Related papers: The SW Sex enigma
We present a rest-UV selected sample of 32 lensed galaxies at $z\sim 2$ observed with joint Keck/LRIS rest-UV and Keck/MOSFIRE rest-optical spectra behind the clusters Abell 1689, MACS J0717, and MACS J1149. The sample pushes towards the…
Chemical abundances studies of cataclysmic variables have revealed high nitrogen to carbon ratios in a number of of cataclysmic variable white dwarfs (based on ultraviolet emission and absorption lines), as well as possible carbon…
We investigated the temporal and spectral features of $\gamma$ Cassiopeiae's X-ray emission within the context of the white dwarf accretion hypothesis. We find that the variabilities present in the X-ray data show two different signals, one…
We address the physical nature of subdwarf A-type (sdA) stars and their possible link to extremely low mass (ELM) white dwarfs (WDs). The two classes of objects are confused in low-resolution spectroscopy. However, colors and proper motions…
White dwarfs with emission lines from gaseous debris discs are among the rarest examples of planetary remnant hosts, but at the same time they are key objects for studying the final evolutionary stage of planetary systems. Making use of the…
We present low-resolution phase-resolved spectra of the polar MT Dra during its high states in 2006 and 2009. Balmer series, He I and He II 4686 \AA\ emission lines have complex shapes and show similar profile variations over an orbital…
We present a composite light-curve model of the symbiotic nova PU Vul (Nova Vulpeculae 1979) that shows a long-lasted flat optical peak followed by a slow decline. Our model light-curve consists of three components of emission, i.e., an…
Nova V5116 Sgr 2005 No. 2, discovered on 2005 July 4, was observed with XMM-Newton in March 2007, 20 months after the optical outburst. The X-ray spectrum showed that the nova had evolved to a pure supersoft X-ray source, indicative of…
High-resolution observations in the region, centered at 4400 \AA\ and those of the lines HeII 4686, Hbeta and HeI 6678 of the spectrum of the symbiotic binary Z And were performed during its outburst in 2006. The line Hbeta had additional…
We present differential photometry of the cataclysmic variable star SW Sextantis. A time series analysis was performed in search of superhumps in the accretion disk of this star, which is the prototype of a class of cataclysmic variables,…
Classical novae are runaway thermonuclear burning events on the surfaces of accreting white dwarfs in close binary star systems, sometimes appearing as new naked-eye sources in the night sky. The standard model of novae predicts that their…
We have selected three nova-like variables at the long period extreme of nova-like orbital periods: V363 Aur, RZ Gru and AC Cnc, all with IUE archival far ultraviolet spectra. All are UX UMa type nova-like variables and all have $P_{orb} >…
The origin of the bright and hard X-ray emission flux among the gamma Cas subgroup of B-emission line (Be) stars may be caused by gas accretion onto an orbiting white dwarf (WD) companion. Such Be+WD binaries are the predicted outcome of a…
Deep H$\alpha$ images of a faint emission complex 4.0 x 5.5 degrees in angular extent and located far off the Galactic plane at l = 70.0 degrees, b=-21.5 degrees reveal numerous thin filaments suggestive of a supernova remnant's shock…
Following on our initial absorption-line analysis of fifteen novae spectra we present additional evidence for the existence of two distinct components of novae ejecta having different origins. As argued in Paper I one component is the…
The Be star $\pi$ Aquarii shows peculiar $\gamma$ Cas-type X-ray emission, likely caused by its outer disk interacting with a low-mass companion, probably a white dwarf. We study the long-term variability of its optical spectra to derive…
We present VLT spectroscopy and NTT photometry of the faint cataclysmic binary SDSS J003941.06+005427.5. This object shows triple-peaked H-alpha emission with all three peaks variable in both strength and velocity. We measure an orbital…
Using the latest stellar evolution models, theoretical stellar spectra, and a compilation of observed emission line strengths from Wolf-Rayet (WR) stars, we construct evolutionary synthesis models for young starbursts. We explicitly…
We present optical and near-infrared spectroscopy of WISEA J061543.91$-$124726.8, which we rediscovered as a high motion object in the AllWISE survey. The spectra of this object are unusual; while the red optical ($\lambda >$ 7,000 \AA) and…
Photometric and spectroscopic observations reveal the Sloan Digital Sky Survey cataclysmic variable SDSS J132723.39+652854.2 to be a likely SW Sex star with an orbital period of P = 3.28 hours. The Sloan Digital Sky Survey spectrum shows…