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Astron. Astrophys. 330, 1136-1144 (1998)

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Solar mesogranule lifetime measurements

Th. Roudier 1, J.M. Malherbe 2, J. Vigneau 3 and B. Pfeiffer 3

1 Observatoire Midi-Pyrénées, UMR 5572 Pic du Midi, F-65201 Bagnères de Bigorre, France
2 Observatoire de Paris, Section de Meudon, URA 2080, DASOP, F-92195 Meudon, France
3 Observatoire Midi-Pyrénées, UMR 5572 Pic du Midi, F-31400 Toulouse, France

Received 30 April 1997 / Accepted 13 October 1997

Abstract

We present a study in which the solar lifetime of mesocells (4-10 arcsec) was determined from a long time sequence (6 h 40 min) obtained at the Pic du Midi Observatory. The mesocell detection was performed by local correlation tracking, using various spatial and temporal windows. The histograms derived from the visual measurements reveal that mesoscale lifetime is between 10 min and 160 min, with peaked distributions around 30-40 min. The indirect method for lifetime estimation using a correlation coefficient, gives a mesocale lifetime from 16 to 185 min depending on the temporal window and the methods used. The proper motions of the long-living mesocells are found to be random with respect to the superganule flows, with the peak distribution of horizontal velocities at 0.5 km/s. The results of this mesocell lifetime determination method are smaller by a factor of 2 to 5 with respect to the previous results. This difference could be attributed to the mesocell definition, the method of measurement or the different location of the mesocell field of view in the supergranular network.

Key words: Sun: photosphere – Sun: granulation – convection

Send offprint requests to: Th. Roudier

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© European Southern Observatory (ESO) 1998

Online publication: January 27, 1998
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