arXiv subjects

Helene Di Nella

Publications and source records attributed to Helene Di Nella.

2 recordsLinked to original sources

arXiv1996

Are the Perseus-Pisces chain and the Pavo-Indus wall connected?

A significant empty region was found between the southern Pavo- Indus (PI) wall and the northern Perseus-Pisces (PP) chain. This survey tests the reality of this void which may simply reflect previous poor sampling of the galaxies in this region. Redshifts for a magnitude selected sample of 379 galaxies were obtained covering the four UKST/SERC survey fields with Bt <= 17.0. All redshifts were obtained with the FLAIR multi-object spectroscopy system on the 1.2 m U.K. Schmidt Telescope at Siding Spring, Australia. Two highly significant density enhancements were found in the galaxy distribution at 133 Mpc and 200 Mpc (Ho=75 km/s/Mpc). We claim that no connexion exists between PP and PI. However, a southern extension of PP was detected and makes the total length of this chain of more than 150 Mpc.

astro-ph↗

arXiv1995

Possible Connexion Between Large Scale Structures

From the Lyon-Meudon Extragalactic Database LEDA, we constructed a sample of 27,000 galaxies with radial velocities smaller than 15,000 km s$^{-1}$. From this first sample we selected the 5,683 largest galaxies which constitute a sample complete up to the diameter limit $D_{25}=1.6'$. This sub-sample has been used to search for the most populated plane. The result is that the plane defined by the pole ($l=52 °$; $b=16 °$) contains twice as many galaxies as would be found for randomly distributed galaxies. This plane is not far from the supergalactic plane. Then, the distribution of galaxies is studied in this plane by using the radial velocity as an estimate of the distance. An excess of galaxies appears at a distance of about 70 Mpc. We discuss the reality of this density enhancement which could result from selection effects.

astro-ph↗