A. Antoniou

Similarity Between DACs/SACs Phenomena in Hot Emission Stars and Quasars Absorption Lines

In the spectra of Hot Emission Stars and AGNs we observe some peculiar profiles that result from dynamical processes such as accretion and/or ejection of matter from these objects. In this paper we indicate that DACs and SACs phenomena, can explain the spectral lines peculiarity in Hot Emission Stars and AGNs. We also try to connect the physical properties of absorption regions around stars and quasars.

The The structure of the Si IV region in Be stars: a study of Si IV spectral lines in Be 68 stars

Using the GR model, we analyze the UV Si IV resonance lines in the spectra of 68 Be stars of different spectral subtypes, in order to detect the structure of Si IV region. We calculated the values of the rotational, radial and random velocities as well as the absorbed energy of each one of the λλ 1393.755, 1402.778 A Si IV resonance lines and we present the relation between some of these parameters and their variation as a function of the spectral subtype.

A New Modeling Approach For DACs And SACs Regions In The Atmospheres Of Hot Emissions Stars

The presence of Discrete Absorption Components (DACs) or Satellite Absorption Components (SACs) is a very common phenomenon in the atmospheres of hot emission stars (Danezis et al. 2003, Lyratzi & Danezis 2004) and result to the complex line profiles of these stars. The shapes of these lines are interpreted by the existence of two or more independent layers of matter nearby a star. These structures are responsible for the formation of a series of satellite components for each spectral line. Here we will present a model reproducing the complex profile of the spectral lines of Oe and Be stars with DACs and SACs (Danezis et al. 2003, Lyratzi & Danezis 2004). In general, this model has a line function for the complex structure of the spectral lines with DACs or SACs and include a function L that considers the kinematic (geometry) of an independent region. In the calculation of the function L we have considered the rotational velocities of the independent regions, as well as the random velocities within them. ...

A Study of the Structure of Different Ionization Potential Regions in the Atmosphere of AX Mon (HD 45910)

The complex structure and the peculiar profiles of some spectral lines are common in the UV spectrum of AX Mon (HD 45910). The observed peculiar profiles are composed by a number of SACs or DACs. In this paper, using the GR model, we study the complex profile of the Al II (λ 1670.81 A), Al III (λλ 1854.722, 1867.782 A), Mg II (λλ 2795.523, 2802.698 A), Fe II (λ 2586.876 A), C II (λλ 1334.515, 1335.684 A) and Si IV (λλ 1393.73, 1402.73 A) spectral lines. Additionally, we calculate the relation of some kinematical parameters of the regions that create the DACs/SACs of the studied lines with the ionization potential.

Kinematics of Broad Absorption Line Regions of PG 1254+047

In this paper we study the Lyα spectral line and the N V, Si IV and C IV resonance lines in the UV spectrum of the Broad Absorption Line Quasar (BAL QSO) PG 1254+047. We found that the studied Broad Absorption Lines (BALs) of this quasar are created by a number of Satellite Absorption Components (SACs). We calculated some kinematical parameters such as the apparent rotational (Vrot) and radial (Vrad) velocities of the regions where the studied lines are created and the random velocities (Vrand) of the studied ions.

DACs and SACs in the UV Spectrum of the Quasar PG 0946+301

In this paper we study the C IV and Si IV resonance lines in the UV spectrum of the Broad Absorption Line Quasar (BAL QSO) PG 0946+301. The studied Broad Absorption Lines (BALs) are mainly created by a number of Satellite Absorption Components (SACs). However, the C IV doublet of PG 0946+301 is one of the very few lines that present clearly the DACs phenomenon, in the case of quasars. We applied the GR model and we calculated the apparent rotational (Vrot) and radial (Vrad) velocities of the regions where the studied lines are created and the random velocities (Vrand) of the C IV and Si IV ions.

Kinematical parameters in the coronal and post-coronal regions of the Oe stars

In this progress report we present the main results of our research. Using a new model we studied the kinematical parameters such as the random velocities of the ions, which create the spectral lines of C IV, N IV and N V in the spectra of 20 Oe stars, as well as the rotational and radial velocities of the regions, where the above ions are created. We calculated the values of the above parameters and we present the relations between them as well as their variation as function of the spectral subtype. We also present the random velocities of the ions for each one of the C IV, N IV and N V regions as a function of the photospheric rotational velocities. Finally, we propose an explanation for the large widths that we observe in the studied spectral lines, as these widths can not be explained as large rotational or random velocities.

Long Term Variability of the Radial Velocities in the Coronal and Post‐coronal Regions of the Oe Star HD 93521

We examine the timescale changes of C IV, N IV and N V spectral lines of the Oe star HD 93521, during a period of 16 years, applying the model proposed by Danezis et al. (2005). We found that the spectral lines consist of one or more Satellite Absorption Components (SACs or DACs) which construct the whole spectral profile. In this paper we present the time scale variation of the radial velocities.

A New Approach For The Structure Of Ha Regions In 120 Be‐type Stars

In this paper we present a statistical study of the Hα line profiles of 120 Be‐type stars using the model proposed by Danezis et al. (2003) and Lyratzi & Danezis (2004). This model proposes that the density layers which produce the Hα line lie in different regions in the stellar atmosphere. In the Be‐type stellar atmospheres, there are two regions that can produce the Hα satellite components. The first one lies in the chromosphere and the second one in the cool extended envelope. By fitting the Hα line profiles with the line function of the proposed model we are able to calculate: a) For the chromospheric absorption components we calculated the rotational and radial velocities as well as the optical depth. b) For the emission and absorption components which are created in the cool extended envelope we calculated the radial velocities, the FWHM and the optical depth. Finally, we present the relation between these parameters with the spectral subtype and the luminosity class.