The observations of solar flare onsets show rapid increase of hard and soft X-rays, ultra-violet emission with large Doppler blue shifts associated with plasma upflows, and Hα hydrogen emission with red shifts up to 1-4 Å. Modern radiative hydrodynamic models account well for blue-shifted emission, but struggle to reproduce closely the red-shifted Hα lines. Here we present a joint hydrodynamic ...

We present B, R, and Hα imaging data of 19 large disk galaxies whose properties are intermediate between classical low surface brightness galaxies and ordinary high surface brightness galaxies. We use data taken from the Lowell 1.8m Perkins telescope to determine the galaxies’ overall morphology, color, and star formation properties. Morphologically, the galaxies range from Sb through Irr and i...

We discuss the selection and observations of a large sample of nearby galaxies, which we are using to quantify the star formation activity in the local Universe. The sample consists of 334 galaxies across all Hubble types from S0/a to Im and with recession velocities of between 0 and 3000 km s−1. The basic data for each galaxy are narrow band Hα+[N] and R-band imaging, from which we derive st...

The results of Hα and [NII]λ6583 observations of the spiral galaxy NGC 1084 at the SAO 6m telescope with a Fabry-Perot interferometer are presented. The complex structure of the emission line profile has revealed the presence of giant star formation regions (“spur”) in the NE part of the galaxy. In this region the Hα line shows two distinct components, with line-of-sight velocity differences of...

OB–stars have the highest luminosities and strongest stellar winds of all stars, which enables them to interact strongly with their surrounding ISM, thus creating bow shocks. These offer us an ideal opportunity to learn more about the ISM. They were first detected and analysed around runaway OB–stars using the IRAS allsky survey by van Buren et al. (1995). Using the geometry of such bow shocks ...

The almost Mathieu operator is the discrete Schrodinger Hα,β,θ on \(\ell ^2(\mathbb {Z})\) defined via \((H_{\alpha ,\beta ,\theta }f)(k) = f(k + 1) - \beta \cos {}(2\pi \alpha k \theta ) f(k)\). We derive explicit estimates for eigenvalues at edge of spectrum finite-dimensional \({H^{(n)}_{\alpha }}\). furthermore show that (properly rescaled) m-th Hermite function ϕm an approximate eigenvecto...

objective(s): this study addresses feature selection for breast cancer diagnosis. the present process uses a wrapper approach using ga-based on feature selection and ps-classifier. the results of experiment show that the proposed model is comparable to the other models on wisconsin breast cancer datasets. materials and methods: to evaluate effectiveness of proposed feature selection method, we ...

Abstract We study a sample of 119 Herbig Ae/Be stars in the Galactic anti-center direction using spectroscopic data from Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) survey program. Emission lines hydrogen belonging to Balmer and Paschen series, metallic species such as Fe ii, O i, Ca ii triplet are identified. A moderate correlation is observed between emission strengths ...

Aims. The main aim of the present analysis is to decipher (i) small-scale bright features in solar images quiet Sun and active regions obtained with Atacama Large Millimeter/submillimeter Array (ALMA) (ii) ALMA correspondence various known chromospheric structures visible Hα Sun.

Using 1D NLTE radiative hydrodynamics we model the influence of the particle beams on the Hα line profile treating the beam propagation and the atmosphere evolution self-consistently. We focus on the influence of the non-thermal collisional rates and the return current. Based on our results, we propose a diagnostic method for determination of the particle beam presence in the formation regions ...