Rotational Effects on Supergranulation- A Survey

International Journal of Research and Scientific Innovation (IJRSI) | Volume IV, Issue X, October 2017 | ISSN 2321–2705 

Rotational Effects on Supergranulation- A Survey

Sowmya G M[1], Rajani G[1], Yamuna M[1], Paniveni Udayshankar[2], R Srikanth[3], Jagdev Singh[4]
[1]GSSS Institute of Engineering & Technology for Women, KRS Road, Meragalli Mysuru-570016, Karnataka, India
[2]Inter-University Centre for Astronomy and Astrophysics, Pune, India
[3]Poornaprajna Institute of Scientific Research, Devanahalli, Bangaluru-562110, Karnataka, India
[4]Indian Institute of Astrophysics, Koramangala, Bangalore, Karnataka, India

Abstract: – Supergranules are large-scale convection cells in the high solar photosphere that are seen at the surface of the Sun as a pattern of horizontal flows. They are approximately 30,000 kilometres in diameter and have a lifespan of about 24 hours. About 5000 of them are seen at any point of time in the upper photospheric region. A great deal of observational data and theoretical understanding is now available in the field of supergranulation. In this paper, we review the literature on the rotational effect of the supergranules and its relation to the solar dynamo model.

Key words: supergranulation, sunspot, helosismology, magnetic field

I. INTRODUCTION

The Sun, situated at the centre of the solar system, is the closest star to the earth. The light from the Sun heats our planet and makes life possible. The visible solar atmosphere consists of three regions, the photosphere, the chromosphere and the solar corona. Most of the visible light comes from the photosphere. The surface of the Sun, the photosphere, is beset with a cellular pattern caused by the convective flow of heat rising from the solar interior. Convection is the chief mode of transport in the outer layers of all cool stars such as the Sun (Noyes, 1982). The convection zone, which has a thickness 30% of the solar radius, lies in the sub-photospheric layers of the Sun. Convection is revealed on four scales, namely, granulation, with a typical size of 1000 km; mesogranulation, with typical size of 10000 km; supergranulation, with a typical size of 30,000 km; and giant granules, with typical size of 108 Mm.

Granulation – About 2 million granules are found at any point of time on the solar surface. They are columns of hot gases rising from below the photosphere with a velocity of about 1- 2 km/sec. Each granule persists for about 8 minutes.

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