 | Shibu K. Mathew Professor
Udaipur Solar Observatory Rajasthan, INDIA E-mail: [email protected] Telephone: +91-0294-2457212 |
My current research interests include:
- Study of sunspot
- Umbral brightness variation with solar cycle
- Study of solar
active region magnetic field and it's evolution
- New Fabry-Perot etalon based imager for the MAST telescope
Sunspot contrast study is carried out using SoHO/MDI (Solar and Heliospheric Observatory/Michelson Doppler Imager)
continuum images. Dependence of umbral core brightness, the mean umbral brightness and penumbral brightness on
solar cycle is investigated using the above data. In future, multivariate analysis will be carried out to separate the
effects of umbral radius, heliocentric angle, and solar cycle phase on umbral brightness. Hinode SOT/SP data will also be used for
the study of spot size dependence on the minimum umbral contrast.
A new imager is being made at USO to be used as a back-end instrument for MAST telescope. The narrow band filter is constructed
using two tandem solid state Fabry-Perot etalons. The etalons are made of Lithium Niobate electro-optic crystal and can be
tuned to different wavelengths by applying high voltages.
Selected Publications:
- Rapid Formation and Disappearance of a Filament Barb
Joshi, A. D., Srivastava, N., Mathew, S. K., Martin, S. F., 2013, Solar Physics, 288, 191
- Formation of a penumbra in a decaying sunspot
Louis, R. E., Mathew, S. K., Puschmann, K. G., Beck, C., Balthasar, S., 2013, A&A, 552, 7
- Analysis of a Fragmenting Sunspot Using Hinode Observations
Louis, R. E., Ravindra, B., Mathew, S. K., Bellot Rubio R. L., Bayanna, A. R., Venkatakrishnan, P., 2012, ApJ, 755, 16
- Properties of Umbral Dots from Stray Light Corrected Hinode Filtergrams
Louis, R. E., Mathew, S. K.,
Bellot Rubio R. L., Ichimoto, K., Ravindra, B., Bayanna, A. R., 2011, ApJ, 752, 109
-
Issues with external occultation of a coronagraph
Bayanna, A. R., Mathew, S. K., Sankarasubramanian, K., Venkatakrishnan, P., Singh, J., Prasad, B. R., 2011, Expt. Astronomy, 29, 145
- Acoustic Power Absorption and its Relation to Vector Magnetic Field of a Sunspot
Gosain, S., Mathew, S. K.,
Venkatakrishnan, P., 2011, Solar Physics, 268, 335
- Supersonic Downflows at the Umbra-Penumbra Boundary of Sunspots
Louis, R. E., Bellot Rubio, L, R., Mathew, S. K.,
Venkatakrishnan, P., 2011, ApJ, 727, 49
- Automated Detection of Filaments and Their Disappearance Using
Full-Disc H-alpha Images
Joshi, A. D., Srivastava, N., Mathew, S. K., 2010,
Sol. Phys., 262, 425
- Supersonic downflows in a sunspot light bridge
Louis, R. E., Bellot Rubio, L. R., Mathew, S. K., Venkatakrishnan, P., 2009,
ApJ, 704, L29
- Stray light correction and contrast analysis of Hinode
broad-band images
Mathew, S. K., Zakharov, V., Solanki, S. K., 2009,
A&A, 501, L19.
- Source region of the 18 November 2003 coronal mass ejection that led to
the strongest magnetic storm of cycle 23
Srivastava, N., Mathew, S. K., Louis, R. E., Wiegelmann, T., 2009,
J. Geophys Res., 114, A03107.
- Dynamics of sunspot light bridges as revealed by high-resolution images from Hinode
Louis, R. E., Bayanna, R. A., Mathew, S. K., Venkatakrishnan, P., 2008,
Sol. Phys., 252, 43.
- Enhanced p-mode absorption seen near the sunspot umbral-penumbral boundary
Mathew, S. K., 2008,
Sol. Phys., 251, 515.
- Properties of sunpsots in cycle 23: I. Dependence of brightness
on sunspot size and cycle phase
Mathew, S. K., Martinez Pillet, V., Solanki, S. K., Krivova, N. A., 2007,
A&A, 465, 291.
- The Imaging MAgnetograph eXperiment for
SUNRISE balloon Antarctica project
Martinez Pillet, V., Bonet, J. A., Collados, M. V., Jochum, L., Mathew, S. K., et al., 2004, SPIE, 5487, 1152.
- On the fine structure of sunspot penumbrae. I. A quantitative
comparison of two semiempirical models with implications for the Evershed effect
Borrero, J. M., Solanki, S. K., Bellot Rubio, L. R., Lagg, A., Mathew, S. K., 2004, A&A, 422, 1093.
- Thermal-magnetic relation in a sunspot and a map of its Wilson
depression
Mathew, S. K., Solanki, S. K., Lagg, A., Collados, M., Borrero, J. M., Berdyugina, S., 2004, A&A, 422, 693.
- Three dimensional structure of a regular sunspot from the
inversion of IR Stokes profiles
Mathew, S. K., Lagg, A., Solanki, S. K., Collados, M., Borrero, J. M., Berdyugina, S., Krupp, N., Woch, J., Frutiger, C. 2003, A&A, 410, 695.
- Experimentally Determined r13 Electro-Optic Coefficient for a Lithium Niobate Crystal
Mathew, S. K., 2003, App. Opt., 42, 3580.
- Magnetic field gradient and flare: study of a small flare in NOAA 8038
Mathew, S. K., Ambastha, A., 2000, Sol. Phys., 197, 75.
- A Digital Imaging Multi-Slit Spectrograph for Measurement of Line-of-Sight Velocities on the sun
Srivastava, N., Mathew, S. K., 1999, Sol. Phys., 185, 61.
- Fabry-Perot filter based solar video
magnetograph
Mathew, S. K., Bhatnagar, A., Prasad, C. D., Ambastha, A., 1998, A&AS., 133, 285.
- Solar Photospheric and Chromospheric Observations using a Lithium-Niobate Fabry-Perot etalon
Debi Prasad, C., Mathew, S. K., Bhatnagar, A., Ambastha, A., 1998, Experimental Astronomy, 8, 125.
Miscellaneous: