Nedelia Antonia Popescu

SED, Galactic Evolutionary Tracks and High‐z Galaxies

Using photometric redshifts determined by means of a neural network method, we investigate HDFN, HDFS, and CHANDRA samples (z < 6) in order to derive observational galactic evolutionary tracks in color — photometric redshift diagrams. We also present the behaviour of different high‐z galactic populations and theoretical N‐body VIRGO high‐z halos populations (GIF Project, semi‐analytic photometrical SED models using total and bulge component luminosities) in comparison with such galactic evolutionary tracks.

Romanian Contributions to the International Heliophysical Year

We present the Romanian activities within the framework of the International Heliophysical Year. All part of IHY aspects will be approached: history, science, education and outreach. In the history aspect, we emphasize the beginning of solar and artificial satellite researches in Romania. As symmetry over times, after fifty years, the solar group started a new phase in its development and research themes, a fact that constituted itself in a challenge for educational programs and new scientific projects. A very important part of our activity during the International Heliophysical Year was the outreach.

Galaxy Pairs and Groups in the AGNs’ Environments

Galaxy interactions can produce changes in galaxy morphology, induce star formation, and trigger active galactic nuclei (AGN). Most AGNs tend to occur in pairs or groups that exhibit signs of interaction between the components, resulting in peculiarities in their morphological structure and physical properties. Combining optical‐NIR photometric data, HST/WFPC2 morphological data and HST/WFPC2 archival images for galaxies in the environments of two AGN at z∼1, we carry out a morphological and photometric study of elliptical galaxies and disk galaxies properties, at different stages of interaction. The goal of this study is to analyze the effects of interactions on color and morphology of galaxy pairs, especially for disk galaxy pairs and mixed morphology pairs.

Extremely Red Galaxies in the Envinronments of AGNs at 0.5 < z < 1.5

By means of different color‐color criteria, resulted from PEGASE spectrophotometric evolution model for galaxies, rich samples of Extremely Red Galaxies (ERGs) are determined in the Held of 5 AGNs at 0.5 < z < 1.5. Optical‐NIR data are combined with HST morphological data in order to discriminate between the two main classes of galaxies that form the ERGs: old, passively evolving ellipticals and dusty star‐forming galaxies. The surface density, radial density profiles and color distributions for different populations of galaxies are determined. The presence of red galaxy overdensities in the fields of 3C 34, 3C 210 and B2 1335+28 is revealed.

A CME‐ICME study using data from SOHO and Ulysses

We analyze the solar source of a CME occurred on 2 March 2002, the follow up of its travel through the interplanetary space and the characteristics of the ICME registered by Ulysses satellite.

Study of Three ICMEs Events Registered by Ulysses in 2001

In‐situ data measured by Ulysses—SWOOPS, SWICS and VHM instruments—are used for the study of magnetic field and solar wind plasma parameters for the year 2001, in an attempt of founding new ICMEs based on the combination of classical identification conditions, plasma dynamics signatures, and plasma composition signatures. Three new candidates are determined for the DOY 80.3–81.6, DOY 155.18–156.3, and DOY 161.2–162.8. We track back to the Sun these events and determine their possible solar sources.

Multi-scale Modeling of the Interplanetary Magnetic Field

Models for heavy-tailed data with applications to the study of multi-scale behaviour of the interplanetary magnetic field are presented. Numerical aspects are given in the case of the data obtained by Ulysses mission (magnetometer VHM/FGM). This approach yields probabilistic predictions of the dynamics and multiscale behaviour of the interplanetary magnetic field.

A CME Sequence Investigation, August 14‐15, 2001

We investigate current models of ICMEs propagation (kinematics inside 1 AU) in terms of arrival time forecasts. We also try to evaluate the ability to trace individual ICME from Sun to 1 AU mainly dealing with superposition of closed sequential events.

Models for Heavy Tailed Data and Applications

An important topic in space research is represented by the study of statistical properties of the interplanetary magnetic field fluctuations, these being closely related to acceleration processes and energy transport in the solar wind. Analysis of the probability distribution functions of the velocity and magnetic field fluctuations has underlined their non‐Gaussian properties on small time scales, and uncorrelated features at large scale. In this paper, numerical solutions of space‐time fractional diffusion equations are used to analyze the presence or absence of heavy tails typically associated with multiscale behavior, in the case of the interplanetary magnetic field data obtained by Ulysses mission.

Interactions effects on color and morphology of galaxy pairs

Properties of galaxy pairs, such as color and morphology, are analyzed with respect to the samples of galaxies in the field of the radio galaxies 3C 220.1 (z = 0.62) and 3C 34 (z = 0.689), covering a total field of 12.4 arcmin2. Many galaxies present evident signs of interactions, with features of morphological disturbance and bluer optical‐NIR colors, suggesting that close interactions and mergers induce star‐forming episodes. The presence of many elliptical galaxies interacting in dry mergers is also distinguished in both samples of galaxy pairs.