About Me

I am a Senior Research Fellow at Indian Institute of Astrophysics, Bangalore and Aryabhatta Research Institute of Observational Sciences, Nainital. Solar Astrophysics is my primary area of research. I work on understanding solar activity (solar cycle), which help us to predict the future of our nearest and life-giving star, the Sun.

I also love to capture the reality that simply may not exist; I mean, I love to take photographs. One of my favourite quotes about photography is I really believe there are things nobody would see if I didn't photograph them" by Lewis Hine.

Contact Details

Bibhuti Kumar Jha
ARIES Observatory
Nainital-263001, Uttarakhand, India



Theoretical Model of the Near-Surface Shear Layer of the Sun

Monthly Notices of the Royal Astronomical Society. (2021)

In this study, we have used the thermal wind balance equation which actually tells about how the slight difference in temperature between solar poles and equator, which is called thermal wind term, is balanced by the centrifugal force appearing due to solar differential rotation. Most scientists believe that this condition is true only in the interior of the Sun and it does not hold near the solar surface. In this work, we have shown that this belief actually holds near the surface as well. We have noted that if this condition is true near the solar surface it can explain the existence of NSSL which is inferred in helioseismology based observation.

Measurements of Solar Differential Rotation Using the Century Long Kodaikanal Sunspot Data

Solar Physics 296:25 (2021)

In this work, we have studied the solar rotation by tracing sun spots from century-old digitalized films and photographs. The old films and photographs were taken at the Kodaikanal Solar Observatory (KoSO) of Indian Institute of Astrophysics (IIA). We compared the consistent digitized data with manual data of rotation taken earlier and able to differentiate the behaviors of the bigger and smaller solar spots for the first time. Such digitized data and differentiation of bigger and smaller sun spots can improve understanding of solar magnetism and sun spots, paving the path towards predicting solar cycles in the future.

Magnetic Field Dependence of Bipolar Magnetic Region Tilts on the Sun: Indication of Tilt Quenching

The Astrophysical Journal Letters 889 L19 (2020)

Magnetic-field dependence of active regions’ tilt angles are studied using the MDI/SOHO and HMI/SDO data for Solar Cycles 23 & 24. The variation of the tilt angles with the maximum magnetic-field strength of the ARs indicates a nonlinear tilt quenching in the Babcock–Leighton process.

Study of Sunspot Penumbra to Umbra Area Ratio Using Kodaikanal White-light Digitised Data

Solar Physics 294:72 (2019)

Sunspots, which are the dark fetures, seen on the solar visible surface, have two part structure. The central darker region called umbra and relativly lighter region around it is called penumbra. In this work we have extraced these fetures based on image processing technique from the digitized images at Kodiakanal Solar Observatory (KoSO) for the period 1923-2011. And then we studied the variation of their area ratio with time. We have also studied the its various aspects in the context of solar cycles.


Delving into the Historical Ca ii K Archive from the Kodaikanal Observatory: The Potential of the Most Recent Digitized Series

Solar Physics 294:145 (2019)

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Long-term variation of sunspot penumbra to umbra area ratio

Proceedings of the International Astronomical Union Volume 13 Symposium S340 (2018)

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  • Computer Programming (6+ Years)
  • Data Analysis (5+ Years)
  • Image Processing (4+ Years)
  • Photoshop & Lightroom (5+ Years)