Lifetime of density waves and classification of spirals

Feitzinger, J. V.; Schmidt-Kaler, Th.

doi:10.1017/s0074180900014388

Cited by 15 publications

(21 citation statements)

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“…3,1. DATENMATERIAL Das Datenmaterial (1323 Radialgeschwindigkeiten) ist in einem Katalog zusammengefaBt (Feitzinger und Weiss, 1979).…”

Section: Kinematik Und Dynamik Der Groflen Magellanschen Wolkeunclassified

“…Die Mitte der Kreisringbereiche (AR = 0~ gemessen in Grad, ist jeweils rechts oben markiert. GMW (R = 2?5) ist 0o = 188 ~ in bester Obereinstimmung mit den yon Feitzinger et al (1977) mit einer kleineren Datenmenge und der Gradientenmethode abgeleiteten Wert. Diese Obereinstimmung zeigt die Konsistenz der Methoden und die Verl/iBlichkeit der N/iherungsverfahren und Wichtungen.…”

Section: V(r O) = Vs + E(r O)unclassified

“…Als Zusammenfassung zeigt Abbildung 18 die ungeffihre dreidimensionale Anordnung der drei Sternsysteme (nach Daten von de Vaucouleurs, 1955;de Vaucouleurs und Freeman, 1973;Feitzinger et al, 1977). Der Beobachter befindet sich etwa in 60 kpc Entfernung vom galaktischen Zentrum.…”

Section: Gezeitenst6run9 Und Magellanscher Str6munclassified

“…Feitzinger et al (1977) haben die Raumorientierung dieses Systems neu bestimmt und finden ffir die Neigung des Systems i--= 33~ 3 ~ und ftir die Richtung der das aus allen Datenpunkten des Katalogs konstruierte Geschwindigkeitsfeld. Das Gebiet der GMW yon 8.~ x 8.02 wurde in 605 Einzelfelder yon 20' x 20 gerastert, die pro Feld abgeleiteten Mittelwerte umgekehrt proportional Abb.…”

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Galaxien vom Magellanschen Typ

Feitzinger

1980

Space Sci Rev

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In the first part of this paper the morphological structure of Magellanic type galaxies (Irr I) is investigated. The galaxies of Magellanic type present a basic pattern consisting of a disk, a bar, stellar arms, rudimentary or well developed, spiral filaments and condensations in the disk. With the help of this pattern a well-defined classification scheme is set up. The subgroup of Irr II-systems consists of normal galaxies which are more or less tidally disturbed. Bursts of star formation have a great influence on structure and colour ~f irregular galaxies.Using the ESO-B Atlas, 580 galaxies of Magellanic type (out of a sample of 3 ! 87 galaxies) were classified; 57 are new SB(s)m systems (prototype Large Magellanic Cloud). The sample shows dominant bar structures at the classification stages d-, din-, and m. A striking feature is the asymmetric position of bar and disk. This asymmetry is a general characteristic of galaxies of types SBd-SBm IB. The asymmetry can be discribed by a relative displacement parameter A = 0.78 • 0.15, defined as the quotient of small and great distance of the bar center to the optical edge of the disk. The displacement cannot be explained by tidal interaction with neighbouring galaxies.In the second part of the paper the kinematics and dynamics of the Large Magellanic Cloud (LMC) as the nearest and best-known example of a galaxy of Magellanic type is investigated. The main structural features of the LMC are disk, bar, rudimentary and well developed stellar arms as well as spiral filaments (not necessarily connected with density waves); the y-structure is a broken up ring structure. Embedded into these features are young, asymmetrically located spiral arm filaments. As an explanation for these structures stochastic start formation in an ordered chain reaction is proposed. The pattern of the spiral arm filaments is determined by the rotation curve. The morphological peculiarities of the LMC can also be detected in other galaxies of that type.The mean absolute displacement of the centers of bar and disk, determined from 18 galaxies, is A = 800 pc. The displacement between the bar center and the symmetry center of the rotation curve is of the same order.The presently known radial velocities of planetary nebulae, star clusters, H I and H II regions and stars belonging to the LMC have been collected in a catalogue as the basis of a discussion of the kinematics and dynamics of the LMC. Contrary to earlier work, we have used, for the first time, the radial velocities of objects of all subgroups together by a proper weighting scheme. Thus the basic kinematics and dynamics of the LMC has been deduced,The radial velocity field shows no ceniral symmetry; it is characterized by large scale (2-3 kpc) disturbances. By comparison with the velocity field of other _galaxies three main disturbances are identified: an oval distortion of the velocity field in the bar region, a radial velocity field around 30 Doradus, and disturbances connected with a warp or material above the disk in the southern quadran...

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“…3,1. DATENMATERIAL Das Datenmaterial (1323 Radialgeschwindigkeiten) ist in einem Katalog zusammengefaBt (Feitzinger und Weiss, 1979).…”

Section: Kinematik Und Dynamik Der Groflen Magellanschen Wolkeunclassified

Section: V(r O) = Vs + E(r O)unclassified

Section: Gezeitenst6run9 Und Magellanscher Str6munclassified

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Galaxien vom Magellanschen Typ

Feitzinger

1980

Space Sci Rev

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“…The inner arcsecond of R136, denoted R136a, is unresolvable by conventional ground‐based telescopes, and it was suspected that R136a is in fact a single stellar object of more than 3000 M ⊙ (Feitzinger et al 1980; Cassinelli, Mathis & Savage 1981). However, careful ground‐based work (both direct imaging: Moffat & Seggewiss 1983; Moffat, Seggewiss & Shara 1985 and speckle interferometry: Weigelt & Baier 1985) showed that R136a was not a single star.…”

Section: Introductionmentioning

confidence: 99%

VLT/SINFONI time-resolved spectroscopy of the central, luminous, H-rich WN stars of R136

Schnurr

Chené

Casoli

et al. 2009

Monthly Notices of the Royal Astronomical Society

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Using the Very Large Telescope's Spectrograph for INtegral Field Observation in the Near‐Infrared, we have obtained repeated adaptive‐optics‐assisted, near‐infrared spectroscopy of the six central luminous, Wolf–Rayet (WR) stars in the core of the very young (∼1 Myr), massive and dense cluster R136, in the Large Magellanic Cloud (LMC). We also de‐archived available images that were obtained with the Hubble Space Telescope's Space Telescope Imaging Spectrograph, and extracted high‐quality, differential photometry of our target stars to check for any variability related to binary motion. Previous studies, relying on spatially unresolved, integrated, optical spectroscopy, had reported that one of these stars was likely to be a 4.377‐d binary. Our study set out to identify the culprit and any other short‐period system among our targets. However, none displays significant photometric variability, and only one star, BAT99‐112 (R136c), located on the outer fringe of R136, displays a marginal variability in its radial velocities; we tentatively report an 8.2‐d period. The binary status of BAT99‐112 is supported by the fact that it is one of the brightest X‐ray sources among all known WR stars in the LMC, consistent with it being a colliding wind system. Followup observations have been proposed to confirm the orbital period of this potentially very massive system.

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The Stellar Content of 30 Doradus

Walborn

1984

Symp. - Int. Astron. Union

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The supergiant H II region 30 Doradus is placed in context as the optically most spectacular component in a much larger region of recent and current star formation in the Large Magellanic Cloud, as shown by deep Hα photographs and the new IRAS results. The current state of knowledge concerning the concentrated central cluster in 30 Dor is summarized. Spectroscopic information exists for only 24 of the brightest members, most of which are WR stars; however, photometry shows over 100 probable members earlier than BO. The spectral classification of these stars is a difficult observational problem currently being addressed; in the meantime their hypothetical ionizing luminosity is calculated from the photometry and compared with that suggested for the superluminous central object R136a alone, and with the H II region luminosity. With reference to related regions in the Galaxy, the likelihood that many of the brightest objects in 30 Dor are multiple systems is emphasized. An interpretation of R136a as a system containing a few very massive stars (as opposed to a single supermassive object) is in good accord with the observations, including the visual micrometer results. The study of 30 Dor and its central cluster is vital for an understanding of the numerous apparently similar regions now being discovered in more distant galaxies.

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Lifetime of density waves and classification of spirals

Cited by 15 publications

References 1 publication

Galaxien vom Magellanschen Typ

Galaxien vom Magellanschen Typ

VLT/SINFONI time-resolved spectroscopy of the central, luminous, H-rich WN stars of R136

The Stellar Content of 30 Doradus

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