Dust in elliptical galaxies

Sparks, W. B.; Wall, J. V.; Thorne, D. J.; Jorden, Paul; Breda, I. G. van; Rudd, P. J.; Jørgensen, H. E.

doi:10.1093/mnras/217.1.87

Cited by 55 publications

(34 citation statements)

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“…This is the case when comparing our data with the V − I map of NGC 1052 by Sparks et al (1985), or the maps of Goudfrooij et al (1994b), for NGC 2974. Discrepancies arise, when one of the intercompared surveys is of much lesser resolution, or perhaps affected by the effects here described as "differential seeing".…”

Section: Comparison With Other Surveyssupporting

confidence: 61%

“…A number of techniques have been experimented to reduce the noise in colour maps, or more exactly to increase the range of SuBr where this noise remains acceptable, including the one introduced long ago by Sparks et al (1985): they replace the redder of the pair of frames by a synthetic image built from a set of isophotal contours. It was concluded however that the improvement was not worth the extra work, since the frames studied here are useful only to measure the innermost range of galaxian colours.…”

Section: D Colour Mapsmentioning

confidence: 99%

“…Red nuclei in E-galaxies have been considered by Sparks et al (1985): they note "an unresolved nucleus 0.3 magnitudes redder than the surrounding galaxy" for NGC 6958. This description obviously refers to an artefact of differential seeing, according to the experiments described in Sect.…”

Section: Red Nucleimentioning

confidence: 99%

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Colour distributions in E-S0 galaxies

Michard

1999

Astron. Astrophys. Suppl. Ser.

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Abstract. The B − R colours distributions (with R in Cousins's system) have been measured in 44 E classified galaxies in the Local Supercluster, from pairs of frames collected by Nieto and co-workers in 1989-91. These are nearly all from the CFHT, and of sub-arsec resolution.Great attention has been given to the effects of unequal PSF's in the B and R frames upon colour distributions near centre; such effects are illustrated from model calculations and from pseudo-colours obtained from pairs of frames taken in the same band but with different seeing conditions. Appropriate corrections were systematically applied in order to derive central colours and inner gradients, although still affected by the limited resolution of the frames.The radial colour distributions have been measured in more detail than usual, considering separately the near major axis and near minor axis regions of the isophotal contours. Azimuthal colour distributions, in rings limited by selected isophotes, were also obtained. Dust "patterns", i.e. patches, lanes, arcs, ..., have been detected and mapped from the colour distributions. An ad hoc dust pattern importance index (or DP II) in a scale of 0 to 3, has been introduced to qualify their size and contrast.We have tried to find evidence of a diffuse dust concentration towards the disk, if one is apparent. Positive results (noted by the dd symbol) have been obtained for disky E's, whenever the inclination of their disk to the line of sight is large enough, and eventually also in the small isolated disks sometimes present in both boxy and disky galaxies.The red central peak occurring in many E-galaxies might be the signature of a central concentration of dust, also in cases where this peak is isolated rather than embedded in some extensive colour pattern. The properties Send offprint requests to: R. Michard Based on observations collected at the Canada-FranceHawaii Telescope and at the Observatoire du Pic du Midi.of the near centre colour profiles have been related to a classification of nuclear photometric profiles into "flat topped" and "sharply peaked" (equivalent to "core-like" and "power-law" in the terminology of Faber et al. 1997).The published here data include the following: . Short descriptions and codes for the characters of the B − R distribution of each object, and comparison to the results of recent surveys.. A table of the mean B − R at the centre and at two selected isophotes, a "core colour gradient" and the usual logarithmic gradient.. Maps of near core B − R isochromes and B isophotes for comparison. Images of the B −R colour distribution are made available in electronic form.

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Section: Comparison With Other Surveyssupporting

confidence: 61%

Section: D Colour Mapsmentioning

confidence: 99%

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Colour distributions in E-S0 galaxies

Michard

1999

Astron. Astrophys. Suppl. Ser.

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“…IC 1459 has a massive counterrotating stellar core (M ∼ 10 10 M , according to Franx & Illingworth 1988) and its outer stellar isophotes are twisted, an indication that the stellar body is triaxial. This galaxy shows dust absorption in the central 10 (Sparks et al 1985) and faint pseudo-arms in the outer part (r ∼ 3. 5 Malin 1985).…”

Section: Ic 1459mentioning

confidence: 96%

The gas content of peculiar galaxies: Counterrotators and polar rings

Bettoni

Galletta

García‐Burillo

et al. 2001

A&A

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Abstract. This paper studies the global ISM content in a sample of 104 accreting galaxies, including counterrotators and polar rings, which spans the entire Hubble sequence. The molecular, atomic and hot gas content of accretors is compared to a newly compiled sample of normal galaxies. We present results of a small survey of the J = 1−0 line of 12 CO with the 15 m SEST telescope on a sample of 11 accretors (10 counterrotators and 1 polar ring). The SEST sample is enlarged with published data from 48 galaxies, for which observational evidence of counterrotation in the gas and/or the stars has been found. Furthermore, the available data on a sample of 46 polar ring galaxies has been compiled. In order to explore the existence of an evolutionary path linking the two families of accretors, the gas content of counterrotators and polar rings is compared. It was found that the normalized content of cold gas (Mgas/LB) in polar rings is ∼1 order of magnitude higher than the reference value derived for normal galaxies. The inferred gas masses are sufficient to stabilize polar rings through self-gravity. In contrast, it was found that the cold gas content of counterrotators is close to normal for all galaxy types. Although counterrotators and polar rings probably share a common origin, the gas masses estimated here confirm that light gas rings accreted by future counterrotators may have evolved faster than the self-gravitating structures of polar rings. In this scenario, the transformation of atomic into molecular gas could be enhanced near the transition region between the prograde and the retrograde disks, especially in late-type accretors characterized by a high content of primordial gas. This is tentatively confirmed in this work: the measured H2/HI ratio seems larger in counterrotators than in normal or polar ring galaxies for types later than S0s.

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“…Morphologically, NGC 7507 has a smooth appearance without obvious shells or tidal structures (the feature reported by Tal et al 2009 had not been confirmed by Salinas et al 2012), except for a central dust lane (Sparks et al 1985). Salinas et al (2012) showed the central dust structures in the colour map in short exposure images.…”

Section: Dust In Ngc 7507mentioning

confidence: 84%

The paucity of globular clusters around the field elliptical NGC 7507

Caso

Richtler

Bassino

et al. 2013

A&A

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Context. There is strong evidence that globular cluster systems (GCSs) of massive galaxies are largely assembled by infall/accretion processes. Therefore, we expect the GCSs of isolated elliptical galaxies to be poor. Although not completely isolated, NGC 7507 is a massive field elliptical galaxy with an apparently very low dark matter content. Aims. We determine the richness, the colour distribution, and the structural properties of the GCS of NGC 7507. Methods. We performed wide-field Washington photometry with data obtained with the MOSAIC II camera at the 4m-Blanco telescope (CTIO, Chile). Results. The GCS is very poor with S N ≈ 0.6. We identify three subpopulations with peaks at (C − T 1) colours of 1.21, 1.42, and 1.72. The bluest population may represent the old, metal-poor component. This interpretation is supported by its shallow density profile. The red population is more concentrated, resembling the galaxy light. The intermediate-colour population is strongly peaked in colour, and we interpret this population as the signature of a starburst whose age depends on the metallicity, but should be quite old, since no signatures of a merger are identifiable. In addition, we find a main sequence in the stellar foreground population, which we attribute to the Sagittarius dwarf tidal stream. Conclusions. The extrordinarily poor GCS of NGC 7507, a massive elliptical galaxy, is an illustration of how important the environmental conditions are for producing rich GCSs.

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Dust in elliptical galaxies

Cited by 55 publications

References 0 publications

Colour distributions in E-S0 galaxies

Colour distributions in E-S0 galaxies

The gas content of peculiar galaxies: Counterrotators and polar rings

The paucity of globular clusters around the field elliptical NGC 7507

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