We report our attempts to detect and confirm a narrow moving component in the Hα emission line of LS I+61303. The existence of this spectral feature was already suspected in the past. As a result, we find that this component does exist and that its radial velocity varies in agreement with the radio period of the system. We interpret it tentatively as due to a denser region, or bulge, orbiting n...

During the initial data reduction of the Wisconsin H-Alpha Mapper (WHAM) Hα Sky Survey, we have discovered several very long (∼ 30 • –80 •) filaments superimposed on the diffuse Hα background. These features have no clear correspondence to the other phases of the interstellar medium revealed by 21 cm, X-ray, IR, or radio continuum surveys, and they have no readily identifiable origin or source ...

In this study we test the possibility that the asymmetry in the profiles of the Hα and Ca ii K lines in red giant stars is due to the presence of an active chromosphere rather than to mass loss. To this end, we compare line profiles computed using relevant model chromospheres to profiles of the Hα and Ca ii K lines observed in five red giant stars of the globular cluster NGC 2808. The spectra w...

Abstract: Let X,Y,B be three independent random variables such that X has the same distribution function as Y B. Assume that B is a beta random variable with positive parameters α, β and Y has distribution function H with H(0) = 0. Pakes and Navarro (2007) show under some mild conditions that the distribution function Hα,β of X determines H . Based on that result we derive in this paper a recur...

Recently completed Hα surveys of large portions of the sky can be used to create maps of the free-free intensity distribution at high Galactic latitude that are independent of the spectral fits to the CMB data. This provides an opportunity to test the accuracy of the spectral fitting procedures and to search for other sources of Galactic forground contamination that could be confused spectrally...

We report the discovery of a new Hi ring around the S0 galaxy NGC 1533. The ring orbits at a radius of 35 kpc, well outside the optical extent of the galaxy. We have conducted N-body/SPH numerical simulations to show this Hi ring could be the merger remnant of a tidally destroyed galaxy. We find no optical component associated with the Hi ring. However, observations hint at Hα emission associat...

We present time-resolved spectroscopy of the Be star HD 76534, which was observed to have an Hα outburst in 1995, when the line went from photospheric absorption to emission at a level of more than two times the continuum within 2.5 hours. To investigate the short-term behaviour of the spectrum of HD 76534 we have obtained 30 spectra within two hours real-time and searched for variations in the...

We have obtained optical CCD spectroscopy along the major axes of 22 nearby spiral galaxies of Sb and Sc types in order to analyze their rotation curves. By subtracting the stellar continuum emission, we have obtained position velocity (PV) diagrams of the Hα and [NII] lines. We point out that the Hα line is often superposed by a broad stellar absorption feature (Balmer wind) in the nuclear reg...