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Javaraiah, J.; Gokhale, M. H.

doi:10.1023/a:1004928020737

Cited by 64 publications

(44 citation statements)

References 21 publications

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“…In fact the sunspots are also very good indicators that yield the dynamics of the convective envelope. Very recent studies (Javaraiah & Gokhale 1997;Javaraiah 2001;Hiremath 2002;Sivaraman et al 2003) show that variation of initial rotation rates derived from the daily motions of the sunspot groups with respect to their life spans is almost similar to the radial variation of internal rotation profile of the solar plasma.…”

Section: Conclusion and Discussionmentioning

confidence: 93%

The flares associated with the abnormal rotation rates of the bipolar sunspots: Reconnection probably below the surface

Hiremath

Suryanarayana

2003

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Abstract.We use the observations of Kodaikanal observatory white light pictures to study the association between the rotation rates of the bipolar sunspots and triggering of the flares. For the years 1969−1974, we compute daily rotation rates of the leading and the following spots of the bipolar sunspot groups during their life span. We find that either leading or following or both of the bipolar spot groups which have abnormal rotation rates during the course of their evolution are strongly associated with the occurrence of flares in the later stage of their life span. Other important findings are: (i) the abnormal rotation rates and the flares occur during the 50−80% of their life span of the spot group and, (ii) abnormal rotation rate of about 2• /day is required for triggering the flares. The strong relation between the occurrence of abnormal rotation rates of the sunspot groups and the occurrence of the flares enabled us to estimate the probable region of depth of reconnection below the solar surface.

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Section: Conclusion and Discussionmentioning

confidence: 93%

The flares associated with the abnormal rotation rates of the bipolar sunspots: Reconnection probably below the surface

Hiremath

Suryanarayana

2003

A&A

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“…However, it is quite unlikely that they could be anchored that deep. Indeed, recent results by Hiremath (2004) and Javaraiah & Gokhale (1997) show that old spots always rotates in such a way that they are likely to be anchored above that turning point. Furthermore, it is likely that the rotation rates observed in this paper are related to supergranular flows, since the formation of network structures is associated with strong downflows on the edges of supergranules.…”

Section: Discussionmentioning

confidence: 96%

“…The opposite approach can now be used, such that it is possible to try to determine the anchoring depth of magnetic features from their rotation rate. Javaraiah & Gokhale (1997), Hiremath (2002), and Sivaraman & Gokhale (2004) have thus used the internal rotation inferred by helioseismology to determine the anchoring depth of spots during their lifetimes. However, this interpretation of the different rotation rates of magnetic structures by their anchoring in the convection zone has never been completely analyzed, especially using large data sets and several dynamical variables.…”

Section: Introductionmentioning

confidence: 99%

Magnetic network dynamics: Activity level, feature size and anchoring depth

Meunier¹

2005

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Abstract.A large data set of MDI magnetograms is studied in order to analyze the global dynamics of magnetic structures from network to active regions. Two complementary techniques are used: feature tracking and correlation tracking. The very large data set allows the variation of their dynamics (angular rotation velocity and meridional circulation) to be studied in detail. Variation both in the dynamics as a function of size and distance to active regions (for feature tracking) and as a function of activity level in the correlation box are studied. These new results allow the possible anchoring depth of these magnetic features to be constrained. The observations of the magnetic network dynamics are not consistent with the dynamics deduced from helioseismology. So, some additional processes must be acting on the magnetic network in order to explain their global dynamics.

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“…Wilson magnetograph data during the period 1967 to mid-1980 and found that the rate at which the magnetic flux appears on the Sun is sufficient to create all the flux that is seen at the solar surface within a period of about 10 days. The magnetic structures of the sunspot groups may rise from near the bottom of the convention zone to the surface in about 10 days (Javaraiah & Gokhale 1997).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Solar cycle variations in the growth and decay of sunspot groups

Javaraiah

2011

Astrophys Space Sci

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We analysed the combined Greenwich (1874Greenwich ( -1976 and Solar Optical Observatories Network (1977-2011) data on sunspot groups. The daily rate of change of the area of a spot group is computed using the differences between the epochs of the spot group observation on any two consecutive days during its life-time and between the corrected whole spot areas of the spot group at these epochs. Positive/negative value of the daily rate of change of the area of a spot group represents the growth/decay rate of the spot group. We found that the total amounts of growth and decay of spot groups whose life times ≥ 2 days in a given time interval (say one-year) well correlate to the amount of activity in the same interval. We have also found that there exists a reasonably good correlation and an approximate linear relationship between the logarithmic values of the decay rate and area of the spot group at the first day of the corresponding consecutive days, largely suggesting that a large/small area (magnetic flux) decreases in a faster/slower rate. There exists a long-term variation (about 90-year) in the slope of the linear relationship. The solar cycle variation in the decay of spot groups may have a strong relationship with the corresponding variations in solar energetic phenomena such as solar flare activity. The decay of spot groups may also substantially contribute to the coherence relationship between the total solar irradiance and the solar activity variations.

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Cited by 64 publications

References 21 publications

The flares associated with the abnormal rotation rates of the bipolar sunspots: Reconnection probably below the surface

The flares associated with the abnormal rotation rates of the bipolar sunspots: Reconnection probably below the surface

Magnetic network dynamics: Activity level, feature size and anchoring depth

Solar cycle variations in the growth and decay of sunspot groups

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