Probable detection of an eruptive filament from a superflare on a solar-type star

Solar flares are often accompanied by filament/prominence eruptions (~104 K and ~1010−11 cm−3), sometimes leading to coronal mass ejections that directly affect the Earth’s environment1,2. ‘Superflares’ are found on some active solar-type (G-type main-sequence) stars3–5, but the filament eruption–coronal mass ejection association has not been established. Here we show that our optical spectroscopic observation of the young solar-type star EK Draconis reveals evidence for a stellar filament eruption associated with a superflare. This superflare emitted a radiated energy of 2.0 × 1033 erg, and a blueshifted hydrogen absorption component with a high velocity of −510 km s−1 was observed shortly afterwards. The temporal changes in the spectra strongly resemble those of solar filament eruptions. Comparing this eruption with solar filament eruptions in terms of the length scale and velocity strongly suggests that a stellar coronal mass ejection occurred. The erupted filament mass of 1.1 × 1018 g is ten times larger than those of the largest solar coronal mass ejections. The massive filament eruption and an associated coronal mass ejection provide the opportunity to evaluate how they affect the environment of young exoplanets/the young Earth6 and stellar mass/angular momentum evolution7.

Low cost equipment for astronomical spectroscopy

The purpose of this paper is to show how we can obtain spectra for different astronomical objects using low coat equipment. Where a high-efficiency diffraction grating named “The Star Analyzer” was used by the International Astronomical Center (IAC) in Abu Dhabi, UAE to get the spectrum of different astronomical objects. Balmer series was readily visible when observing an “A” type star. TiO absorptions lines were distinguished by observing an “M” type star. Methane absorption lines were visible by observing Uranus and Neptune. Whereas HI and HeI emission lines were detected by observing a blue hypergiant. In addition, C2 Swan band absorption lines were identified by observing a red giant carbon star. This type of observation is very interesting for public outreach as well as university students, because it shows astrophysical principles for public and students practically and by using low cost equipment.

TESS observations of KIC 7739728 - a new FK Com type star candidate

Ранее по данным наблюдений с космическим телескопом “Kepler” нами было показано, что по своим параметрам KIC 7739728 близка к звездам типа FK Com и может рассматриваться, как потенциальный кандидат для включения в число объектов этого типа. В настоящей работе мы провели анализ всех имеющихся для KIC 7739728 данных в архиве миссии TESS (14 и 26 сектора наблюдений). Показано, что кривая блеска этой звезды ярко проявляет свойства регулярной вращательной модуляции и что в период времени между 14 и 26 секторами произошло явление переключения положений долгот активных областей на поверхности звезды (флип-флоп). Рассматриваются аргументы в пользу возможной принадлежности KIC 7739728 к объектам типа FK Com. Using the observations with the Kepler space telescope we found that parameters of KIC 7739728 are close to that ones of the FK Com type stars and that the object can be considered as a potential candidate for inclusion in the number of objects of this type. In this paper we analysed all available data for KIC 7739728 in the TESS mission archive (14 and 26 sectors). It is shown that the light curve of this star clearly exhibits the properties of regular rotational modulation and that in the time interval between 14 and 26 sectors the phenomenon of switching the positions of the longitudes of the active regions on the surface of the star (flip-flop) occurred. The arguments in favour of the possible relation of KIC 7739728 to objects of the FK Com type are considered.

Certain Class of Analytic Functions with respect to Symmetric Points Defined by Q-Calculus

In this study, we familiarise a novel class of Janowski-type star-like functions of complex order with regard to j , k -symmetric points based on quantum calculus by subordinating with pedal-shaped regions. We found integral representation theorem and conditions for starlikeness. Furthermore, with regard to j , k -symmetric points, we successfully obtained the coefficient bounds for functions in the newly specified class. We also quantified few applications as special cases which are new (or known).