Interacting Pairs of Elliptical Galaxies

Davoust, E.; Prugniel, Ph.; Arnaud, J.

doi:10.1007/978-1-4613-9356-6_50

Cited by 32 publications

(39 citation statements)

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“…A K-S test shows that there is only a 3% probability that the luminous and the faint cluster samples were drawn from the same parent population. This conclusion strengthens and confirms a similar result by Davoust & Prugniel (1990) who, however, neglected to take into account the effects of absorption on the apparent flattening of globular clusters.…”

Section: Flattening Of Galactic Globular Clusterssupporting

confidence: 91%

“…Furthermore, Davoust & Prugniel (1990) discovered that the most luminous globulars in M31 and the Galaxy are rounder than intrinsically fainter globular clusters. It is the purpose of the present paper to re-investigate these conclusions taking into account the fact that the apparent flattening of clusters can be strongly affected by patchy asymmetric foreground absorption (van den Bergh 1983b).…”

Section: Introductionmentioning

confidence: 99%

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The Flattening of Globular Clusters

Bergh

2008

The Astronomical Journal

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In the three nearest luminous galaxies, the Milky Way System, the Andromeda Galaxy, and NGC 5128, the brightest globular clusters are rounder than the faintest ones. On the other hand (contrary to some previous results) the flattening of individual Large Magellanic Cloud clusters is found to be independent of their luminosities. This suggests the possibility that the relationship between the flattening and luminosity of clusters might depend on host galaxy luminosity. No significant differences are found between the intrinsic flattening distributions of Galactic old halo, Galactic young halo, and Galactic bulge/disk clusters. Such a dependence might perhaps have been expected if tidal forces (which are largest at small Galactocentric distances) removed angular momentum from globular clusters. The preliminary conclusion by Norris that clusters with blue horizontal branches are more flattened than red horizontal-branch (HB) clusters is not confirmed by the larger database that is now available. In other words there is no evidence for the puzzling claimed correlation between the flattening and the horizontal branch morphology of Galactic globular clusters.

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Section: Flattening Of Galactic Globular Clusterssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

The Flattening of Globular Clusters

Bergh

2008

The Astronomical Journal

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“…Some pairs present a common pattern of distortion interpreted in terms of tidal effects (Davoust and Prugniel, 1988;. Other examples drawn from the literature (Borne and Hoessel, 1988;Colina and Perez-Fournon, 1990) share the same morphology.…”

mentioning

confidence: 83%

“…One is an optical pair (VV 190). Eighteen of our pairs present the morphological effect described in Davoust and Prugniel (1988): the external parts of each member are stretched in opposite senses in a direction roughly perpendicular to the pair axis. The proportion of 15±4% distorted pairs confirms previous estimates.…”

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confidence: 94%

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Tidal distortions in pairs of early-type galaxies

Prugniel

Davoust

1990

International Astronomical Union Colloquium

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We are conducting an imaging survey of pairs of elliptical galaxies which has already produced interesting results. Some pairs present a common pattern of distortion interpreted in terms of tidal effects (Davoust and Prugniel, 1988;. Other examples drawn from the literature (Borne and Hoessel, 1988;Colina and Perez-Fournon, 1990) share the same morphology. This Poster presents new cases and lists the characteristics of 24 such systems. Our pairs are drawn from a sample of binary and multiple galaxies which has in turn been extracted from the CGCG, UGC (Nilson, 1973) and VV (Vorontsov-Velyaminov, 1959) catalogues. This sample includes that of Karachentsev (1972). It contains 1800 pairs, among which 700 are S -S or mixed morphology pairs. We are working on the remainder to produce a sample of close physical pairs of elliptical galaxies (we also include bulge dominated SO's since the morphological discrimination from ellipticals is often ambiguous, in particular for interacting galaxies).One of the interests of this work is to provide a sample selected on purely optical criteria, at variance with other works (e.g. Valentijn and Casertano, 1988). This will allow statistical studies of non-optical properties of these pairs (in particular radio emission).We have so far obtained CCD-images of 125 pairs with the 2 m telescope of Pic du Midi in V and/or R. Velocities and velocity differences of 78 pairs have been obtained using the 1.93 meter telescope of Observatoire de Haute Provence and from the literature. One is an optical pair (VV 190). Eighteen of our pairs present the morphological effect described in Davoust and Prugniel (1988): the external parts of each member are stretched in opposite senses in a direction roughly perpendicular to the pair axis. The proportion of 15±4% distorted pairs confirms previous estimates.Except for a few cases involving flattened galaxies with nearly aligned major axes which deserve careful detailed analysis , the apparent distortions do correspond to physical distortions. We have searched the literature for isophote maps showing this effect. In the survey of radio galaxies by Colina and Perez-Fournon (1990), 7 out of 20 pairs show this characteristic distortion. Such a high rate (35%) suggests a relation between the strength of the interaction and radio activity (if we consider that the magnitude of the distortion is related to the strength of the interaction).On the other hand, among the optically selected distorted pairs, 42% are radio galaxies while only 5% of all E-E Karachensev pairs axe detected in radio (Stocke, 1978; this proportion rises to 7% if we only consider pairs with a separation of less than 10 kpc). This is not a rigorous statistical analysis since thresholds for radio detection and also for distortion detection are not 65

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Polarimetric imaging of interacting pairs

Rampazzo¹,

Bonoli

Giro

2008

Astron Nachr

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We present optical polarization maps of a sample of four interacting pairs at different phases of encounter, from nearly unperturbed galaxies to on-going mergers. Only the pair RR 24 shows a linear polarization pattern which extends in both galaxies for several kiloparsecs. The more perturbed member, RR 24b, is lineraly polarized up to the level of ~3%. No polarization is measured in the strongly perturbed late-type pair members of RR 23 and RR 99. Also, in the central part of the double nuclei shell galaxy ESO 2400100 there is no significant polarization. We use the ionized gas velocity field of RR 24 to interpret its linear polarization structure. In RR 24a the quite regular gas kinematics reflect the unperturbed spiral-like polarization structure. In RR 24b a strong velocity gradient in ionized gas could be associated with the polarization structure. We suggest that the large-scale magnetic field of the RR 24 pair members still plays a role in shaping the polarization pattern.Comment: 9 pages, 5 figures, accepted for publication in A

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Interacting Pairs of Elliptical Galaxies

Cited by 32 publications

References 4 publications

The Flattening of Globular Clusters

The Flattening of Globular Clusters

Tidal distortions in pairs of early-type galaxies

Polarimetric imaging of interacting pairs

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