Revista Mexicana de Astronomía y Astrofísica ISSN: 0185-1101 [email protected] Instituto de Astronomía México

Rozas, M. A dynamical model for the spiral ngc 3359 Revista Mexicana de Astronomía y Astrofísica, vol. 44, núm. 1, abril, 2008, p. 7183 Instituto de Astronomía Distrito Federal, México

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How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México ntegsoscmoeto h ytmadprovoke perturbation and spiral system the a of produce component gaseous can the bar provein through to weak possible a addition, been that In has it simulations, waves. re- numerical mechanisms density possible the for of sponsible have one Bars be to component. shown bar a been demon- or existence component have the oval systems, an images disc of of infrared majority the as in strated, decades few past eit eiaad Astronom´ de Mexicana Revista neeti ardglxe a nrae nthe in increased has barred in Interest YAIA OE O H PRLGLX G 3359 NGC GALAXY SPIRAL THE FOR MODEL DYNAMICAL A num´ prl eope rmtencerrgo,wihrttswt nua eoiy Ω velocity, angular a with rotates which region, nuclear the from decoupled spiral, w atr pe oe:tecnrlrgo u o15 to (up region for obtained central are the the results for best model: responsible The speed parameters de- gas. the pattern potential observed find two the to the consistent a attempt of using self we morphology and present image, and we 3359; band kinematics work NGC I see this in an can In from gas we rived molecular which formation. of within simulations structure, intense complex numerical of a zone with annular galaxy an spiral barred strongly a =27kms hsa15 (hasta par´ los encontramos I, banda cinem´ la la en imagen una de derivado sae n aai sia ureet ard srcuamnecmlj,in- compleja, formaci´ estructuralmente fuerte y con barrada anular fuertemente zona espiral una cluyendo galaxia una es Esta patr´ el namos e Words: Key uniquemodepattern. ula,qert o n eoia nua,Ω angular, velocidad una con rota que nuclear, H uln ud e xlcd o n´ un con explicada ser puede no cual erdc inl opeaetutr nH en estructura compleja la bien reproduce kpc beiocnu oeocndsptoe evlcdddfrne:l regi´ la diferentes: velocidad de patrones dos con modelo un con obtenido ula a hc oae ihaΩ a with rotates which bar nuclear ´ .INTRODUCTION 1. α − fteglx nteitra 20 internal the in galaxy the of rcsat-ossetsdlgsmlclrd G 39 snoe potencial el usando y 3359, NGC de molecular gas del auto-consistentes ericas 1 net rbj,cnsmlcoe num´ simulaciones con trabajo, este En nti okw aedtrie yaia oe o G 39 hsis This 3359. NGC for model dynamical a determined have we work this In abrapicpl ut o aeprletra eaoldsd aregi´ la de desacopladas externa, espiral la con junto principal, barra la y ; nvria ainlAut´ Nacional Universidad tc el morfolog´ la de y atica − u orsod abrancerrt o n Ω una con rota nuclear barra la a corresponde que ) 1 aais niiul(G 39 aais ieaisaddynamics and kinematics galaxies: — 3359) (NGC individual galaxies: aais spiral galaxies: — nd eoia osrio nmdl din´ modelo un construimos y velocidad de on kpc eevd20 ue1;acpe 07Nvme 8 November 2007 accepted 12; June 2007 Received ayAstrof´ y ıa − 1 h oe ucsflyrpoue h ope tutr in structure complex the reproduces successfully model The . ısica nttt eAstronom´ de Instituto adlgsosrao o eoe eutdss han se resultados mejores Los observado. gas del ıa nm eM´ de onoma , 44 s ABSTRACT RESUMEN 10k s km =100 nc patr´ unico 18 (2008) 71–83 , .Rozas M. oe hc antral eepandwt a with explained be really cannot which zone, eodr ncer as yial xedoe less the over kpc. and 1 extend galac- than typically kpcs, the bars, several (nuclear) define over secondary which al. extend bars, et morphology, primary Kenney Maiolino tic 1995; The 1999; 2000; Sparke Sparke 2000). & al. & Erwin et Maciejewski 1996; Shaw 1998; (e.g., al. et bars Friedli double show which Gerin & Combes moment 1985). 1976; angular Huntley & the (Sanders transfer outward which torques strong α rcsdlmdoitrsea,determi- interestelar, medio del ericas xc,Esnd,B . Mexico C., B. Ensenada, exico, netlr rsnao simulaciones Presentamos estelar. on nd velocidad. de on − el aai nl oaitra la interna, zona la en galaxia la de p 1 hr sasbtnilnme fds galaxies disk of number substantial a is There =27kms kpc ıa − 1 n h anbr+outer + bar main the and ; mto epnalsde responsables ametros − mc aaNC3359. NGC para amico orsodn othe to corresponding ) 1 kpc s − 1 0 ms km 100 = semodelo Este . ncentral on on − p 1 71 © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México 2ROZAS 72 h icado h cl egho h ic(Combes disc the of length and scale bulge the the on of and masses the disc of of the ratio the speed on pattern depends the bars that indicate which lations galaxies of properties. types dynamic different different the have in types. should bars early the to case late this from In evolve galaxies the sequence, which dynamic under a in sequence, be Hubble also can the circumstances, and these time a speed with essentially pattern vary the is then will bar mass, the accreted of the evolution of the resonances function principal If the disc. of the speed position in pattern the the to to and bar related of directly process is evolutionary system global the the of in role true their and face-on a in dynamically arbitrary. them is are between disk bars angle both the case, and this decoupled (Shlos- occur In to this 1999). for of man imperative presence be The to chaotic appears of 1990). gas Norman fraction & the (Pfenniger (ILR) reducing orbits resonance bar, Lindblad primary inner the the of equal of approximately radius being the bar to nuclear bar. the be corotation of the primary will to radius the corresponds bar arrangement of nuclear this best that The the In than of 1989). higher speed substantially al. pattern the et the by (Shlosman direction case, bar given the primary in direction i.e., the the disk, of the gaseous in in momentum spin or angular must stellar it the disks), (in instability gravitational Frank & Begelman, Shlosman, 1990). 1989; Begelman Frank, (Shlosman, & starbursts ac- and in nuclei mechanism bars galactic fueling tive gas nested a with as proposed scenarios been & have These Friedli by was (1993). coexist, simulations Martinet zone can numerical bars central through within the bars shown in where galaxy, speeds a pattern of different existence the two of of possibility This behav- the to galaxies. the opens appropriate which early-type case more scenario, of this appears kinematics the it In describe and transient galaxy. is the ior during in coexist waves time can two some speeds curve) (a pattern rotation different high two very the with is in concentration peak mass struc- pronounced the simulations spiral if numerical that the multiple show as Nevertheless, speed pattern ture. same itself the bar shares A defined standing bar. well a a a by is through driven wave general predominant in and explained be can hr r tde ihNbd ueia simu- numerical N-body with studies are There evolve and formed are bars how of problem The self- via formed is bar nuclear a if Theoretically, galaxies isolated design grand in patterns The m 2wv oe hti h models the in that mode, wave =2 r on ob oeloeydsrbtdaon the around distributed loosely more be to found are that Nev- appears it 1995). galaxies, thenumberofHIIregionsismuchlowerandthey (Martin type axis early mayor within ertheless, the formation the stellar along high a rate have spirals late-type in bars re- 1995). Filippenko, internal Sargent Ho, the & 1995; in Martin 1994; the (Kennicutt generate massive gions and more nucleus of the formation around formation lar does clearly but rate, af- formation not star does bar global the the of presence fect the that appears, stage, It this at resonance). Lindblad inner extended and inter- The and bars evolution. modify stellar between dynamical can coupling gravitational galaxy’s bars the the that influence 1993; shown and or have Benz, formation These & stellar (Friedli 1995). separately gas, cooling stars, galax- radiative consider barred isolated that of evolution ies the of made been es- limited be would bar corotation. by the sentially which in early- the to galaxies contrary of type resonances, length the scale by than the rather by disc type limited late be in should bars the galaxies Therefore, 1993). Elmegreen, & prlo rn ein sltd ihavr strong very barred a a with is isolated, it design, grand galaxies: of barred spiral for predictions ical nucleus. stel- of ap- rate higher it a show Therefore, galaxies barred that region. pears circumnuclear the affect strong produc- a of nucleus (appearance the bar the to of destruction gas the fuel ing can medium stellar h anrsnne nteds.In disc. the of in position resonances the main of for- the star determination of the morphology through the mation and dynamics global the disc. the along distributed also and H complex a and bar theoret- the and observations the between parisons eieadsac f1. p.Iscmlxmorphol- complex Its Mpc. 13.4 of distance a derive lrsa omto ein ocnrtdi h bar the in concentrated regions formation star ular ecito fNC35,in 3359, NHC of description acuer ta.(91.Fo t ailvelocity radial s its From km de 1008 (1991). by of SBc(rs) al. as or et Vaucouleurs (1981) Tammann & Sandage by togbr(e iue1,casfida B()1.8 SBc(s) as classified 1), Figure (see bar strong a observations galaxy the H of in comparison a from found in finally and model merical eetbre aaysresidct htyoung that indicate surveys galaxy barred Recent have 3D in simulations numerical Self-consistent nti ae ehv on oncinbetween connection a found have we paper this In com- perform to candidate good a is 3359 NGC G 39i rn-einsia aaywith galaxy spiral grand-design a is 3359 NGC α .NC35;GOA PROPERTIES GLOBAL 3359; NGC 2. n Iadnmrclsimulations. numerical and HI and − 1 ,usingH α tutr,wt ayspectac- many with structure, 0 =75kms § § edsusteresults the discuss we 4 epeettenu- the present we 3 § − epeeta present we 2 1 Mpc − 1 ,we © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México Fgrs2 n b r lal eni h I-band the in seen clearly are bar 3b) nuclear and misaligned 2b apparently (Figures an and strong bar A main features. different prominent at taken showing images wavelengths, analyze we if out stands ogy i.1 rysaerpeetto ftecniumsbrce H continuum-subtracted the of representation scale Grey 1. Fig. YAIA OE O H PRLGLX G 3973 3359 NGC GALAXY SPIRAL THE FOR MODEL DYNAMICAL anbr nelnn h bec fsa formation star nucleus. of the absence in the underlining the bar, with main misaligned maxima prominent two presents mg.TeH The image. α α itiuini h ne 20 inner the in distribution mg o G 3359. NGC for image region © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México i.2 a vra fH of potential. Overlay (a) 2. Fig. ROZAS 74 α eas h - mg hw otceryaspiral a clearly most shows dust, image we by I-K divided 2000a) the them, compose because al. the which and et spots” formation star (Rozas “hot of segments map elongated see this can In formation. igradbte endta h atr r.The H arm. tha eastern of the that slope defined better brighter, and much are bigger being arms arm the western the of intensities disparate, regions very The fainter many arms. spiral are the within there along the concentrated and bar, zone, are the annular regions of an HII Outside the end. of its majority bursts at strong formation and of star length chain of its H a along see total regions can the we HII which bright dominates in galaxy, bar the The of endowed emission well regions. arms, defined HII well has with it see, can we As H using stud- undertaken been detailed have most galaxy and The this and (1987) of Chaude ies (1992). (1981), & Combes Elmegreen Elmegreen, & by Stark, Braine IR by CO near in the in (1969), o aaiso iia type: previously similar found values of of galaxies range for the within is gions nFgr eso rysaerpeetto of representation scale grey a galaxy. show H the we the of 1 kinematics global Figure the In prop- HII as physical well the other as of and erties distribution luminosities the their al. regions, analyze et Rozas They and (2000a) (2000b). Beckman & Zurita, Rozas, = G 39wsfis bevdi H in observed first was 3359 NGC h - a enstedtie oain fstar of locations detailed the defines map U-I The − α 1 . 69 otnu-utatdiaeo G 3359. NGC of image continuum-subtracted ± 0 . α 06. uioiyfnto fteHIre- HII the of function luminosity α n Iiae sdfrfitn h oe.()Ibn mg rmwihw aedrvdthe derived have we which from image I-band (b) model. the fitting for used images HI and dNL = AL α yHodge by α dL α with by α rud1%o h oa H total the of 17% Around eietdb h togds ae unn along running lanes dust arms. strong the the by delineated a 18)adb al(96,wt eouin of resolutions with (1986), Ball 42 by Gottes- by and detail (1982) in man analyzed were hydrogen atomic a eepanda u osa omto ntegas case the this in in formation star spots to hot due The as explained stage. be (1994) which formative can bar Kennicutt a a along at & predictable Benz is are Benz, & gas Friedli of Friedli, flows to strong to According and bar. (1993) the from comes to corresponds (which arcmin 2.9 of length the of structure component oval spiral an outer pattern galaxy. add extended one the to a obtain had used to he he and model, this model In speed quickly too radii. off large falls stellar obtained at thus the force of the since photometry bar, surface the potential from non-axisymmetric obtained not the could from bar, structure reproduced the spiral in the be that density kinematics concluded stellar gas he the and the on based ro- reproducing models it galaxy, with as the anal- gas hydrodynamical of up a ysis sweeps by produced which (1992) explained Ball bar, be tates. the of can of zone effect which annular the formation, the star within and density strong clumps, surface in these HI low of the the of results distribution significant the were most works The respectively. h tutr n ieaiso h neutral the of kinematics and structure The h a fNC35 a erjce total deprojected a has 3359 NGC of bar The × 31 n 45k s km 24.5 and − 1 ,and18 α u rmtegalaxy the from flux n 5k s km 25 and ∼ 9kpc). − 1 © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México h de ftencerbr h L fteso oe(Ro h atpten dpe ntenmrclsimulations numerical the in adopted pattern) fast the of (CR mode slow the of ellipse. ILR an The as bar. displayed nuclear is the of edges the infistegnrlseai fabri h process the in bar a forma- of star formation. scenario strong of general of the region fits bar with tion the together in This, presence bar. in the flowing the gas around as orbits region explains elliptical this (2000b) in al. gradients et velocity Rozas the mo- & in circular bar non Beckman, the the around non- of Rozas, tions analysis with in The compared (1998). reported Knapen spirals as barred symmetry spirals, formation of barred star mixing arms reduced of the the type in this is of disc effect the related in in- for- A star the differential rate. out radially mation a smooth has to to there due turbulence gradient that in trinsic for so that time forming, fact still been the is not to bar the effect 3359 the this NGC within attributed gradient Mar- They higher however, a 3359, bar. found (1995) NGC Roy In & tin discs. those external than lower the much are in galaxies barred within of gradients bars the the that showed (1992) Costas Edmunds Vila & galaxies, in general gradients metallicity a of In study gradients. metallicity their include tures spots. hot the stars reso- hence massive inner and producing the galaxy, in the of trapped structure bar be nant general can more gas the This in and potential. shocks the momentum in angular absorbed shocks, its is interstellar as centre to the due towards bar, falls the but forma- of star ends intense the at the tion to contributed not has which i.3 a omo h -adiaet hwtetodculdbr:tomn prllaigam s)sata the at start (s1) arms leading spiral H mini central two the on bars: superposed decoupled I-bar two the the of show Contours to (b) image bar. I-band nuclear the the of of Zoom edges (a) 3. Fig. rpriso asrltdt hi eoiystruc- velocity their to related bars of Properties YAIA OE O H PRLGLX G 3975 3359 NGC GALAXY SPIRAL THE FOR MODEL DYNAMICAL al 1. Table in a efudi oa ta.(2000a,b). al. et Rozas observa- in the found of be can description tions detailed numerical our A Observatory of results Muchachos simulations. the los with tele- compare de Herschel to Roque (Spain) William m the 4.2 at the scope with (2000a) al. paper et this H In the use data. will resolution we high from (2000b), al. are u yBl 18) hscreare well agrees H curve in curve This rotation (1986). the Ball with by out carried h lblpoete fteglx r e u in out set are galaxy the of properties global The h rtdtriaino oaincrewas curve rotation a of determination first The G 39 AI PARAMETERS BASIC 3359: NGC ..170 P.A. log B e 20)63 (2000) Dec (p)13.4 .SBT5.. d log D(Mpc) Type 10 (2000) R.A. v opt T r 25 25 α α ein oetetoH two the Note region. n -adiaetknb Rozas by taken image I-band and AL 1 TABLE 08k s km 1008 α h ◦ 46 11.03 eie yRzset Rozas by derived 0.22 1.86 13 m 37 22 − s .7 1 α aiaat maxima © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México clsmltoso h yaia eairo the of behavior namely: dynamical medium, the interstellar molecular of simulations ical also have runs. spiral we some the Therefore, in self-gravity of included considered. order are the width of arm distances scale impor- the be when of can center tant included the is to self-gravity relative when shock potential gas the Nevertheless, of negligible. shift is the contribu- potential its total and the galaxy, to this than tion in distri- less mass total gas for the accounts the of 10% not component of is this fit gas since scale the bution, large in the self-gravity for of determinant potential. lack have we the 1994) imposed that al. the shown et (Sempere in paper previous particles a From mainly test con- are are as clouds simulations sidered molecular bar Our its and of non-self-gravitating, structure. responsible pa- spiral wave important most density and the the derive of to rameters and observations 3359 fit to NGC out in carried been have component iuain r h atr pe ftebr+spiral + bar the Ω of perturbation, speed pattern the are simulations spatial radii. higher a these provides at galaxy which resolution grid the polar of model a anal- center numerical on based sophisticated detailed the more A in a behavior require 1993). would gas Combes the al. 1980; of et Tubbs ysis Shaw & bar 1985; a (Sanders gas Gerin of a bar & region between stellar shift inner a a the and produce in can ILRs galaxy Neverthe- of spiral component. existence spiral the the and less, bar potential the the of to perturbation due spi- the isolated follows in galaxies gas ral molecular of indicate distribution observations the the that since the potential, and disc gas stellar molecular the between fit morphological o oaincre.Teacrc ftemto is method the of accuracy The curve). rotation (or 95;NC17(epr oa 1997). Casoli Rozas & & Combes, (Sempere (Sempere, 157 et NGC 7479 Sempere 1995); NGC and 1994); (Garc´ 1994, Combes al. 51 & (Garc´ 4321 M Sempere, NGC Burillo, 1993); Gerin galaxies: & Combes, grand-design Burillo, speed pattern several the of in determination the for used been 6ROZAS 76 • • h w aniptprmtr ftenumerical the of parameters input main two The global best the find to designed are models The ehv efre w ieetrn fnumer- of runs different two performed have We disc gas molecular the of simulations Numerical h ueia oesapidt G 39have 3359 NGC to applied models numerical The sn h oe fcodieatccliin pro- collisions inelastic cloud of model the using sn oicto ftepeiu oe in- model previous the of modification a using ldn egssl-rvtto n atal in- partially collisions. and elastic self-gravitation gas de cluding and (1985), Gerin & Combes by posed .NMRCLMODELS NUMERICAL 3. p n h dpe asdistribution mass adopted the and , ıa- ıa- in,w aepromdtefloigsteps: following the performed have we tions, aaee a hneapeibytefia global this final of the variations value appreciably small morphologies. the change very to can model speed: parameter the pattern of the sensitivity of the on based • nodrt opr h oe ihteobserva- the with model the compare to order In ene odrv h tla oeta o both for potential stellar the derive to need We hnteselrds.Frtevria ocs we forces, vertical the For thinner disc. much stellar is the disc than gas molecular the that fact of pendent oprdwt htcntutdfo H from curve constructed rotation that adopted with the compared shows trac- 4 gaseous Figure the ers. from adopting curve after observational simulations of the run first a by central rated the than M/L reliable more constant H seems a it as assuming adopted ratio, obtained we Finally, curve ob- the simulations. morphology the final in the tained in curves differ- of the rotation influence ent of the test determination will we bad curve rotation a to the eliminate due To uncertainty curve. neces- rotation observed profile corresponds the that to the density surface fitted a obtain we to step, sary second the In ihtebs uv bandfo interstellar from obtained curve H best the with ocsi h ln ( gravitational assume plane the the we in simplicity thus, forces of symmetry; sake cylindrical the For galaxy. third a in potential dimensions, direction gravitational 3 the in extend we performed are simulations As data. HI aeegh.TeIbn mg,wt spatial a 0 with of image, resolution red I-band the The affect mass wavelengths. dramatically the not of does dust tracer absorption where galaxies good spiral normal a in is distribution but image image, I-band infrared an tracer the be best would purpose The this for simulations. numerical of runs h ln fteglx suiga inclination an 53 in assuming of galaxy angle projected the then of and plane the stars galactic of cleaned increfo h oe,wihi compared is which model, the from curve tion faglrsz 1 size angular of iesoa atsa rdo 512 the of via grid two a Cartesian potential uses dimensional method the FFT The and equation. derived Poisson’s curve and rotation distribution mass the a a assuming into first, tribution steps: two constant in method. Transform proceeded Fourier We Fast a using puted α α msinosrain Rzse l 2000b). al. et (Rozas observations emission n Idt.Ti on a encorrobo- been has point This data. HI and M/L z ◦ epniua otepaeo the of plane the to perpendicular , z h rvttoa oeta scom- is potential gravitational The . hsasmto sbsdo the on based is assumption This . . ecnetdtebihns dis- brightness the converted we 9pxladasen f1 of seeing a and 59/pixel × F 1 x n edrvdarota- a derived we and , and F y ocs r inde- are forces) × 1 pixels 512 α ,was and © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México ie.()Temi eoacssproe nteH the on straight superposed as resonances shown main are image. The open speeds (b) and pattern Filled two lines. The curve. H tively. rotation the Adopted are (a) squares 4. Fig. p sacaatrsi egt The height. characteristic a as kpc 2 ml n hyd o aelreexcursions neglected. val- be real large can the make from ues deviations is not thus, clouds disk; do the the from they of and length the small but Pois- satisfy forces equation, not The son’s do method this distribution. with this calculated from derived are iru fa nnt ae ihadniylaw density a with equi- layer the infinite ρ obeys an layer of stellar librium each that assume = ρ 0 sech 2 ( α z/H n Iosrainldt,respec- data, observational HI and YAIA OE O H PRLGLX G 3977 3359 NGC GALAXY SPIRAL THE FOR MODEL DYNAMICAL ,weew aeadopted have we where ), F z forces H = α • ntefis oe oa ubro 4 of number total a model first the In ico cl length exponential scale an 1987). of is disc al. distribution et radial Solomon initial The (e.g. clouds molecular of er,vr ag lus(ihmse bigger masses (with clouds 3 than large very years, aineet:atraGClf-ieo 4 of life-time GMC a after for- events: star simulated mation via lost re-injected energy is The collisions by run. the mass during coalescence, conserved total being the be fragmentation, can or exchange results mass col- final inelastic whose via interact lisions, and from image, test computed I-band as potential the stellar move the spheres, in as particles modelled multi- clouds, The a of equilibrium the system. component Gaussian, from is expected plane the as to perpendicular bution iigtecod ml eoiydseso of dispersion s velocity km small 10 a clouds and axisym- the velocity giving rotational the its in with potential clouds metric begin molecular we simulations launching numerical by of runs both In the to bar stellar potential. and arms spiral con- the the of represents tribution and part potential, total axisymmetric the the from of subtraction by ob- tained is component non-axisymmetric The radius. the is part symmetric The parts. next axisymmetric gravita- The total the bar. decomposing stellar of the consists and step arms spiral the osatptensedΩ speed pattern constant a nrdcdgaulywt 0 ea fthe (7 of run delay the of 20% time a total with gradually introduced lusaedsrbtdacrigt mass a 10 to from according ranging distributed spectrum are clouds ece us-ttoaystate. quasi-stationary has a and reached structure cre- non-axisymmetric well the potential by the ated into trapped been has gas f1 ms velocity km in random 10 reinjected a of with are medium which interstellar clouds the small of lection ercds.Tettlsmlto ieo run a of time 7 simulation is total axisym- The an in disc. the distribution metric ensures cloud and the collisions of the stability in lost energy the oi&Cme 92,adtersaeflosa follows scale their and ( 1982), Combes & soli zmta vrg ftettlptnilfreach for potential total the of average azimuthal non- and axisymmetric its into potential tional includes field, potential real the closely to approximate intended potential, gravitational The M cloud . 4 × × ) − 1 10 / 1 10 2 − h o-xsmercptnilis potential non-axisymmetric The . 8 1 5 a,a stpclfra ensemble an for typical is as law, hsvlct iprinbalances dispersion velocity This . M er.Atrti iemolecular time this After years.  r iitgae noacol- a into disintegrated are ) a d . p n h distri- the and kpc 3.8 = . 8 × p 3 10 . o10 to 8 er)adwith and years) 6 M  × × (Ca- 10 10 7 4 © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México atr pe o ieetvle fteaglrvlct.Tecnrlbri o te ytemdlad particularly, and, model the by fitted not is bar central The reproduced. velocity. not angular is the structure of nuclear values the different for speed pattern i.5 otuso h H the of Contours 5. Fig. ROZAS 78 • ntescn oe eitoue h efgrav- self the introduced we model second the In e.Tenurlhdoe aso G 3359 0 NGC is (1982) of Gottesman mass by hydrogen detected neutral cen- the The in emission galaxy ter. CO this strong that present fact not the does note They kpc). (inner 92 rel ez19) rie&Combes & Braine log a 1993). calculate (1992) Benz & Friedli 1992; oa tla asifre rmorrdiaeis image red our The M from galaxy. be- inferred the mass the of stellar analyze center total the better in to gas the order of in havior gas the of ity efgaiaini h lblds ol o be not could if disc important very global the in self-gravitation D e oterltv eoiybtentocolliding two is between clouds velocity relative of the value to paral- direction lel The the in parameter inelasticity collisions. the inelastic partially via aetesm as 10 to mass: clouds same all or- the assumed particle have arbitrarily the have for- We follow star better bits. the to suppressed events have mation sim- we the of not plots picture is clear that ulation a self-gravitation suppose obtain gas To can to important. we due atomic spirals, influence to type the molecular late of for ratio gas normal a assume 2  ,or2 =3 . . 9 7 ∼ × × .5ad1i h ieto perpen- direction the in 1 and 0.65 10 10 9 10 M M  M  for g α h nunedet gas to due influence The . / M M mg uepsdo h eut ftenmrclsmltospromdwt unique a with performed simulations numerical the of results the on superposed image D H  3 2 34Mc n fwe if and Mpc; 13.4 = M ≤ . o h nucleus the for 7.4 =  . Wd Habe & (Wada 0.1 lusinteract Clouds . . 015 × 10 9 × etdeiso ftecod sn eecp beam 12 telescope a of using halfwidth clouds the of emission pected oe.I iue5w hwcnor fteH the of contours show speed, we the 5 pattern by Figure matched unique In not a is model. morphology tried inner we the first, though At s values. km 3 and dimensions spatial the in ltospromdwt nqeptensedfor speed pattern sim- unique numerical a the with of performed results ulations the on superposed age oeua lu rwigfco slwfralcloud all for low is the velocities). factor (i.e. crowding clouds cloud in in- molecular thin the optically of that is assumption maps medium the terstellar simulated under produce gas we molecular of mod- the images, our velocities the of radial results with the the els compare and to sky, Then, the clouds. the of plane the on ehv are u eea uswt ieetΩ different with runs several out carried have We .CMAIO EWE H MODEL THE BETWEEN COMPARISON 4. aacb sbitb ovligteex- the convolving by built is cube data A fe ahrnw tr h oiin projected positions the store we run each After F ehdadaddt h moe stellar imposed the to an added by computed and been method have FFT gravitational gas the The to due moment. forces angular conserva- the the of assure to tion encounter the to dicular oeta Cme ta.1990). al. et (Combes potential N H OBSERVATIONS THE AND h elsz ftecb s6 is cube the of size cell The ˙ − 1 nvelocity. in α × im- 6 p © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México h Ω the Tge ta.18) iue4sostetocir- two the one precession shows slow Lindblad Ω 4 the the frequencies, Figure and of velocities region 1987). angular cular ILRs al. the et the in of (Tagger is by corotation the constrained pattern resonances: is fast the speeds of angular location the the of choice The hsfiuew hwterdio h anresonances main the H of the radii on the overlaid show we figure this eoac slctdi h ue ica aisof radius a Lindblad at disc outer outer An the 130 in disc. located optical is the resonance of middle the 20 iuain rm10t 6 y ihteadopted the with Myr 960 to 120 from simulations predicts. theory the as speed pattern fast s ftedniywv,i oae tardu f95 of radius a speed at pattern located the is to wave, equal density is the Ω of matter the of locity i.6 ieetseso h ueia iuain rm10t 6 y ftetoptensedmdl ihthe with model, speed pattern two the of Myr 960 to 120 from simulations numerical the of steps Ω adopted Different 6. Fig. ieetvle fΩ of values different y,adtencerbr h w atr speeds pattern Ω two are observations The the 150 reproduce of bar. best delay that nuclear which a the with spiral, and simulations outer Myr, the + in introduced main non- is the the different velocities: when with angular bars obtained decoupled two two is in representing divided parts fit pattern is component different best potential two axysimmetric The with model a speeds. for only tained reproduced. not structure nuclear certainly the is particularly, and, model the by − 1 iue6sosdffrn tp ftenumerical the of steps different shows 6 Figure prlsrcuesmlrt htosre sob- is observed that to similar structure spiral A h aepaeo h ooainrdu fthe of radius corotation the of place same the : kpc n nIL oei iutda aisof radius a at situated is zone IRLs an and , s − =27kms 1 s n Ω and =27kms − f κ/ α − 0 ms km 100 = 2andΩ+ mg:tecrtto aisfor radius corotation the image: 1 p − h eta a sntfitted not is bar central The . YAIA OE O H PRLGLX G 3979 3359 NGC GALAXY SPIRAL THE FOR MODEL DYNAMICAL kpc 1 kpc − 1 − hr h nua ve- angular the where , 1 − κ/ o h lwmi a ue prladΩ and spiral outer + bar main slow the for 1 ,vru ais In radius. versus 2, kpc − 1 respectively. s =27km in ovlto ota (,n (,)=1 hnF then 1, = F(o,o) = n) between the F(n, changes normalize intensity that and best function so mean the are convolution the from data it calculate subtract the we and where When largest is measured. real W(x,y) the matches model image. the function well weight how a measures which is W(x,y) and respectively, image, orlto,adta h oe ihΩ with model the that and correlation, n I and ffiinssoni al .Temethod The integral convolution a 2. creating co- Table in F(n,o)=I correlation consists in the used gives shown method efficients regression ear ue prl nbt ae h etfi sobtained is fit above. mentioned best speeds the pattern cases two the both for In the with spiral. agreement the outer show 7a to respectively, Figures in 7b, displayed and from are obtained model gravitating map self intensity the H modelled the and the map on contours HI image the of overlays The bar. h bv etoe aus h o fnegative of row The are values. results best mentioned the above that the conclude we eye, by models ± ota od okn ttoenmes ewould we Ω numbers, both those at that Looking say good. as most prladΩ and spiral a e rmtenmesi al ,ta h mod- the that 2, Table Ω We in with match. numbers els the the of from value see best can the +1 and value worst h iuain n h H the and simulations the Ω s % n oelikely more and 5%, =27kms uniaiecmaio fterslsof results the of comparison quantitative A obs r h neste ftemdladtereal the and model the of intensities the are model s 2 n Ω and =27 f f − 0 ms km 100 = ( 1 x,y 0 ms km 100 = kpc f ) − *I n Ω and 1and+1, − obs 1 f ( o h lwmi a outer + bar main slow the for 10ad15hv h same the have 105 and =100 x,y ± − s 0.Bteaiigthe examining But 10%. 1 ) Wxy,weeI where *W(x,y), − r neti oa least at to uncertain are kpc 1 kpc α − − 1 ersnigthe representing 1 o h ula bar. nuclear the for − mg yalin- a by image 1 o h nuclear the for s 2 sal- is =29 model α © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México oiygainsaon h a on yRzset Rozas by ve- found the bar with the agree around gradients which a locity delineating velocity structure; motions the spiral streaming distribution. of patchy strong gas in overlay see modeled a present can the We is both with 8b are (contours) Figure field spiral peak mini model. two the the the simulations; and numerical the maxima of fit best riscag t retto y90 by periodic orientation its interpreted: change easily orbits be can but striking quite ubr nteclm o 0k s km 90 for column the in numbers H resonance. a over ihteotrsia.()Tesm o h H the for same The agreement (b) fit the spiral. best see outer the can the on We map with simulations. contour numerical HI the the of of Overlay (a) 7. Fig. ROZAS 80 α iue8 hw h eta ato h galaxy: the of part central the shows 8a Figure otuso h eta a uepsdo the on superposed bar central the of contours ◦ − hnte cross they when 1 kpc − α 1 image. sthen is lofidi luil htgscmrsinaccompa- compression gas that plausible it find also crucial a be to gas the in viscosity found of They degree from the that potential. decoupling gravitational and underlying rings the nuclear their from and galaxies, formation barred in bars gaseous gravitating model. ainpoess lhuhNC42 a been cor- behavior has kinematical 4321 its for- NGC late-type, star as Although and classified properties bar processes. of mation variety large a deter- found mine that have characteristics as we 157, kinematical such different NGC very and spirals 7479 late-type NGC 4321, other NGC in resonances main a be to morphological appears and characteristics. dynamical 3359 these NGC both kinemat- with 2000b). its galaxy from al. 3359 et NGC (Rozas in ics the observed across is circulation as gas ILRs, with and bursts formation with star They associated of be can bars. decoupling, such primary nying the to pat- slower compared much speeds having state, tern bars decoupled gaseous fully a nuclear a spend in with time to systems. of expected these period are substantial of systems evolution low-viscosity diverging The the in factor non-self- of characteristics the of analysis an formed kpc einfo rm oaiga Ω at rotating frame a from region galaxies. early-type to galaxy galaxy, related this the more shows of be coexist to can zone bars central nested pat- the two two in where a model to speed corresponds fact tern dynamics the but global spiral, the classifi- late-type a that the process as with 3359 the NGC agrees in of scenario bar cation This a forma- of star formation. scenario strong of general of with the region together fits bar This, tion the in parts. presence inner po- the the barlike in the by field driven tential circulation gas H oval the highly in (2000b) al. 90.60 29 10.59 31 50.56 25 70.58 27 10.52 21 Ω 30.61 23 s ORLTO OFIINSO THE OF COEFFICIENTS CORRELATION elr homn nlae 20)per- (2001) Englmaier & Shloaman, Heller, rmtedtriaino h oiino the of position the of determination the From iue9sostepril risi h nuclear the in orbits particle the shows 9 Figure − Ω 1 f o h etfi eouino h w pattern two the of resolution fit best the for 59 5101510115 110 105 100 95 90 85 IERREGRESSION LINEAR − − − − − − 0 0 0 0 0 0 ...... 407 .707 .70.64 0.67 0.77 0.77 0.74 64 006 .607 .40.59 0.64 0.74 0.76 0.69 60 606 .307 .20.57 0.62 0.71 0.73 0.68 56 406 .207 .70.64 0.67 0.71 0.72 0.68 64 506 .207 .60.63 0.66 0.70 0.72 0.68 65 405 .006 .60.54 0.56 0.69 0.70 0.58 54 α AL 2 TABLE ieais n xlie as explained and kinematics, s =27kms − 1 © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México oe.()Oelyo h eoiyfil cnor)on (contours) the field velocity in distribution. the present gas of both modeled peaks Overlay the are two (b) spiral The mini model: model. the the of and fit (maxima) best the on superposed airi prl ftesm ye tsesmore of seems basis properties. It morphological the and on kinematical their type. galaxies both spiral same classify the to of appropiate spirals in havior i.8 a H (a) 8. Fig. ttecne fteisrttoa curve. rotational its maximum the local of a center characteris- as the some such at has galaxies, it early-type but of types, tics late gen- of the trend an follow eral dynamics be by its could since 157 late-type case, NGC a intermediate (1993). for Elmegreen predicted & characteris- speed Combes bar On pattern the and galaxy. shows tics early-type 7479 an NGC of contrary, that the to more responds hs ecnfidvr ieetdnmclbe- dynamical different very find can we Thus, α eta oeo h aay(contours) galaxy the of zone central YAIA OE O H PRLGLX G 3981 3359 NGC GALAXY SPIRAL THE FOR MODEL DYNAMICAL fteglx,weegssl-rvt a lya im- an play can arms role. self-gravity the portant gas in where and galaxy, center the the of at more behavior in gas analyze the to detail in- order in and self-gravity events gas col- the formation cludes simulated. inelastic star the partially are suppresses considers formation lisions, model star model second a in of The self-gravity, is effects without one the first collisions which the cloud inelastic models: of two run have We pe oe hwn h atceobt ntecentral the in orbits particle pattern two the the region. of showing solution fit model best the speed for frame A 9. Fig. oprdwt e fosrain (H observations of set a with compared reprmtrta evr norsmltosi Ω is simulations with our in galaxy vary only we the the that ratio, parameter of light free to image mass about red assumptions mass some a the obtained from have we distribution produces Since which and curve. galaxy, wave, rotation the the the in of distribution speed mass the pattern the are simulations real the from far is speed pattern one. chosen morphol- the observed if the ogy, from to significantly morphology depart tends resulting can the gas and the orbits, different speeds: periodic follow pattern of poten- different stellar family with given the a tial, in that different is completely of is idea density orbits structure The the spiral plus of 3359. bar NGC speed the pattern for responsible the wave determine to der h eut fnmrclsmltoshv been have simulations numerical of results The ehv are u ueia iuain nor- in simulations numerical out carried have We h otsniieprmtr ntenumerical the in parameters sensitive most The .CONCLUSIONS 5. α ,HI)to p . © Copyright 2008: Instituto de Astronomía, Universidad Nacional Autónoma de México 2ROZAS re- main follows: the as summarize work We this of fit. sults best the for search 82 .Tecrtto aisfrteso atr speed pattern slow the for radius corotation The 3. .NC35,casfida aesia galaxy, late-spiral a as classified 3359, NGC 7. is 3359 NGC for proposed model dynamical The 6. .OrsmltosrpoueteH the reproduce simulations Our 4. .Tebs opooia ti on o two a for found is fit morphological best The 2. .W aetidt ttemrhlg fthe of morphology the fit to tried have We 1. .Teaayi ftenncrua oin around motions circular non the of analysis The 5. s rhls,tepeec fabri formation a in bar a Nev- of galaxies. presence galaxy, early-type the this the the ertheless, relates to coexist, of rather can galaxy zone bars nested central two the where in global The dynamics 1993). bulge-less Elmegreen typical & a (Combes galaxy for predicted speed and characteristics pattern bar typical the show not does h aepaeo h ooainrdu fthe predicts. of theory the radius as corotation 20 speed, the of pattern radius of fast a place at same situated is the zone IRLs an and ms km slctda aiso 95 of radius a at located is slctdi h ue ica aiso 130 of radius a at disc resonance outer the Lindblad in outer located An is disc. optical the a ue prlrttswt Ω a with rotates spiral main outer the + velocities: bar angular different with bars decoupled two representing model speed pattern trfrainadgsiflwars h IRLs, this of decoupling. the accompanying bursts compression across gas expect inflow with we related gas case that and this formation speed In nuclear star pattern a bar. slower main with much the state, a decoupled having a bar substan- in a time spends which tial 2001) al. sys- et low-viscosity (Heller a tem is 3359 NGC model that this suggest From we morphology. the by confirmed strong formation. bar of of a process of region the scenario in general bar the the fits formation, in together star presence This, the the bar. explains with the (2000b) around in flowing orbits gas al. as elliptical region et this in Rozas gradients velocity in bar the ue ytemodel. repro- the be by cannot duced galaxy the of structure nuclear aayt oe osrce ihaunique Ω a of values with different constructed with speed, model pattern a to galaxy ekmxm n h iisia r rsn in present are model. mini-spiral the the and twin maxima the peak structures: inner the including vations, − 1 kpc − 1 − kpc 1 n h ula a ihaΩ a with bar nuclear the and , − 1 . ntemdl of middle the in α n Iobser- HI and s =27km f p 100 = .The , : fnie,D,&Nra,C .19,AJ 6,391 363, ApJ, 1990, A. 161 C. 445, Norman, ApJ, & 1995, D., R. 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