Speaker
Dr
Subhajeet Karmakar
(Aryabhatta Research Institute of Observational Sciences (ARIES))
Description
Solar-type stars with a similar internal structure to that of the Sun (spectral type from late-F to early-M) are supposed to operate a similar type of dynamo mechanism. However, the observations of these stars have introduced a range of stellar rotation periods, gravities, masses, and ages, which put into the debate on the existing magnetic dynamo theory. In order to provide useful constraints for the dynamo theory, we are currently working on a project to investigate the magnetic activities of the stars with the same internal structure. We have chosen the F-type star KIC6791060, the K-type star LO Pegasi, and M-type planet-hosting stars EPIC211901114 and K2-33. We intend to compare the results with those of the Sun. Using several ground-based (mostly from BINA telescopes) and space-based observatories, we intend to study the photospheric, upper chromospheric and coronal activity indicators. Using ~24 years long multi-band photometric data, we derive the rotational period of LO Peg to be 0.4231 ± 0.0001 d. Using the seasonal variations on the rotational period, the surface differential rotation (SDR) pattern is investigated and shows a solar-like pattern of SDR with a period of ∼2.7 yr. A total of 20 optical flares are detected with a flare frequency of ∼1 flare per two days and a flare energy of ∼10^{31–34} erg. The surface coverage of cool spots is found to be in the range of ∼9–26%. A flip-flop cycle of ~1 yr appears to be present. Using 4 years long multi-band observations of KIC6791060 and three months observations of EPIC211901114 and K2-33 along with the observations with ground-based observatories, we have recreated the surface inhomogeneity map. We also analysed for habitability on those orbiting planets.
Primary author
Dr
Subhajeet Karmakar
(Aryabhatta Research Institute of Observational Sciences (ARIES))
Co-authors
Dr
Ashish Raj
(Indian Institute of Astrophysics)
Prof.
Igor Savanov
(Institute of Astronomy RAS 48 Pyatnitskaya str.119017 Moscow Russia)
Dr
Jeewan Pandey
(Aryabhatta Research Institute of Observational Sciences)
