"rendered":"m81"},"content":{"rendered":"

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m81<\/strong>
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\"m81\"<\/a><\/span><\/div><\/div><\/div>
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Commentaires sur l’objet photographi\u00e9<\/span><\/p><\/h1><\/span>

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\"outters-nicolas\"Voici une image qui me plait bien, elle r\u00e9sulte de 2 ann\u00e9es d’efforts \u00e0 Castor-Sirene et le r\u00e9sultat est \u00e0 la hauteur du travail entrepris.
\nIl existe encore quelques reflets bizarres que je ne m’explique pas encore mais \u00e7a commence \u00e0 me plaire.<\/p>\n<\/div>

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Image LRGB<\/h2><\/a><\/div><\/div><\/div>
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Donn\u00e9es techniques
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Donn\u00e9es techniques de prise de vue<\/h2><\/div>
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Object :M81
\nDate : du 18 janvier au 18 fevrier 2012
\nOptics :Rcos 12″
\nMount : Paramount ME Num\u00e9ro 3
\nLocation : Castor Sirene observatory
\nSeeing : FWHM de 1,7 \u00e0 2,5 arc sec(ccdinspector)
\nCcd : Apogee 16803
\nfilter wheel :Apogee
\nfilters : Astrodon LRGB
\nFocuser :TCC Rcos
\nGuiding : MMOAG Astrodon et Atik 314L+
\nTemp. out : -5 \u00b0\u00e0 5\u00b0
\nTemp ccd : -25\u00b0
\nTotal exposure :17 h 50
\nLuminance 69 x 10mn bining 1×1
\nRouge 13 x 10 mn bining 1×1
\nVert 11 x 10 mn bining 1×1
\nBleu 12 x 10 mn bining 1×1<\/div><\/div><\/div>
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Donn\u00e9es scientifiques<\/h2><\/div>
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M81 est une galaxie spirale<\/a> d’un diam\u00e8tre relativement modeste de 60\u00a0000\u00a0ann\u00e9es-lumi\u00e8re<\/a><\/span>. En 1993<\/a>, l’observation d’une trentaine de c\u00e9ph\u00e9ides<\/a> par le t\u00e9lescope Hubble<\/a> a permis d’estimer la distance de la galaxie \u00e0 11,8\u00a0millions d’ann\u00e9es-lumi\u00e8re<\/span>, ce qui en fait l’une des plus proches de la n\u00f4tre<\/a>. Elle fait partie du m\u00eame groupe de galaxies<\/a> que M82<\/a>, le groupe de M81<\/a> (le groupe G2 de la liste de Vaucouleurs<\/a>). Ce groupe fait partie du superamas de la Vierge<\/a>, de m\u00eame que notre groupe local<\/a>.<\/p>\n

La r\u00e9partition de la masse<\/a> de la galaxie n’est pas homog\u00e8ne en raison de l’effet de mar\u00e9e d\u00fb \u00e0 la proximit\u00e9 (~150\u00a0000\u00a0al<\/a><\/span>) d’une autre galaxie moins massive. Le noyau de la galaxie abriterait un trou noir<\/a> de 60 millions\u00a0M\u2299<\/sub><\/a><\/span>.<\/p>\n

Une seule supernova<\/a> a \u00e9t\u00e9 observ\u00e9e dans cette galaxie1<\/a><\/sup>, SN 1993J, d\u00e9couverte le 28<\/a> mars<\/a> 1993<\/a><\/time> par l’astronome amateur F. Garcia en Espagne2<\/a><\/sup>. Les caract\u00e9ristiques spectrales<\/a> de cette supernova ont \u00e9volu\u00e9 avec le temps. Initialement de type II, avec une raie de l’hydrog\u00e8ne<\/a> marqu\u00e9e, elle \u00e9volua vers un type Ib, et la raie de l’hydrog\u00e8ne s’estompa au profit de la raie de l’h\u00e9lium<\/a>3<\/a><\/sup>,<\/sup>4<\/a><\/sup>. De plus, les variations temporelles de luminosit\u00e9 de SN 1993J n’\u00e9taient pas semblables \u00e0 celles des autres supernovas de type II5<\/a><\/sup>,<\/sup>6<\/a><\/sup>, mais plut\u00f4t \u00e0 celles observ\u00e9es pour les types Ib7<\/a><\/sup>. La supernova a donc \u00e9t\u00e9 class\u00e9e de type IIb, une classe transitoire entre les types II et Ib4<\/a><\/sup>. Les r\u00e9sultats scientifiques tir\u00e9s de l’\u00e9tude de cette supernova sugg\u00e8rent que les supernovas de types Ib et Ic se forment lors d’explosions d’\u00e9toiles superg\u00e9antes<\/a>, \u00e0 travers un processus \u00e9quivalent \u00e0 celui des supernovas de type II4<\/a><\/sup>,<\/sup>8<\/a><\/sup>.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Donn\u00e9es d\u2019observation
\n(\u00c9poque<\/a> J2000.0<\/a>)<\/small><\/th>\n<\/tr>\n
Constellation<\/a><\/th>\nGrande Ourse<\/a><\/td>\n<\/tr>\n
Ascension droite<\/a> (\u03b1)<\/th>\n09h<\/sup>\u00a055m<\/sup>\u00a033,173s<\/sup><\/td>\n<\/tr>\n
D\u00e9clinaison<\/a> (\u03b4)<\/th>\n+69\u00b0\u00a003\u2032\u00a055,061\u2033<\/td>\n<\/tr>\n
Distance<\/th>\n11\u00a08 \u00b1 1\u00a01 million\u00a0al<\/a><\/span>
\n(3\u00a06 \u00b1 0\u00a03 millions\u00a0pc<\/a><\/span>)<\/td>\n<\/tr>\n
Magnitude apparente<\/a> (V)<\/small><\/th>\n6,9<\/td>\n<\/tr>\n
Dimensions apparentes (V)<\/small><\/th>\n26,9′ \u00d7 14,1′<\/td>\n<\/tr>\n
Caract\u00e9ristiques physiques<\/th>\n<\/tr>\n
Type d’objet<\/th>\ngalaxie spirale<\/a> (SA(s)ab)<\/td>\n<\/tr>\n
Masse<\/a><\/th>\n?\u00a0M\u2609<\/sub><\/a><\/td>\n<\/tr>\n
Dimensions<\/th>\n60000
\n(18000\u00a0pc<\/a>)<\/td>\n<\/tr>\n
Magnitude absolue<\/a><\/th>\n21,1<\/td>\n<\/tr>\n
Couleur (B-V)<\/small><\/th>\n?<\/td>\n<\/tr>\n
D\u00e9couverte<\/th>\n<\/tr>\n
D\u00e9couvreur(s)<\/th>\nJohann Elert Bode<\/a><\/td>\n<\/tr>\n
Date<\/th>\n1774<\/a><\/td>\n<\/tr>\n
D\u00e9signation(s)<\/th>\nM<\/a>81, NGC<\/a> 3031, UGC<\/a> 5318, PGC<\/a> 28630<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div><\/div><\/div>
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