P. N. Okeke

University of Nigeria

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J. O. Urama

University of Nigeria

Bonaventure Okere

University of Nigeria

S. E. Okoye

University of Nigeria

M. W. Anyakoha

University of Nigeria

F. N. Ndili

University of Houston

C.N. Ofodum

National Space Research and Development Agency

I. E. Ekejiuba

Modibbo Adama University of Technology

A. A. Ubachukwu

University of Nigeria

Daniel Okoh

National Space Research and Development Agency

A. E. Chukwude

University of Nigeria

Cooperative Institutions

University of Nigeria

National Space Research and Development Agency

Astronomical Observatory

South African Radio Astronomy Observatory

University of Cape Town

Xinjiang Astronomical Observatory

Hartebeesthoek Radio Astronomy Observatory

Nnamdi Azikiwe University

Center for Astrophysics Harvard & Smithsonian

Harvard University

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H2CO Observations Towards CH3OH Maser Sources

Proceedings of the International Astronomical Union (2012)

Daniel Okoh Jarken Esimbek Jianjun Zhou Xindi Tang A. E. Chukwude

Abstract Formaldehyde (H 2 CO) is an accurate probe of physical conditions in dense and low-temperature molecular clouds towards massive star formation regions, while 6.7 GHz methanol (CH 3 OH) masers provide ideal sites to probe the earliest stages of massive stellar formation. We present preliminary results of our investigation into the possible relationship between formaldehyde and methanol astrophysical masers with the view to expanding knowledge on massive star formation processes. Observations are done using the Nanshan 25m radio telescope of the Xinjiang Astronomical Observatories, Urumqi, China. 127 Methanol sources (from the work of Green et al . 2010, Xu et al . 2003, Pestalozzi et al . 2005, and Xu et al . 2009) have been observed so far for 4.8 GHz formaldehyde absorption lines, and H 2 CO signals have been detected in 86 of them, 31 of which are newly discovered. We obtained good correlation (0.85 correlation coefficient) between the velocities of the sources, and a poor correlation (−0.03 correlation coefficient) between their intensities, an indication that signals from the two lines originate from about the same region, but that the excitation mechanisms that drive them are likely different.

Molecular absorption

10.1017/s1743921313000719

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Citations (1)

On the recent detection of new oscillations in rapidly oscillating Ap star HD 137949 - 1st result

New Astronomy (2018)

C.N. Ofodum P. N. Okeke

Oscillation (cell signaling)

Frequency analysis

10.1016/j.newast.2018.06.005

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Citations (4)

Algebraic constraints for higgs multiplets

International Journal of Theoretical Physics (1975)

F. N. Ndili P. N. Okeke

10.1007/bf01807764

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Citations (1)

Proton-Proton Collisions in Extragalactic Radio Sources

Symposium - International Astronomical Union (1982)

S. E. Okoye P. N. Okeke

The majority of extragalactic radio sources are known to consist of two extended components straddling an optical galaxy or quasar with each component being maintained from the nucleus of the associated optical object through a beam or jet of relativistic plasma and magnetic fields. Hitherto, the energetics of radio source components have been considered essentially from the point of view of the cooling of the relativistic electrons through their interaction with ambient magnetic fields (synchrotron radiation) and with low energy photons (inverse Compton emission). Here we consider a hitherto neglected problem involving the mutual interactions between the fast particles themselves. (The results of a detailed investigation into these interactions will be reported elsewhere — see Okoye and Okeke, 1982.)

Astrophysical jet

Relativistic plasma

10.1017/s0074180900027376

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Citations (3)

Evaluation of Ambient Noise Levels in Port Harcourt Metropolis, South-South, Nigeria

Figshare (2015)

Iosr Journals P. N. Okeke D. M. C George

Port harcourt

Port (circuit theory)

10.6084/m9.figshare.1491329.v1

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Radiowave propagation measurements in Nigeria (preliminary reports)

Theoretical and Applied Climatology (2012)

S. E. Falodun P. N. Okeke

International conferences on frequency coordination have, in recent years, required new information on radiowave propagation in tropical regions and, in particular, on propagation in Africa. The International Telecommunications Union (ITU-R) initiated 'radio-wave propagation measurement campaign' in some African countries some years back. However, none of the ITU-initiated experiments were mounted in Nigeria, and hence, there is lack of adequate understanding of the propagation mechanisms associated with this region of the tropics. The Centre for Basic Space Science (CBSS) of NASRDA has therefore embarked on propagation data collection from the different climatic zones of Nigeria (namely Coastal, Guinea Savannah, Midland, and Sahelian) with the aim of making propagation data available to the ITU, for design and prediction purposes in order to ensure a qualitative and effective communication system in Nigeria. This paper focuses on the current status of propagation data from Nigeria (collected by CBSS), identifying other parameters that still need to be obtained. The centre has deployed weather stations to different locations in the country for refractivity measurements in clear atmosphere, at the ground surface and at an altitude of 100 m, being the average height of communication mast in Nigeria. Other equipments deployed are Micro Rain Radar and Nigerian Environmental and Climatic Observing Program equipments. Some of the locations of the measurement stations are Nsukka (7.4° E, 6.9° N), Akure (5.12° E, 7.15° N), Minna (6.5° E, 9.6° N), Sokoto (5.25° E, 13.08° N), Jos (8.9° E, 9.86° N), and Lagos (3.35° E, 6.6° N). The results obtained from the data analysis have shown that the refractivity values vary with climatic zones and seasons of the year. Also, the occurrence probability of abnormal propagation events, such as super refraction, sub-refraction, and ducting, depends on the location as well as the local time. We have also attempted to identify and calculate the most important propagation factors and associated data, such as k factor, that are relevant in considerations of propagation in tropical regions like Nigeria.

Atmospheric duct

10.1007/s00704-012-0766-z

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Citations (23)

Model of gamma-ray emission from large-scale jets

AIP conference proceedings (1988)

M. W. Anyakoha P. N. Okeke S. E. Okye

A model for gamma‐ray emission from large‐scale jets of quasars and active galactic nuclei is proposed. It is shown that if ∼107–1010 M⊙ of ambient matter is entrained by the jets in their interaction with the interstellar medium, the π° decay arising from proton collisions can constitute a observable source of gamma ray photons from the jet regions. A relativistic proton spectrum from the black hole, with spectral index between 2 and 2.66 can lead to gamma ray flux densities of the right order of magnitude expected from large scale jets.

Spectral index

10.1063/1.37231

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EUVE J1429-38.0: an eclipsing polar.

MNSSA (1997)

R. S. Stobie D. Buckley P. N. Okeke D. O’Donoghue

Source

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Implications of CP violation in hyperon decays

Astrophysics and Space Science (1992)