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Dr. Bidya Binay Karak
Assistant Professor
Department of Physics, IIT (BHU)
0542 7165489
Area of Interest: 
Astrophysics, Stellar and Solar Physics; Magnetohydrodynamics (MHD) and its applications, dynamo theory, astrophysical fluids, turbulence, convection, magnetic field, sunspot, solar and stellar cycles, nonlinear and chaotic behaviors of astrophysical objects.

I am presently an assistant professor in the Department of Physics, IIT (BHU), Varanasi. I am also a Ramanujan Fellow through the Department of Science and Technology, Gov. of India. I have recently received a prestigious fellowship: Humboldt fellowship from Humboldt Foundation Germany and an award: INSA Young Scientist Medal (2019) from Indian National Science Academy. 
I primarily work on solar and stellar physics, specifically trying to understand the origin of the solar and stellar magnetic field and its dynamics using magnetohydrodynamics. Previously, I 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). 

Contact details:
Department of Physics, Indian Institute of Technology (Banaras Hindu University),
Varanasi 221005, Uttar Pradesh, India


Currently, I have funding for a Postdoc (through my Ramanujan Fellowship grant).  Only highly motivated candidates having exceptional academic records are encouraged to contact me.

My publications can be found on

the Google Scholar page
SAO/NASA Astrophysics Data System (ADS)

Manuscript Submitted/Accepted:

31. Z. Yang, C. Bethge, H. Tian, S. Tomczyk, R. Morton, G. Zanna, SW. McIntosh, B. B. Karak, S. Gibson, T. Samanta, J. He, Y. Chen, L. Wang: Global maps of the magnetic field in the solar corona​ (2020), Science  (accepted).

Manuscript Published:
International Journals

30. Jha, B. Karak, B. B., Mandal, S., & Banerjee, D.:
     Magnetic field dependence of bipolar magnetic region tilts on the Sun: Indication of tilt quenching​ (2020), ApJL  889, p7; arxiv.org/abs/1912.13223.

29. Karak, B. B., Tomar, A.,& Vashishth, V.:
      Stellar Dynamos with Solar and Anti-solar Differential Rotations: Implications to Magnetic Cycles of Slowly Rotating Stars, (2019), MNRAS, 491, 3155, arXiv:1910.11893​

28. Garg, S., Karak, B. B., Ricky Egeland, Soon, W.  & Baliunas, S:
      Waldmeier Effect in Stellar Cycles, (2019), The Astrophysical Journal 886, 132; arXiv: 1909.12148

27. Hazra, G., Jiang, J. Karak, B. B., & Kitchatinov, L. L.:
      Exploring cycle period and parity of stellar magnetic activity with dynamo modeling, (2019), The Astrophysical Journal 884, 35, arxiv.org/abs/1909.01286

26. Karak, B. B., Mandal, S., & Banerjee, D.:
      Double-peaks of the solar cycle: An explanation from a dynamo model, arXiv:1808.03922 (2018), The Astrophysical Journal, 866, 17.

25. Srivastava, A. K.; McIntosh, S. W.; Arge, N.; Banerjee, D.; Cliver, E.; Dikpati, M.; Dwivedi, B. N.; Guhathakurta, M.; Karak, B. B. et al. 
      The Extended Solar Cycle: Muddying the Waters of Solar/Stellar Dynamo Modeling Or Providing Crucial Observational Constraints? arXiv:1807.07601 (2018).

24. Karak, B. B. & Miesch, M.:
            Recovery from Maunder-like Grand Minima in a Babcock--Leighton Solar Dynamo Model, Astrophysical Journal, 860, L26 (2018).

23. Karak, B. B., Miesch, M. & Bekki, Y.: Effects of Prandtl number on the stellar convection and differential rotation, Physics of Fluids, 30, 046602, arXiv:1801.00560 (2018).

22. Mandal, S., Karak, B. B. & Banerjee, D.: Latitude distribution of sunspots: analysis using sunspot data and a dynamo model, The Astrophysical Journal, 851, 70, arXiv:1711.00222 (2017).

21. Karak, B. B. & Miesch, M.: Solar cycle variability induced by tilt angle scatter in a Babcock–Leighton solar dynamo model, The Astrophysical Journal, 847, 69, arXiv:1706.08933 (2017).

20. Karak, B. B. & Cameron, R.: Babcock-Leighton solar dynamo: the role of downward pumping and the equatorward propagation of activity, The Astrophysical Journal, 832, 94, arXiv:1605.06224 (2016).

19. Karak, B. B. & Brandenburg, A.: Is the small-scale magnetic field correlated with the dynamo cycle? The Astrophysical Journal, 816, 28, arXiv:1505.06632 (2016).

18. Käpylä, M. J., Käpylä, P., Olspert, N., Brandenburg, A. Warnecke, J., Karak, B. B. & Pelt, J.: Multiple dynamo modes as a mechanism for long-term solar activity variations, Astronomy and Astrophysics, 589, 56, arXiv:1507.05417 (2016).

17. Karak, B. B., Kitchatinov, L. L. & Brandenburg, A.: Hysteresis between distinct modes of turbulent dynamos, The Astrophysical Journal, 803, 95, arXiv:1411.0485 (2015).

16. Hazra, G., Karak, B. B., Banerjee, D. & Choudhuri, A. R.: Correlation between Decay Rate and Amplitude of Solar Cycles as Revealed from Observations and Dynamo Theory, Solar Physics, 290, 1851, arXiv:1410.8641 (2015).

15. Karak, B. B., Käpylä, P., Käpylä, M. J. Brandenburg, A., Olspert, N. & Pelt, J.: Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles, Astronomy and Astrophysics, 576, 26, arXiv:1407.0984 (2015).

14. Karak, B. B., Rheinhardt, M., Brandenburg, A., Käpylä, P. J. & Käpylä, M. J.: Quenching and anisotropy of hydromagnetic turbulent transport. The Astrophysical Journal, 795, 16, arXiv:1406.4521 (2014).

13. Priyal, M., Banerjee, D., Karak, B. B., Munoz-Jaramillo, A., Ravindra, B., Choudhuri, A. R. & Singh, J.: Polar Network Index as a magnetic proxy for the solar cycle studies. The Astrophysical Journal Letters, 793, L4, arXiv:1407.4944 (2014).

12. Karak, B. B., Kitchatinov, L. L. & Choudhuri, A. R.: A Dynamo Model of Magnetic Activity in Solar-like Stars with Different Rotational Velocities. The Astrophysical Journal, 791, 59, arXiv:1402.1874 (2014).

11. Hazra, G., Karak, B. B. & Choudhuri, A. R.: Is a Deep One-cell Meridional Circulation Essential for the Flux Transport Solar Dynamo? The Astrophysical Journal, 782, 93, arXiv:1309.2838 (2014).

10. Karak, B. B. & Choudhuri, A. R.: Studies of grand minima in sunspot cycles by using a flux transport solar dynamo model. Research in Astronomy and Astrophysics, 13, 1339, arXiv:1306.5438 (2013).

9. Karak, B. B. & Petrovay, K.: On the compatibility of a flux transport dynamo with a fast tachocline scenario. Solar Physics, 282, 321, arXiv:1209.0319 (2013).

8. Karak, B. B. & Nandy, D.: Turbulent Pumping of Magnetic Flux Reduces Solar Cycle Memory and thus Impacts Predictability of the Sun’s Activity. The Astrophysical Journal Letters, 761,
L13, arXiv:1206.2106.
7. Choudhuri A. R. & Karak, B. B.: The origin of grand minima in the sunspot cycle. Physical Review Letters, 109, 171103, arXiv:1208.3947 (2012).

6. Karak, B. B. & Choudhuri, A. R.: Quenching of Meridional Circulation in Flux Transport Dynamo Models. Solar Physics, 278, 137, arXiv:1111.1540 (2012).

5. Karak, B. B. & Choudhuri, A. R.: The Waldmeier effect and the flux transport solar dynamo. Monthly Notices of the Royal Astronomical Society, 410, 1503, arXiv:1008.0824 (2010).

4. Karak, B. B.: Importance of Meridional Circulation in Flux Transport Dynamo: Possibility of Maunder-like Grand Minimum. The Astrophysical Journal, 724, 1021, arXiv:1009.2479 (2010). 

3. Karak, B. B., Dutta, J. & Mukhopadhyay, B.: Search for Chaos in Neutron Star Systems: Is Cyg X-3 a Black Hole?. The Astrophysical Journal, 708, 862, arXiv:0911.1701 (2010).

2. Choudhuri, A. R. & Karak, B. B.: A possible explanation of the Maunder minimum from a flux transport dynamo model. Research in Astronomy and Astrophysics (Letters), 9, 953, arXiv:0907.3106 (2009).

1. Karak, B. B., Jiang, J., Miesch, M., Charbonneau, P. & Choudhuri, A. R.: Flux transport dynamos: from kinematics to dynamics. Space Science Review, 186, 561, [download]. [This is basically a proceedings review produced by combining the presentations of above authors at the ISSI Bern workshop.]

1. Verma, M., Karak, B. B. & Kumar, R.: Dynamo in protostars. Pramana, 81, 1037, arXiv:1304.6808 (2013).

Some of the selected awards I have received are listed here:
INSA Young Scientist Medal (2019) from Indian National Science Academy.
2018 – 2021: Humboldt Research Fellowship from the Alexander von Humboldt Foundation, Germany.
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.
2013: Justice Oak best thesis award from Astronomical Society of India (ASI).
2013 – 2015: NORDITA Fellowship from NORDITA, Nordic Institute for Theoretical Physics, Sweden.
2013 – 2016: Postdoctoral fellowship in Kiepenheuer Institute for Solar Physics, Germany (declined).
2008 – 2013: Research Fellowship awarded (twice) by the Council of Scientific and Industrial Research, Govt. of India.
2003: National Merit Scholarship based on West Bengal Higher Secondary exams.

Sponsored Project (current):
Nov 2019 – Nov 2022: “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.  

Aug 2013:
PhD, Department of Physics, Indian Institute of Science (IISc), Bangalore, India. 
Thesis title: Theoretical study of the solar magnetic cycle and its irregularities. Advisor: Prof. Arnab Rai Choudhuri

Jul 2009: M.S. (Physics), IISc, Bangalore, India.

Aug 2006: B.Sc. (with Physics Honours and Mathematics and Chemistry as subsidiary subject), Bankura Christian College, Burdwan University, Bankura, India.

May 2018 – Present: Assistant Professor, Indian Institute of Technology, Varanasi (IIT-BHU), India.
Jan – Apr 2018: Chandrasekhar Postdoctoral fellow, Indian Institute of Astrophysics, Bangalore, India.
Jan 2016 – Jan 2018: Jack Eddy Postdoctoral fellow, High Altitude Observatory, National Center for Atmospheric Research (NCAR), Boulder, CO, USA.
Sep 2015 – Dec 2015​: Guest Scientist, Max Planck Institute for Solar System Research (MPS), Göttingen, Germany.
Sep 2013 – Aug 2015​: NORDITA Postdoctoral fellow, NORDITA Nordic Institute for Theoretical Physics, Stockholm,

Please find my full CV here.

Areas of research interest:
Astrophysics, specifically, magnetohydrodynamics (MHD) and its applications to the Sun and other stars; Dynamo theory and origin of magnetic fields in stars, planets and galaxies; Astrophysical fluids, turbulence, and convection; Large-scale flows such as differential rotation and meridional circulation in the solar convection zone, sunspot and solar cycle; Effect of solar cycle on the Earth’s global climate; and Nonlinear and chaotic behaviors of astrophysical objects.

Major research experience:
In my PhD thesis, I explored the origin and the evolution of Sun’s large-scale magnetic field, the solar cycle and particularly their irregular features such as the Waldmeier effect and grand minima using two-dimensional Babcock-Leighton/flux transport dynamo models. Later I worked on simulations of MHD turbulence and small- and large-scale dynamos in Cartesian geometry as well as the global spherical geometry of solar convection zone with the Pencil Code. Currently, I am working on a state-of-the-art 3D Surface Transport and Babcock-LEighton (STABLE) dynamo model for the solar cycle and planning to extend it to other stars, and the solar convection.

I like to work with students and postdocs. If you are interested in discussing with me, you are welcome to meet/contact me. Currently, I have funding for a Postdoc. Highly motivated and bright candidates are encouraged to contact me.  Students having his/her own fellowship are also welcomed.

I have collaborators at Indian Indian Institute of Astrophysics, India, National Centre for Atmospheric Research, USA, NORDITA, Sweden, and Max Plank Institute for Solar System Research, Germany. Thus collaborative projects may also be started.

2018: Odd Semester:

PHY-102: Introduction to Engineering Electromagnetics (BTech)
PHY-302:  Relativistic Electrodynamics (BTech)
EP-511:  Space Weather (MTech)

2019: Even Semester:

PHY-504: Advanced Mathematical and Computational Physics (MSc)
PHY-412:  Physics of Sun and its Atmosphere (BTech)
PHY-211:  Solar and Space Plasma Physics (BTech)

2019: Odd Semester:

PHY-102: Introduction to Engineering Electromagnetics (BTech)
PHY-302: Relativistic Electrodynamics (BTech)
PHY-404: Classical Electrodynamics (MSc)

PhD students:
Pawan Kumar
(2019 Jan- present), IIT (BHU) JRF through GATE and NET JRF: Working on the surface transport model for the solar surface magnetic field.
Vindya Vashishth (2019 Aug- present), IIT (BHU) JRF through DST-INSPIRE: Yet to start PhD project.

Project students:
Exploratory Project:
One BTech student in Engineering Physics
UG Project: Gandhi Aarsh Amulkumar (5-year in Engineering Physics)
MTech Project: Kalva Aravind (5-year in Engineering Physics)
External Student: Arun Sharma (BTech from IIT-BHU)

Previous students:
Feb 2018 – Dec 2019: Bibhuti Kumar Jha, PhD student from Indian Institute of Astrophysics; worked on magnetic field dependence of BMR tilt. The paper got published in ApJL.
Mar 2019 – May 2019: Aparna Tomar, MSc, Uni. Delhi, worked with me on Stellar dynamos with solar and anti-solar differential rotations; the paper has been published in MNRAS.
Dec 2018 – Jul 2019: Suyog Garg, BTech student from IIIT-DM, worked with me on Stellar magnetic cycles of solar-type stars. the paper has been published in ApJ.
Sep 2016 – Dec 2017: Partially mentored a PhD student, Sudip Mandal at Indian Institute of Astrophysics, Bangalore on a project: Latitudinal Distribution of Sunspots: Lesson from Dynamo Theory.
Sep 2017 – Oct 2018: Partially mentored a MS student, Yuto Bekki, The University of Tokyo, on a project: Understanding the solar convection in global MHD simulations.
2016 – August 2016: Kirsten McMichael, a student under Research Experience for Undergraduates (REU) Program in Solar and Space Physics at the University of Colorado, USA; project: Calibrating Your Cosmic Compass: What Determines the Magnetic Field Strength at the Sun’s North and South Poles?
Jun – Jul 2016: Anna Parker, REU Program in Solar and Space Physics at the University of Colorado, USA; project: Seeing Spots: Using supercomputer models to ask why all solar cycles are not created equal.
Jul 2015: Alexandra Berg and Alfred Isaac, students from Rays for excellence, Research Academy for Young Scientists, Sweden; projects: Effect of diffusivity quenching in kinematic mean-field dynamo model and Determination of the equatorward propagation speed of sunspots.
Jun 2014 Partially guided Jakob Broman, Ottilia Andersson and Toomas Liiv, students from Rays for excellence, Research Academy for Young Scientists, Sweden; projects: Chaotic oscillator, and Energy budgets of charged particles moving in a time-varying magnetic field.
Mar – Aug 2013 Partially mentored a beginner PhD student, Gopal Hazra at IISc, Bangalore; projects: (i) Multi-cell meridional circulation and its effect on kinematic mean-field dynamo models, and (ii) Correlation between decay rate and amplitude of solar cycles as revealed from observations and dynamo theory.


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