Open Access Short Research Article

Phenomenology of Astrophysical Jets and Quasar/Galaxy Unification

O. L. Ubah, J. C. Ezeugo

International Astronomy and Astrophysics Research Journal, Page 7-12

Statistical and analytical methods have been used in this work to explain some physical phenomena that occur in extragalactic radio jets. Linear regression analyses were carried out among all the source observable parameters in our sample. The sample contains radio loud quasars and radio galaxies. Results of these analyses suggestively indicates that: (1) the physical phenomena which underscore the mechanisms of evolution of these extragalactic radio sources, and which manifest in their radio jet propagation have comparable origins; (2) the propagation of an extragalactic radio jet may depend on the following factors: (i) source energy density, (ii) jet solid angle, (iii) scale factor of the universe, (iv) angular size of the source, (v) density parameter, and (vi) ambient gas particle number density; (3) jet velocity scales as the square root of source energy density and inverse square root of source ambient medium density; (4) radio loud quasars and their galaxy counterparts are similar sources probably seen from different angles of observations. This supports Quasar/Galaxy Unification scheme. In this scheme, the two sub-classes of objects are expected to differ only in their aspect-dependent properties if orientation effects are the major factors that determine their different observed physical features.

Open Access Original Research Article

On Compact Steep Spectrum Radio Quasars/Galaxies and Youth Scenario

Ezeugo Jeremiah Chukwuemerie

International Astronomy and Astrophysics Research Journal, Page 1-6

Statistical methods of analyses have been used to find some difference in some parametric relationships in the two subclasses of compact steep spectrum (CSS) sources. These sub-classes include CSS quasars and CSS galaxies. This is done by carrying out linear regression analyses on the observed source linear sizes  against their respective observed redshifts  – the analyses are carried out individually for the quasars and the galaxies. Moreover, similar regression analyses are carried out on the observed source linear sizes against their respective observed luminosities . For the CSS quasars, result indicates that observed linear size shows an inverse relationship with observed redshift; while for the CSS galaxies, the converse is the case. On the linear size/luminosity plane, similar trends respectively for the CSS quasars and CSS galaxies are obtained. That is, for the quasars result shows an inverse relationship between linear size and luminosity; while for the galaxies, the relationship between the two observable parameters is a direct one. The  data show that CSS quasars evolve both in size and radiated power output with time; while for the galaxies the opposite is the case.  These results suggestively indicate that at earlier epoch, CSS galaxies appear more extended in sizes and radiated power than the CSS quasars. Therefore, in conclusion, we may state that in addition to supporting Youth Scenario (i.e. young sources evolving in dense ambient media), dynamical evolution of CSS galaxies is different from that of quasars – while CSS quasars evolve dynamically and progressively as well, CSS galaxies suffer retrogressive dynamical evolution.

Open Access Original Research Article

On the Central Engine of the Compact Steep Spectrum Source and Source Phenomena

Ezeugo, Jeremiah Chukwuemerie

International Astronomy and Astrophysics Research Journal, Page 13-18

In this paper, with some plausible assumptions we use analytical methods and statistical methods to show that the central engine (which presumably houses a super massive blackhole) of a typical compact steep spectrum source fuels the source observed physical phenomena. With analytical methods, we show that the power of the source central engine Capture1.PNG relates with some source observable parameters according to the relation, Capture.PNG  (where is mass of hydrogen nucleus,  is speed of light,  is jet opening solid angle,  is conversion efficiency of matter into radiation,  is source linear size,  is source luminosity, is jet internal pressure, and Q  is a constant). The indices,  and , are to be estimated. In order to semi-empirically obtain estimates of the values of the indices, we carry out linear regression analysis of source linear sizes (D) against their corresponding luminosities (P) . Results show that Capture3.PNG , while ψ = 32 is a positive integer. Hence, the aforementioned relation may be re-written as Capture2.PNG. This expression may be interpreted to mean that if some external factors are held fixed, the source central engine fuels/powers the observed physical properties/phenomena of the CSS source.

Open Access Original Research Article

Teaching Seasons with a Hands-on Activity

Michel Corci Batista, Oscar Rodrigues dos Santos, Veridiane Cristina Matins, Taisy Fernandes Vieira

International Astronomy and Astrophysics Research Journal, Page 19-35

A simple experiment built by the students can be used to investigate the seasons at different latitudes. With the help of the experimental apparatus, phenomena such as the midnight sun, the apparent motion of the sun, and the influence of the tilt of the earth's axis can be easily explained. In addition, the equatorial region has a warmer climate, while temperatures near the poles are more severe. In order to contribute to the teaching of astronomy in elementary education, this work aimed at developing an auxiliary material for science and physics teachers, using simple but correct language and easy to consult, and at evaluating its pedagogical potential. The first has a quantitative approach, for which an experiment was conducted comparing the performance of elementary school students on an assessment instrument consisting of 29 questions about physics and astronomy, before and after the introduction of the interdisciplinary notebook for practical activities in astronomy. The second phase has a qualitative approach of descriptive type, for which we used the field diary prepared by the researching teacher during the implementation of the activities, as well as the documents prepared by the students as a data collection tool. The results of the first phase were organized using the paired parametric t-test. The choice of this test accounts for the intra-individual dependence of the observations. In general, our results show a build-up of practical and dynamic thinking that motivates students to be interested in astronomy and, most importantly, a change in the attitude of the teacher-researcher in front of the classroom. We believe that the implemented material has a great pedagogical potential, with a motivational and reflective character.

Open Access Original Research Article

Gravity Model of Black Holes and Solar Planets

Faical Ramdani

International Astronomy and Astrophysics Research Journal, Page 36-42

By considering that gravity changes at increased elevation contribute to change in velocity we can obtain timescale variation related gravity as alternative to time dilation related space-time curvature. Gravity changes around planets and black holes are revisited by introducing a gravitosphere model where gravity works inside and around planets. Resulting gravitospheres related to planets and black holes radius shows evidence for a critical Radius of a star to develop black hole structure. Internal structure based gravity and velocity variations of black holes is suggested by including captured asteroids input which results in phase transformations and release of kinetic energy. These processes may explain vibrations related radiations, an adapted volcanic style with possible escape of particles and gravitational waves from horizon zone. By assuming that gravity control velocity changes and related structures it will provide the first elements of a universal gravity model.