1,725,100 research outputs found
Isotropic dynamical models of NGC 4472 (M 49)
No full textContext. The existence of dark matter in some early-type galaxies is well-established. We address one such case and study dynamical models of NGC 4472 by means of using both Newtonian and MOdified Newtonian Dynamics (MOND) approaches with particular emphasis on the latter.
Aims. We use the measurements of the radial velocities of globular clusters in NGC 4472 to test the predictions of dynamical models to fit a high and approximately constant value the velocity dispersion with radius for this galaxy.
Methods. The globular clusters of NGC 4472 are used as a tracer of the galaxy’s gravitational potential. We calculate the Jeans equation for both the Newtonian (mass-follows-light and dark-matter models) and the MOND approaches assuming spherical symmetry and isotropic orbits.
Results. We solve the isotropic Jeans equation for a spherical approximation and find, assuming a rotational velocity of 50 kms-1, that the isotropic Newtonian mass-follows-light models without dark matter cannot provide successful fits at radii larger than ~2 Re and that in the Newtonian approach dark matter is needed. Of the four different MOND models that we tested, two models can provide a successful fit to the velocity dispersion throughout the whole galaxy without assuming any anisotropy (again assuming a rotational velocity of 50 kms-1), thus showing that in the case of NGC 4472 MOND can describe the dynamics of a massive early-type galaxy with high values of velocity dispersion
Interactions Of The Dwarf Irregular Galaxy Ugc 7636 With The Giant Elliptical Galaxy Ngc 4472
No full textthis paper we present a study of the interactions of UGC 7636 with NGC 4472. Deep Washington CT 1 CCD images centered at NGC 4472 were obtained using the KPNO 4m telescope. In order to remove the smoothly varying background due to the halo light of NGC 4472, we have subtracted the model ellipitical galaxy from the original image. The photometry of point-like sources were obtained using the digital stellar photometry software IRAF/DAOPHOT
NEW WESTERBORK OBSERVATIONS OF THE HI CLOUD NEAR NGC-4472
No full textThe H I gas which hes between the giant Virgo elliptical NGC 4472 and the gas-deficient dwarf irregular UGC 7636 has been observed at high resolution and sensitivity with the Westerbork radio telescope. It is a concentration of gas at a projected distance halfway between the two galaxies, and at an intermediate velocity. There is a possible second clump of emission which provides additional evidence of gas infall towards the nucleus of NGC 4472, perhaps related to the giant's double radio source. The entire system is embedded (in projection) in the X-ray halo of the elliptical.</p
The gas dynamics of NGC 4472 revealed by XMM-Newton
No full textWe present results from a 100 ks XMM-Newton observation of the hot gas in the Virgo cluster elliptical galaxy NGC 4472. We find a surface brightness discontinuity ∼21 kpc north of the nucleus, consistent with being a contact discontinuity between two moving fluids. We also detect a >60 kpc long ram-pressure stripped tail. The pressure across the discontinuity implies an infall velocity, vinfall, of 1000 km s-1 < vinfall <2200 km s-1 depending on what assumptions are made about the density and pressure of the external gas. We suggest that the NGC 4472 group is falling into a collapsing filament, which is itself falling into the Virgo cluster. The gas of a collapsing filament is rapidly decelerated as it crosses the standoff shock, but the apparent high velocity of infall for NGC 4472 could be simply due to the fact that the gravitating potential of the NGC 4472 group is unaffected by this shock. While the group falls through the shock its gas will be stripped as it passes through the stalled gas of the filament. Additionally, we find two sets of cool filamentary arms to the east and the southwest of the nucleus. One of the southwest arms is coincident with a sharp filament seen with Chandra. We interpret these arms as filaments of cool gas that have been driven out from the center of the galaxy by the buoyant evolution of a radio bubble. The age of this outburst is ∼108 yr assuming that the buoyant bubble rises with a velocity of ∼0.4cs = 200 km s -1; the energy of the outburst is a modest ∼2 × 10 56 erg
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
NEW WESTERBORK OBSERVATIONS OF THE HI CLOUD NEAR NGC-4472
No full textThe H I gas which hes between the giant Virgo elliptical NGC 4472 and the gas-deficient dwarf irregular UGC 7636 has been observed at high resolution and sensitivity with the Westerbork radio telescope. It is a concentration of gas at a projected distance halfway between the two galaxies, and at an intermediate velocity. There is a possible second clump of emission which provides additional evidence of gas infall towards the nucleus of NGC 4472, perhaps related to the giant's double radio source. The entire system is embedded (in projection) in the X-ray halo of the elliptical
Linked collectors and determiners for: European Molecular Biology Laboratory Australian Mirror.
No full textNatural history specimen data linked to collectors and determiners held within, "European Molecular Biology Laboratory Australian Mirror". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/c1fc2df7-223b-4472-8998-70afb3b749ab">https://bionomia.net/dataset/c1fc2df7-223b-4472-8998-70afb3b749ab</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/c1fc2df7-223b-4472-8998-70afb3b749ab">https://gbif.org/dataset/c1fc2df7-223b-4472-8998-70afb3b749ab</a>. Formatted as a Frictionless Data package
A low dose of recombinant interleukin-1 protects granulocytopenic mice from lethal Gram-negative infection
No full textContains fulltext :
4472.pdf (Publisher’s version ) (Open Access
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