Related papers: Evidence for a companion to BM Gem, a silicate car…
While M dwarfs are the most abundant stars in the Milky Way, there is still large uncertainty about their basic physical properties (mass, luminosity, radius, etc.) as well as their formation environment. Precise knowledge of multiplicity…
Elemental abundances of extrinsic carbon stars provide insight into the poorly understood origin and evolution of elements in the early Galaxy. In this work, we present the results of a detailed spectroscopic analysis of four potential…
Optical-infrared interferometry can provide direct geometrical measurements of the radii of Cepheids and/or reveal unknown binary companions of these stars. Such information is of great importance for a proper calibration of…
We present first results from the Palomar Adaptive Optics Survey of Young Stars conducted at the Hale 5 m telescope. Through direct imaging we have discovered a brown dwarf and two low-mass stellar companions to the young solar-type stars…
During the early stages of star formation, accretion processes such as infall from the envelope and molecular streamers, and ejection of matter through winds and jets take place simultaneously. The Class 0/I binary [BHB2007] 11 shows…
Details of simultaneous photometric and spectroscopic observations of the optical counterpart of the `supersoft' X-ray source 1E 0035.4-7230 (SMC 13) are presented. Although the spectrum is dominated by emission lines of He II, the Balmer…
The nebular circumstellar environments of cool evolved stars are known to harbour a rich morphological complexity of gaseous structures on different length scales. A large part of these density structures are thought to be brought about by…
We report the discovery of one possible neutron star binary ($P_{\rm orb} =$ 0.8666 day) by using the LAMOST low-resolution spectroscopic data. The visible companion is a late A-type dwarf ($T_{\rm eff} = 7900 \pm 200$ K; log$g$ $=$…
Recent exo-planetary surveys reveal that planets can orbit and survive around binary stars. This suggests that some fraction of young binary systems which possess massive circumbinary disks (CB) may be in the midst of planet formation.…
Binary companions to asymptotic giant branch (AGB) stars are an important aspect of their evolution. Few AGB companions have been detected, and in most cases it is difficult to distinguish between main-sequence and white dwarf companions.…
Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of Be stars owe their rapid rotation to mass and angular-momentum transfer in…
The B[e] phenomenon is manifested by a heterogeneous group of stars surrounded by gaseous and dusty circumstellar envelopes with similar physical conditions. Among these stars, the FS CMa-type objects are suspected to be binary systems,…
(Abridged) Low-luminosity, active star-forming blue compact galaxies (BCGs) are excellent laboratories for investigating the process of star formation on galactic scales and probing the interplay between massive stars and the surrounding…
We present HST ultraviolet spectroscopy of the white dwarfs PG0843+516, PG1015+161, SDSS1228+1040, and GALEX1931+0117, which accrete circumstellar planetary debris formed from the destruction of asteroids. Combined with optical data, a…
Observations of planetary material polluting the atmospheres of white dwarfs are an important probe of the bulk composition of exoplanetary material. Medium- and high-resolution optical and ultraviolet spectroscopy of seven white dwarfs…
Context. The star HD 87643, exhibiting the "B[e] phenomenon", has one of the most extreme infrared excesses for this object class. It harbours a large amount of both hot and cold dust, and is surrounded by an extended reflection nebula.…
Barium (Ba) stars are chemically peculiar stars that show enhanced surface abundances of heavy elements produced by the slow-neutron-capture process, the so-called s-process. These stars are not sufficiently evolved to undergo the s-process…
We present numerical hydrodynamical modeling of the effects of a giant planet or brown dwarf companion orbiting within the extended atmosphere and wind formation zone of an approximately solar-mass Mira variable star. The large-scale,…
We report the discovery of a new totally-eclipsing binary (RA=06:40:29.11; Dec=+38:56:52.2; J=2000.0; Rmax=17.2 mag) with an sdO primary and a strongly irradiated red dwarf companion. It has an orbital period of Porb=0.187284394(11) d and…
BG Gem is an eclipsing binary with a 91.6-day orbital period. The more massive primary component does not seem to show absorption lines in the spectrum, while the less massive secondary is thought to be a K-type star, possibly a supergiant.…