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SOLAR  AND  STELLAR  MAGNETISM  RESEARCH

@Indian  Institute  of  Technology  (BHU),  Varanasi

 

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About Us

Our group the Solar and Stellar Magnetism here @ IIT (BHU) is trying to understand the origin and dynamics of solar and stellar magnetic fields, cycles, plasma flows inside the convection zones of sun and other stars.

 

We apply the magnetohydrodynamics (MHD) model in the solar plasma to develop various types of dynamo models to understand the generation of the solar magnetic cycle and its irregularities. For the last several years, we have applied Babcock-Leighton type flux transport dynamo models to explain various long-standing problems of the solar magnetic cycles, including the Waldmier effect, Maunder and grand minima, and double peaks in the solar cycle.  Our group is  also exploring the physics of solar cycle prediction and have recently predicted the amplitude of the upcoming solar cycle. We are also involved in developing dynamo models of the magnetic cycles of the sun-like stars.

 

Our research team also analyses various data sets of solar magnetic field and other proxies from different ground- and space-based observatories to unveil the magnetic mysteries of the sun and sun-like stars. We also work on understanding the chaotic and nonlinear aspects of astrophysical time series. 

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Dr. Bidya Binay Karak

Dr. Karak is presently an assistant professor in the Department of Physics, IIT (BHU), Varanasi.

 

He is also a Ramanujan Fellow through the Department of Science and Technology, Government of India. He has recently received a prestigious fellowship: Humboldt fellowship from Humboldt Foundation Germany (2018) and an award: INSA Young Scientist Medal (2019) from Indian National Science Academy. 
 

Dr. Karak primarily works on solar and stellar physics, specifically trying to understand the origin of the solar and stellar magnetic fields and their dynamics using magnetohydrodynamics.

 

Previously, he was a Chandrasekhar postdoctoral fellow at the Indian Institute of Astrophysics (Jan 2018 - Apr 2018), Jack Eddy fellow (supported by NASA Living With a Star program) at the National Center for Atmospheric Research, Colorado, USA (Jan 2016 - Jan 2018), Guest Scientist at the Max Planck Institute for Solar System Research, Germany (Sept 2015 - Dec 2015), and Nordita fellow at NORDITA, Stockholm (Sept 2013 - Aug 2015).

Meet our Group

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         Pawan Kumar                             

Vindya Vashishth

Akash Biswas

Anu B Sreedevi

Research Scholar,

Department of Physics, IIT (BHU)

Ph.D. Thesis Title:  Understanding the generation, evolution and importance of the polar magnetic field in the Sun.

Please find my CV here.

Research Scholar,

Department of Physics, IIT (BHU)

Ph.D. Thesis Title:  Understanding the variabilities of magnetic cycles of Sun-like stars through dynamo modelling.

Please find my  CV here.

Research Scholar,

Department of Physics, IIT (BHU)

Ph.D. Thesis Title:  Surface transport model for the solar surface magnetic field; physics of solar cycle prediction.

Please find my CV here.

Research Scholar,

Department of Physics, IIT (BHU)

Ph.D. Thesis Title:  Long-term study  of different proxies of solar activity and their implication in dynamo modeling.

Please find my CV here.

 
 

Updated: Jun 6


Prediction based on the polar field rise rate suggests that Solar Cycle 25 will be slightly stronger than Cycle 24


Our latest work was published in HMI Science Nuggets on April 28th 2022.

A new model, which explores the polar field build-up rate and the amplitude of the following cycle, predicts a slightly stronger Cycle 25 than previously thought. It shows physical link of the polar field buildup with the Waldmeier Effect broadens the scope of early solar cycle prediction: Cycle 25 is likely to be slightly stronger than Cycle 24.

Fig: Comparison of our prediction with observations. Temporal variation of the observed SSN is shown by the blue curve. Squares and vertical lines represent the predicted amplitudes and their errors based on the rise rate (WE2). The time of the peak of predicted Cycle 25 is shown by the vertical dotted line with the error by a horizontal arrow. The prediction for Cycle 25 using the rise rate of the previous cycle’s polar field is shown by a (dark red) filled circle.


In other news:

Invited Talk of Dr. Bidya Binay Karak at ISSI Dynamo Workshop on 16th June 2022. [Upcoming]


Invited Talk of Akash Biswas at ISSI Dynamo Workshop on 16th June 2022. [Upcoming]


Invited Talk by Dr. Bidya Binay Karak at IAUGA2022 on 2nd August 2022 . [Upcoming]



Contributed Talk by Vindya Vashishth at IAUGA2022 on 2nd August 2022 . [Upcoming]


E-Talk by Anu B Sreedevi at IAUGA2022 . [Upcoming]

News Highlights

  • Prediction of the solar cycle is challenging, however, essential as the solar activity drives space weather, which sometimes has hazardous effects on our space-based society. Several predictions for the amplitude of the ongoing Solar Cycle 25 have been made but it was still not clear how strong the cycle is going to be. We have recently shown that the ongoing Solar Cycle 25 is going to be a little stronger than the previous cycle. Here is the research paper: https://ui.adsabs.harvard.edu/abs/2022arXiv220311494K/abstract.    We have also shown that the amplitude of the solar cycle can be predicted after about three years of the previous cycle polar field reversal (or a few years before the solar cycle minimum which is the usual time of the solar cycle prediction. https://ui.adsabs.harvard.edu/abs/2021ApJ...909...87K/abstract 

 

  • Reconstructed the solar surface magnetic field for the first time during 1915--1965 using Kodaikanal Solar Observatory data. This work is an outcome of the Indo-Russian bilateral collaboration. The research paper has been published in ApJL. The work has been highlighted on different platforms: DST, The Hindu, Anandabajar

 

 

 

 

  • Became the Active Member (Junior Member) of International Astronomical Union (IAU).

 

 

 

  • Received prestigious:  ​​ ​​

       (i) Humboldt Research Fellowship from the Alexander von Humboldt Foundation, Germany (2021-2022).
        (ii) Ramanujan Fellowship from SERB/DST, India (2018-2023)

Recent Invited Talks

  • "Some Recent Developments in the Babcock–Leighton Solar Dynamo Theory", in dynamo & solar cycle RSWG meeting, Max Plank Institute of Solar System Research, Germany, Feb 2022

  • "Nonlinearities for the saturation of magnetic field in the Sun, International conference: IIA-50 “Advances in Observation and Modelling of Solar Magnetism and Variability", March 2021

  • "Recent Developments in the Babcock–Leighton Solar Dynamo Theory, The 39th Annual Meeting of the Astronomical Society of India (ASI), 28-23 Feb 2021, Feb 2021.

  • Understanding and Modeling the Magnetic Cycles of Sun and Sun-like Stars, Colloquium at NCRA, Pune, India, Jan 2020.

  • Understanding the stellar magnetic cycles using dynamo modellings, Conference on Plasma Simulation (CPS-2020) at Institute for Plasma Research Gandhinagar, Jan 2020.

  • Quenching and scatter in BMR tilts, Team Meeting at International Institute for Space Science, Bern, Switzerland, Nov, 2019.

  • Solar Magnetic Fields and Cycles: Understanding the Solar Dynamo and Differential Rotation, IIT-Delhi, New Delhi, India, May 2019.

  • Why do the magnetic fields in sun and other stars vary irregularly?, Presentation for INSA Medal for Young Scientists, Apr 2019.

Recent Publication

  • P. Kumar, A. Biswas, A. & B. B. Karak: Physical link of the polar field buildup with the Waldmeier effect broadens the scope of early solar cycle prediction: Cycle 25 is likely to be slightly stronger than Cycle 2 Monthly Notices of the Royal Astronomical Society: Letters 513 (1), L112-L116.

  • A. Biswas, A., B. B. Karak R., & Cameron: Toroidal flux loss due to flux emergence explains why all solar cycles decline in the same way, submitted (2022). (Submitted/Accepted)

  •  A. V. Mordvinov, B. B. Karak, D. Banerjee, E. M. Golubeva, A. L. Khlystova, A. V. Zhukova, & P. Kumar:  Evolution of the Sun’s magnetic fields and their reversals in Cycles 21–24: A closer look, MNRAS, 510, 1331; arxiv.org/abs/2111.15585​ (2022) (Impact Factor: 5.36)

  • 38. R. Das, Ghosh, A. & B. B. Karak:
          Is the Hemispheric Asymmetry of Monthly Sunspot Area an Irregular Process with Long-Term Memory, MNRAS, 551, 472; arxiv.org/abs/2111.06332 (2022)​ (Impact Factor: 5.36)

  • 37. P. Kumar, B. B. Karak & V. Vashishth:
          Super-criticality of dynamo limits the memory of polar field to one cycle, The Astrophysical Journal, 913, 65; arxiv:2103.11754 (2021) (Impact Factor: 5.75).

  • 36. V. Vashishth, B. B. Karak, & L. Kitchatinov:
          Subcritical dynamo and hysteresis in a Babcock-Leighton type kinematic dynamo model, Research in Astronomy and Astrophysics 21, 266 (2021) (Impact Factor: 1.25).

  • 35. P. Kumar, Nagy, M., L. Alexandre, B. B. Karak & K. Petrovay:
          The polar precursor method for solar cycle prediction: comparison of predictors and their temporal range, The Astrophysical Journal 909, 87; arXiv:2101.05013 (2021) (Impact Factor: 5.75).

Awards and Fellowships

  • 2022: Dr.Bidya Binay Karak, Vindya Vashishth and Anu B Sreedevi received travel grant of 5000€ for IAUGA-2022

  • 2021: Mr. Akash Biswas has been awarded Junior Research Fellowship by CSIR-UGC, Govt. of India in the June-2021 cycle.

  • 2021: Humboldt Research Fellowship from the Alexander von Humboldt Foundation, Germany.

  • 2019: INSA Young Scientist Medal (2019) from Indian National Science Academy.

  • 2018: Chandrasekhar Postdoctoral Fellowship (equivalent to a reader position) from Indian Institute of Astrophysics, Bangalore.

  • 2015: Asia-Pacific Solar Physics Meeting (APSPM) Best Paper Award, South Korea.

  • 2015: Thomas Metcalf Lecturer and SPD Travel Award - American Astronomical Society (AAS) Solar Physics Division (SPD), USA.

  • 2015 – 2017: Jack Eddy Postdoctoral Fellowship award from UCAR and NASA Living With a Star program, USA.​

  • 2015 – 2017: Research Fellowship from Max Planck Institute for Solar System Research, Germany (declined).

  • 2014 – 2015: Kumari L A Meera Memorial Medal for the best thesis in Theoretical Physics, IISc, Bangalore.

Projects

  • Feb 2020 – Feb 2023: “On understanding the solar activity and preparing for space weather prediction using a state-of-art dynamo model", under RESPOND program of ISRO, grant amount: 30.99 lakhs.

  • Nov 2019 – Nov 2021: “Multiple reversals of the Sun’s polar-fields and their physical causes", under DST-RFBR program of DST, grant amount: 10.45 lacks.

  • Nov 2018 – Nov 2023: “Exploring the origin and dynamics of magnetic cycles of low main sequence stars" under Ramanujan Fellowship from SERB, DST, grant amount: 38 lakhs.

  • Nov 2019 - Nov 2021: "What Determines The Dynamo Effectivity Of Solar Active Regions?" led by Prof. K. Petrovay, sponsor: by International Space Science Institute, Bern, Switzerland, grant amount: travel expense.  

 

"The purpose of life is to study the Sun, the moon and the heavenly bodies"
                                                           -Anaxagoras