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Browsing by Author "Tripathy, S. C"

Browsing by Author "Tripathy, S. C"

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  • Effects on solar structure of opacity changes 
    Tripathy, S. C; Christensen-Dalsgaard, J (Astronomical Society of India, 1996)
    We investigate the sensitivity of solar structure to localized changes in opacity by considering differences between models computed with locally modified opacity and unmodified references models. The results confirm that ...
  • GONG p-mode frequency changes with solar activity 
    Bhatnagar, A; Jain, K; Tripathy, S. C (Astronomical Society of India, 2000)
    In this paper, we present a correlation study of nine solar activity indices with p-mode frequency shifts obtained from the GONG data. It is found that the two are closely correlated and a linear relationship exits. Further, ...
  • Horizontal flows in active regions from ring-diagram and local correlation tracking methods 
    Jain, K; Tripathy, S. C; Ravindra, B; Komm, R; Hill, F (IOP Publishing, 2016-01)
    Continuous high-cadence and high spatial resolution Dopplergrams allow us to study subsurface dynamics that may be further extended to explore precursors of visible solar activity on the surface. Since the p -mode ...
  • On the p-mode Asymmetry between Velocity and Intensity from the GONG+ Data 
    Tripathy, S. C; Jain, K; Hill, F; Toner, C. G (Astronomical Society of India, 2003)
    We have analyzed the local acoustic spectra of small regions over the solar surface at different locations from disk center to limb via the technique of ring diagrams. The analysis suggest that the frequency shifts between ...
  • On the power and frequency of p-modes in sunspots 
    Kumar, B; Tripathy, S. C; Jain, R; Deshpande, M. R (Astronomical Society of India, 2000)
    A time series of GONG Dopplergrams has been used to measure the velocity fluctuations in the sunspot and quiet photosphere simultaneously. The power spectrum analysis shows that the power of the predominant p-mode is reduced ...
  • A relation between frequency shift and the changes in activity indices 
    Jain, K; Tripathy, S. C; Kumar, B; Bhatnagar, A (Astronomical Society of India, 2000)
    We present a linear relation between the shift in p-mode frequencies and variation in two solar activity indices, namely the sunspot number and 10.7 cm radio flux. From this relation, an empirical model is constructed to ...
  • Solar Cycle Variation in GONG and MDI Data : 1995-2002 
    Tripathy, S. C (Astronomical Society of India, 2003)
    Both GONG and MDI projects have measured p-mode frequencies of the Sun for more than 7 years. Here we review what we have learnt from the temporal variation of the oscillation frequencie and splitting coefficients.
  • Solar rotation rate from minimum to maximum of activity cycle 
    Jain, K; Tripathy, S. C; Bhatnagar, A; Kumar, B (Astronomical Society of India, 2001)
    Using helioseismic data from SOI/MDI and GONG for the current solar cycle 23, from solar minimum to near maximum phase, we report here on the temporal variation of the rotation rate.
  • A study of acoustic halos in active region NOAA 11330 using multi-height SDO observations 
    Tripathy, S. C; Jain, K; Kholikov, S; Hill, F; Rajaguru, S. P; Cally, P. S (Elsevier B.V, 2018-01)
    We analyze data from the Helioseismic Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) instruments on board the Solar Dynamics Observatory (SDO) to characterize the spatio-temporal acoustic power distribution ...
  • Temporal variations of solar p-mode frequencies on time scales of 27 days 
    Tripathy, S. C; Jain, K; Bhatnagar, A (Astronomical Society of India, 2002-09)
    We have studied variations in the frequencies of intermediate degree solar oscillation modes on a time cadence of 18 and 27 days. We report that the p-modes adjust to changes in the activity measures on time scales as ...
  • Testing the helioseismic determination of opacity corrections 
    Tripathy, S. C; Christensen-Dalsgaard, J (Astronomical Society of India, 1998)
    We investigate the effect of localized opacity modifications on the sound-speed profile of solar models. The sound-speed difference between the Sun and a solar model is used to deduce the opacity correction that would be ...

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