Search results for "Spiral galaxy"

The Hamburg/ESO R-process Enhanced Star survey (HERES): Project Overview, and New r-II Stars

2005

Monitoring of the prompt radio emission from the unusual supernova 2004dj in NGC2403

2005

Supernova 2004dj in the nearby spiral galaxy NGC2403 was detected optically in July 2004. Peaking at a magnitude of 11.2, this is the brightest supernova detected for several years. Here we present Multi-Element Radio Linked Interferometer Network (MERLIN) observations of this source, made over a four month period, which give a position of R.A. = 07h37m17.044s, Dec =+65deg35'57.84" (J2000.0). We also present a well-sampled 5 GHz light curve covering the period from 5 August to 2 December 2004. With the exception of the unusual and very close SN 1987A, these observations represent the first detailed radio light curve for the prompt emission from a Type II-P supernova.

A Sample of Field Ellipticals

2003

Using well-defined selection criteria applied to the LEDA galaxy catalogue we have constructed a sample of elliptical galaxies that can be taken to lie in the field. Such criteria can easily be applied to theoretical simulations for direct comparison with observations. The variation of the number of `isolated' ellipticals with selection criteria is also investigated. A preliminary study of the environment of the field ellipticals shows that, in the mean, they are surrounded by a population of dwarf galaxies, out to projected radii of at least 500 kpc, with a radial density profile of $r^{-0.6\pm 0.2}$ and a luminosity function slope of $\alpha \sim -1.8$. The results are compared and contra…

Unveiling the environment and faint features of the isolated galaxy CIG 96 with deep optical and HI observations

2018

Context. Asymmetries in atomic hydrogen (HI) in galaxies are often caused by the interaction with close companions, making isolated galaxies an ideal framework to study secular evolution. The AMIGA project has demonstrated that isolated galaxies show the lowest level of asymmetry in their HI integrated profiles compared to even field galaxies, yet some present significant asymmetries. CIG 96 (NGC 864) is a representative case reaching a 16% level. Aims. Our aim is to investigate the HI asymmetries of the spiral galaxy CIG 96 and what processes have triggered the star-forming regions observed in the XUV pseudo-ring. Methods. We performed deep optical observations at CAHA1.23m, CAHA2.2m and V…

8.4GHz VLBI observations of SN2004et in NGC6946

2007

We report on 8.4GHz Very Long Baseline Interferometry (VLBI) observations of the type II-P supernova SN2004et in the spiral galaxy NGC 6946, made on 20 February 2005 (151 days after explosion). The Very Large Array (VLA) flux density was 1.23$\pm$0.07 mJy, corresponding to an isotropic luminosity at 8.4GHz of (4.45$\pm$0.3)$\times10^{25}$ erg s$^{-1}$ Hz$^{-1}$ and a brightness temperature of (1.3$\pm$0.3)$\times10^{8}$ K. We also provide an improved source position, accurate to about 0.5 mas in each coordinate. The VLBI image shows a clear asymmetry. From model fitting of the size of the radio emission, we estimate a minimum expansion velocity of 15,700$\pm$2,000 km s$^{-1}$. This velocity…