Astrophysics Research Group

Meerut, India

Astrophysics Research Group

Meerut, India
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Mittal N.,H+ Technology | Sharma J.,Astrophysics Research Group | Verma V.K.,Uttarakhand Space Application Center | Garg V.,MM College
New Astronomy | Year: 2016

We have studied the characteristics of radio-loud (RL) and radio-quiet (RQ) front side halo coronal mass ejections (HCMEs) (angular width 360°) observed between the time period years 1996-2014. RL-HCMEs are associated with type II radio bursts, while RQ-HCMEs are not associated with type II radio bursts. CMEs near the Sun in the interplanetary medium associated with radio bursts also affect the magnetosphere. The type II radio burst data was observed by WIND/WAVES instrument and HCMEs were observed by LASCO/ SOHO instruments. In our study, we have examined the properties of RL-HCMEs and RQ-HCMEs and found that RL-HCMEs follow the solar cycle variation. Our study also shows that the 26% of slow speed HCMEs and 82% of fast speed HCMEs are RL. The average speed of RL-HCMEs and RQ-HCMEs are 1370 km/s and 727 km/s, respectively. Most of the RQ-HCMEs occur around the solar disc center while most of RL-HCMEs are uniformly distributed across the solar disc. The mean value of acceleration of RL-HCMEs is more than twice that of RQ-HCMEs and mean value of deceleration of RL- HCMEs is very small compare to RQ-HCMEs events. It is also found that RQ-HCMEs events are associated with C- and M-class of SXR flares, while RL-HCMEs events are associated with M and X-class of SXR flares, which indicates that the RQ-HCMEs are less energetic than the RL-HCMEs. We have also discussed the various results obtained in present investigation in view of recent scenario of solar physics. © 2016 Elsevier B.V. All rights reserved.

Mittal N.,H+ Technology | Mittal N.,Astrophysics Research Group | Sharma J.,Astrophysics Research Group | Garg V.,MM College
Acta Astronautica | Year: 2015

In this paper we have made a comprehensive statistical study on the Coronal Mass Ejections (CMEs) associated with Prominence Eruptions (PEs). A total number of 576 Prominence Eruptions observed by Nobeyama Radioheliograph during the period January, 1996 to December, 2013. We have studied the distribution of Coronal Mass Ejections speed, angular width and acceleration for Prominence Eruptions associated Coronal Mass Ejections. The median (average) linear speed is 492 (521) km/s. The mean angular width is 77°. The speed of Prominence Eruptions varies from few km/s to 400 km/s with the average value 89 km/s. Majority of Prominence Eruptions associate Coronal Mass Ejections are accelerating. On studying the speed-acceleration correlation for these events, we found that there is no correlation between them. The number variation during solar cycle of prominence activities is similar to that of sunspots. The fraction of Prominence Eruptions associated Coronal Mass Ejections during the solar minimum is less than that during solar maximum. We have also studied the mass, energy and latitudinal distribution of Prominence Eruptions associated Coronal Mass Ejections. © 2015I AA. Published by Elsevier Ltd. All rights reserved.

Mittal N.,Astrophysics Research Group | Mittal N.,Inter-University Center for Astronomy and Astrophysics | Narain U.,Astrophysics Research Group | Narain U.,Inter-University Center for Astronomy and Astrophysics
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2010

Solar coronal mass ejections (CMEs) are a striking manifestation of solar activity seen in the solar corona, which bring out coronal plasma as well as magnetic flux into the interplanetary space and may cause strong interplanetary disturbances and geomagnetic storms. Understanding the initiation of CMEs and forecasting them are an important topic in both solar physics and geophysics. In this paper, we review recent progresses in research on the initiation of CMEs. Several initiation mechanisms and models are discussed. No single model/simulation is able to explain all the observations available to date, even for a single event. © 2010 Elsevier Ltd.

Mittal N.,Astrophysics Research Group | Mittal N.,Krishna Institute of Management and Technology
Proceedings of the International Astronomical Union | Year: 2010

Solar prominences can be viewed as pre-eruptive states of coronal mass ejections (CMEs). Eruptive prominences are the phenomena most related to CMEs observed in the lower layers of the solar atmosphere. We have made a comprehensive statistical study on the CMEs associated with prominence eruptions. We have examined the distribution of CMEs speed and acceleration for prominence eruptions associated CMEs. We also examine the speed-acceleration correlation for these events and there is no correlation between speed and acceleration. The mean angular width is almost similar to normal CMEs. The number variation during solar cycle of prominence activities is similar to the sunspot cycle. © 2011 International Astronomical Union.

Pierantoni G.,Trinity College Dublin | Carley E.,Astrophysics Research Group
Proceedings - 6th International Workshop on Science Gateways, IWSG 2014 | Year: 2014

Heliophysics is a relatively new branch of physicsthat investigates the relationship between the Sun and the other bodies of the solar system. To investigate such relationships, heliophysicists can rely on various tools developed by the community. Some of these tools are on-line catalogues that list events(such as Coronal Mass Ejections, CMEs) and their characteristics as they were observed on the surface of the Sun or on the other bodies of the Solar System. Other tools offer on-line data analysis and access to images and data catalogues. During their research, heliophysicists often perform investigations that need to coordinate several of these services and to repeat these complex operations until the phenomena under investigation are fully analyzed. Heliophysicists combine the results of these services, this service orchestration is best suited for workflows. This approach has been investigated in the HELIO project. The HELIO project developed an infrastructure for a Virtual Observatory for Heliophysics and implemented service orchestration using TAVERNA workflows. HELIO developed a set of workflows that proved to be useful but lacked flexibility and re-usability. The TAVERNA workflows also needed to be executed directly in TAVERNA workbench, and this forced all users to learn how to use the workbench. Within the SCI-BUS and ER-FLOW projects, we have started an effort to re-think and re-design the heliophysics workflows with the aim of fostering re-usability and ease of use. We base our approach on two key concepts, that of meta-workflows and that of workflow interoperability. We have divided the produced workflows in three different layers. The first layer is Basic Workflows, developed both in the TAVERNA and WS-PGRADE languages. They are building blocks that users compose to address their scientific challenges. They implement well-defined Use Cases that usually involve only one service. The second layer is Science Workflows usually developed in TAVERNA. They implement Science Cases (the definition of a scientific challenge) by composing different Basic Workflows. The third and last layer, Iterative Science Workflows, is developed in WSPGRADE. It executes sub-workflows (either Basic or Science Workflows) as parameter sweep jobs to investigate Science Cases on large multiple data sets. So far, this approach has proven fruitful for three Science Cases of which one has been completed and two are still being tested. © 2014 IEEE.

Gupta P.,Astrophysics Research Group | Gupta M.,k-Technology | Yadav R.,Astrophysics Research Group | Narain U.,Astrophysics Research Group
Astrophysics and Space Science | Year: 2014

This work includes a study of some properties such as speed, apparent width, acceleration and latitudes, etc. of all types of Prominence Eruptions (PEs) and the associated Coronal Mass Ejections (CMEs) observed during the period of 1997-2006 by Nobeyama Radioheliograph (NORH) and SOHO/LASCO covering the solar cycle 23. The average speed of prominences and associated CMEs are 51 km/sec and 559 km/sec, respectively. The average angular width is 32{ring operator} and 74{ring operator}, respectively. As expected the associated CMEs are relatively faster and wider than the prominences. © 2014 Springer Science+Business Media Dordrecht.

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