Soft X-ray (SXR) waves, EIT waves, and Hα Moreton waves are all associated with coronal mass ejections (CMEs). The knowledge of the characteristics about these waves is crucial for the understanding of CMEs, and hence for the space weather researches. MHD numerical simulation is performed, with the consideration of the quiet Sun atmosphere, to investigate the CME/flare processes. On the basis o...

In this paper we study certain properties of Rényi entropy functions Hα(P) on the space of discrete probability distributions with infinitely many probability masses. We prove some properties that parallel those known in the finite case. Some properties on the other hand are quite different in the infinite case, for example the (dis)continuity in P and the problem of divergence and behaviour of...

We present the results of narrow-band Hα+[N II] imaging of the early-type spiral NGC 3593 in combination with a study of the flux radial profiles of the [N II] (λλ 654.80, 658.34 nm), Hα, and [S II] (λλ 671.65, 673.08 nm) emission lines along its major axis. The galaxy is known to contain two counterrotating stellar discs of different size and luminosity. We find that the Hα emission mainly der...

In this paper we present deep broadand narrowband images (JohnsonB, Gunn-red, Hα, Hα+[NII], [NII], [OIII]) and high resolution spectroscopy (Fabry-Pérot interferometer (Hα, Hβ, [NII], [OIII]) and Coudé measurements (Hα, [NII])) for the planetary nebula (PN) M1-79. Systemic and expansion velocities are investigated alongwith themorphological characteristics of this PN.M1-79 exhibits an elliptica...

We investigate the [O II] emission-line as a star formation rate (SFR) indicator using integrated spectra of 97 galaxies from the Nearby Field Galaxies Survey (NFGS). The sample includes all Hubble types and contains SFRs ranging from 0.01 to 100 M⊙ yr . We compare the Kennicutt [O II] and Hα SFR calibrations and show that there are two significant effects which produce disagreement between SFR...

High resolution spectra of 123 red giant stars in the globular cluster M13 and 64 red giant stars in M92 were obtained with Hectochelle at the MMT telescope. Emission and line asymmetries in Hα, and Ca II K are identified, characterizing motions in the extended atmospheres and seeking differences attributable to metallicity in these clusters and M15. On the red giant branch, emission in Hα gene...

We present the results of medium resolution (∆v ≈ 60 km s) spectropolarimetric observations across Hα of a sample of B[e] and Herbig Be objects. A change in linear polarization across Hα is detected in a large fraction of the objects, with characteristics ranging from simple depolarization in a couple of Herbig Be stars, to more complex behaviour in the probable post main sequence B[e] stars. H...

The C I, Na I D, and Hα lines of the postAGB binary HR 4049 have been studied. Na I D variability results from a photospheric absorption component ([Na/H]=−1.6 ± 0.2) which follows the velocity of the primary and a stationary, non-photospheric component. An emission component is attributed to the circumbinary disc, and an absorption component to mass-loss from the system with a velocity of 5.3±...

In a first of a series of studies of the Hα + [NII] emission from nearby spiral galaxies, we present measurements of Hα + [NII] emission from HII regions in M81. Our method uses large-field-CCD images and long-slit spectra, and is part of the ongoing BeijingArizona-Taipei-Connecticut Sky Survey (the BATC survey). The CCD images are taken with the NAOC 0.6/0.9m f/3 Schmidt telescope at the Xingl...

We present the results of narrow-band Hα+[N II] imaging of the early-type spiral NGC 3593 in combination with a study of the flux radial profiles of the [N II] (λλ 654.80, 658.34 nm), Hα, and [S II] (λλ 671.65, 673.08 nm) emission lines along its major axis. The galaxy is known to contain two counterrotating stellar discs of different size and luminosity. We find that the Hα emission mainly der...