Related papers: Optical spectroscopy of Cyg X-1
Optical spectra were obtained of the optical counterpart of the high latitude soft X-ray transient XTE J1118+480 near its quiescent state with the new 6.5 m MMT and the 4.2 m WHT. The spectrum exhibits broad, double-peaked, emission lines…
We present results of nearly six years of spectroscopic observations of the B[e] star V2028 Cyg. The presence of the cold-type absorption lines combined with a hot-type spectrum indicate the binarity of this object. Since B[e] stars are…
The knowledge of the spectral state of a black hole is essential for the interpretation of data from black holes in terms of their emission models. Based on pointed observations of Cyg X-1 with the Rossi X-ray timing Explorer (RXTE) that…
The black hole binary Cygnus X-1 was observed in late-2012 with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku, providing spectral coverage over the ~1-300 keV range. The source was in the soft state with a multi-temperature…
We present the results of a search for optical counterparts of ultraluminous X-ray source (ULX) X-1 in the nearby galaxy NGC 2500 by using archival images taken with the Hubble Space Telescope ({\it HST}) Wide Field Camera (WFC3)/UVIS. Four…
State-of-the-art techniques to identify H\alpha emission line sources in narrow-band photometric surveys consist of searching for H\alpha excess with reference to nearby objects in the sky (position-based selection). However, while this…
We present new HI observations of Hoag's Object obtained with the Westerbork Synthesis Radio Telescope (WSRT). The data show that the luminous optical ring around the elliptical body has a bright HI counterpart that shares the kinematical…
Coordinated observations X-ray+optical observations of two southern X-ray binaries, the black hole candidate XTE J1746-321 and the neutron star accreter Cir X-1 (a `microquasar') are reported. With a photon counting optical photometer on…
The point-like X-ray source HLX-1, close to the S0 galaxy ESO 243-49, is one the strongest intermediate-mass black hole candidates, but the nature of its counterpart is still puzzling. By means of N-body/smoothed particle hydrodynamics…
DH Cephei is a prominent O+O-type binary system in the NGC 7380 open cluster. Our high-precision multi-band polarimetry demonstrates synchronous linear polarization variations with the orbital period. Using Stokes parameters, we derived the…
We present medium-resolution optical spectroscopy with the SOAR telescope of the O star secondary of the high-mass gamma-ray binary 1FGL J1018.6-5856 to help determine whether the primary is a neutron star or black hole. We find that the…
Stellar-mass black holes have been detected by radial-velocity observations in star/black hole binaries. These allow only the determination of the mass function. Tracking the astrometric orbits of the visible components of the star/black…
Using the HiVIS spectropolarimeter built for the Haleakala 3.7m AEOS telescope, we have obtained a large number of high precision spectropolarimetrc observations (284) of Herbig AeBe stars collected over 53 nights totaling more than 300…
Using infrared spectra of the z = 1.693 quadruply lensed quasar HE0435-1223 acquired in 2009 with the spectrograph SINFONI at the ESO Very Large Telescope, we have detected a clear microlensing effect in images A and D. While microlensing…
We present results from a 20 ksec RXTE observation of the black hole candidate Cyg X-1. We apply self-consistent accretion disk corona models to these hard state data and show that Comptonization in a spherical corona irradiated by soft…
X-ray reflection spectra are an important component in the X-ray spectra of many active galactic nuclei and Galactic black hole candidates. It is likely that reflection takes place from highly ionized surfaces of the accretion disc in some…
High-resolution optical spectra (UES/WHT) of the extreme metal-poor post-AGB star HR4049 were obtained at four different orbital phases. The spectra cover the wavelength region from 3650ang to 10850ang at a resolution of R=5.2x10^4. These…
The emission-line Be star HD 215227 lies within the positional error circle of the newly identified gamma-ray source AGL J2241+4454. We present new blue spectra of the star, and we point out the morphological and variability similarities to…
We report results from a 30 ks observation of Cygnus X-1 with the High Energy Transmission Grating Spectrometer (HETGS) on board the {\em Chandra X-ray Observatory}. Numerous absorption lines were detected in the HETGS spectrum. The lines…
We have carried out a spectroscopic survey of several B, Be, and shell stars in optical and near-infrared regions. Line profiles of the H-alpha line and of selected Fe II and O I lines are presented.