Bioastronomie

Heidmann, J.

doi:10.1007/978-3-642-78445-3

Cited by 29 publications

(34 citation statements)

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“…Hints of increasing thickness for less massive galaxies are not new (e.g. Heidmann et al 1972;Yoachim & Dalcanton 2006), but to our best knowledge we are the first to identify a characteristic mass below which low-mass galaxies start to be systematically thicker. The question then arises naturally.…”

Section: Discussion a N D C O N C L U S I O N Smentioning

confidence: 85%

“…They are said to be thin because their C 2010 The Authors. Journal compilation C 2010 RAS vertical-to-radial axial ratios have long been known to lie in a narrow range 0.15 q 0 0.25 (Holmberg 1950;Sandage, Freeman & Stokes 1970;Heidmann, Heidmann & de Vaucouleurs 1972). However, this thickening is not uniform, as late-type spirals have thinner discs than early types (Bottinelli et al 1983;Guthrie 1992).…”

Section: Introductionmentioning

confidence: 99%

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Thin discs, thick dwarfs and the effects of stellar feedback

Sánchéz-Janssen

Méndez-Abreu

Aguerri

2010

Monthly Notices of the Royal Astronomical Society: Letters

115

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We investigate the role of stellar mass in shaping the intrinsic thickness of galaxy discs by determining the probability distribution of apparent axis ratios (b/a) for two different samples that probe the faint end of the galaxy luminosity function. We find that the b/a distribution has a characteristic 'U-shape' and identify a limiting mass M_* ~ 2x10^9 M_sun below which low-mass galaxies start to be systematically thicker. This tendency holds for very faint (M_B ~ -8) dwarfs in the Local Volume, which are essentially spheroidal systems. We argue that galaxy shape is the result of the complex interplay between mass, specific angular momentum and stellar feedback effects. Thus, the increasing importance of turbulent motions in lower mass galaxies leads to the formation of thicker systems, a result supported by the latest hydrodynamical simulations of dwarf galaxy formation and other theoretical expectations. We discuss several implications of this finding, including the formation of bars in faint galaxies, the deprojection of HI line profiles and simulations of environmental effects on the dwarf galaxy population.Comment: 6 pages, 2 figures. Accepted for publication in MNRAS Letter

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Section: Discussion a N D C O N C L U S I O N Smentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Thin discs, thick dwarfs and the effects of stellar feedback

Sánchéz-Janssen

Méndez-Abreu

Aguerri

2010

Monthly Notices of the Royal Astronomical Society: Letters

115

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“…Therefore, future observations on (1) the age and metallicity distributions of halo stars in Magellanic-type dwarf disc galaxies and (2) statistical correlations between the presence of the outer stellar haloes and that of the faint thick disc components will help us to determine whether the stellar haloes in such dwarfs are formed from tidal galaxy interaction rather than from primordial merging/accretion of subgalactic clumps. Heidmann, Heidmann & de Vaucouleurs (1972) revealed that the intrinsic flattening in disc galaxies decreases (i.e. less flattened) abruptly from Sm to Im Hubble types.…”

Section: Stellar Halo Formation In the Lmc And Magellanic-type Dwarfsmentioning

confidence: 98%

Formation and evolution of the Magellanic Clouds - I. Origin of structural, kinematic and chemical properties of the Large Magellanic Cloud

Bekki

Chiba

2005

Monthly Notices of the Royal Astronomical Society

155

212

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We investigate the dynamical and chemical evolution of the Large Magellanic Cloud (LMC) interacting with the Galaxy and the Small Magellanic Cloud (SMC) based on a series of self‐consistent chemodynamical simulations. Our numerical models are aimed at explaining the entire properties of the LMC, i.e. the observed structure and kinematics of its stellar halo and disc components as well as the populations of the field stars and star clusters. The main results of the present simulations are as follows. Tidal interaction between the Clouds and the Galaxy during the last 9 Gyr has transformed the initially thin, non‐barred LMC disc into three different components: central bar, thick disc and kinematically hot stellar halo. The central bar is composed of both old field stars and newly formed ones, with the two fractions being equal in its innermost part. The final thick disc has central velocity dispersion of ∼30 km s−1 and shows rotationally supported kinematics with Vm/σ0∼ 2.3. The stellar halo is formed during the interaction, and consists mainly of old stars originating from the outer part of the initially thin LMC disc. The outer halo shows velocity dispersion of ∼40 km s−1 at a distance of 7.5 kpc from the LMC centre and has a somewhat inhomogeneous distribution of stars. The stellar halo contains relatively young, metal‐rich stars with a mass fraction of 2 per cent. Repetitive interaction between the Clouds and the Galaxy has moderately enhanced the star formation rate to ∼0.4 M⊙ yr−1 in the LMC disc. Most of the new stars (∼90 per cent) are formed within the central 3 kpc of the disc, in particular, within the central bar for the last 9 Gyr. Consequently, the half‐mass radius is different by a factor of 2.3 between old field stars and newly formed ones. Efficient globular cluster formation does not occur until the LMC starts interacting violently and closely with the SMC (∼3 Gyr ago). The newly formed globular cluster system has a disc‐like distribution with rotational kinematics, and its mean metallicity is ∼1.2 higher than that of new field stars because of pre‐enrichment by the formation of field stars prior to cluster formation. The LMC evolution depends on its initial mass and orbit with respect to the Galaxy and the SMC. In particular, the epoch of the bar and thick disc formation and the mass fraction of the stellar halo depend on the initial mass of the LMC. Based on these results, we discuss the entire formation history of the LMC, the possible fossil records of past interaction between the Clouds and the Galaxy, and the star formation history of the SMC for the past several Gyr.

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“…Although we do not know for sure the inclination of the nuclear discs, we will assume that the vast majority of them will have the same inclinations of their host galaxies, which is justified if we consider our sample galaxies as oblate axisymmetric spheroids. The LEDA data base provides inclination estimates for the host galaxies based on the method applied by Heidmann, Heidmann & de Vaucouleurs (1972) and Bottinelli et al (1983). The inclination was calculated assuming that all galaxies of a given Hubble type had an axis ratio equal to that observed in the flattest galaxy of that type.…”

Section: Inclinationmentioning

confidence: 99%

A census of nuclear stellar discs in early-type galaxies

Ledo

Sarzi

Dotti

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Nuclear stellar discs (NSDs), of a few tens to hundreds of parsec across, are a common and yet poorly studied feature of early-type galaxies. Still, such small discs represent a powerful tool to constrain the assembling history of galaxies, since they can be used to trace to the epoch when galaxies experienced their last major merger event. By studying the fraction and stellar age of NSDs, it is thus possible to test the predictions for the assembly history of early-type galaxies according to the current hierarchical paradigm for galaxy formation. In this paper we have produced the most comprehensive census of NSDs in nearby early-type galaxies by searching for such discs in objects within 100 Mpc and by using archival images from the Hubble Space Telescope. We found that NSDs are present in approximately 20 per cent of early-type galaxies, and that the fraction of galaxies with NSDs depends neither on their Hubble type nor on their galactic environment, whereas the incidence of NSDs appears to decline in the most massive systems. Furthermore, we have separated the light contribution of 12 such discs from that of their surrounding stellar bulge in order to extract their physical properties. This doubles the number of decomposed NSDs and although the derived values for their central surface brightness and scalelength are consistent with previous studies, they also give a hint of possible different characteristics due to different formation scenario between nuclear discs and other kinds of large galactic discs

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Bioastronomie

Cited by 29 publications

References 0 publications

Thin discs, thick dwarfs and the effects of stellar feedback

Thin discs, thick dwarfs and the effects of stellar feedback

Formation and evolution of the Magellanic Clouds - I. Origin of structural, kinematic and chemical properties of the Large Magellanic Cloud

A census of nuclear stellar discs in early-type galaxies

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