Time-distance helioseismology
Article Abstract:
A new technique to study the interior of the sun is presented. The technique is based on the methods used to study the terrestrial interior by deriving time-distance values from earthquakes or man-made explosions. As applied on the sun, the events studied derive from acoustic sources whose probable origin is the turbulent convection just beneath the solar surface. The technique involves the measurement of times taken by acoustic waves to travel from the solar surface to the bottom of their cavity and back, as well as the distances, measured as an angle at the surface between surface reflections.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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Downflows under sunspots detected by helioseismic tomography
Article Abstract:
The Sun's surface is marked with areas of cooler gas and stronger magnetic fields that are known as sunspots. To understand how sunspots are formed and maintained, it was proposed that small vertical magnetic flux tubes that originate from deep within the Sun cause downflows to form around them once they emerge at the surface. The downflows bind some flux tubes together to form a sunspot, making them behave as one flux bundle. Through travel-time helioseismology, the presence of downflows beneath sunspots and plages is examined.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Ambient acoustic imaging in helioseismology
Article Abstract:
Helioseismological techniques have been developed that probe localized regions of the solar interior. Resulting information is based on physical quantities but does not provide detail of local subsurface inhomogeneities. A new method for building three-dimensional images has been developed, using acoustic noise in the Sun. The solar surface acts as a computational lens and acoustic waves are collected and summed in phase.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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