Related papers: Distances of Dwarf Carbon Stars
Results are presented for a Hubble Space Telescope Advanced Camera for Surveys high-resolution imaging campaign of 90 white dwarfs with known or suspected low mass stellar and substellar companions. Of the 72 targets which remain candidate…
While the first binary post-AGB stars were serendipitously discovered, the distinct characteristics of their Spectral Energy Distribution (SED) allowed us to launch a more systematic search for binaries. We selected post-AGB objects which…
We present an overview of the sample of northern hemisphere white dwarfs within 40 pc of the Sun detected from $Gaia$ Data Release 2 (DR2). We find that 521 sources are spectroscopically confirmed degenerate stars, 111 of which were first…
The destiny of planetary systems through the late evolution of their host stars is very uncertain. We report a metal-rich gas disk around a moderately hot and young white dwarf. A dynamical model of the double-peaked emission lines…
Fluorine (19F) abundances (or upper limits) are derived in six extragalactic AGB carbon stars from the HF(1-0) R9 line at 2.3358 mu in high resolution spectra. The stars belong to the Local Group galaxies LMC, SMC and Carina dwarf…
In an earlier paper, we determined the morphological types of galaxies in the Coma Cluster using data from the HST/ACS Coma Cluster treasury survey. We found that of the 132 members, 51 are non dwarfs and 81 are dwarfs. We define dwarfs to…
Measurements of [C/Fe], [Ca/H], and [Fe/H] have been derived from Keck I LRISb spectra of 35 giants in the Draco dwarf spheroidal galaxy. The iron abundances are derived by a spectrum synthesis modeling of the wavelength region from 4850 to…
We consider three samples of O- and B-type stars from the solar neighborhood 0.6--4 kpc for which we have taken the distances, line-of-sight velocities, and proper motions from published sources. The first sample contains 120 massive…
We present elemental abundances of 13 microlensed dwarf and subgiant stars in the Galactic bulge, which constitute the largest sample to date. We show that these stars span the full range of metallicity from Fe/H=-0.8 to +0.4, and that they…
Spectra for stars located redward of the fiducial red giant branches of the Ursa Minor and Draco dwarf spheroidal galaxies have been obtained with the Hobby-Eberly telescope and the Marcario Low Resolution Spectrometer. From a comparison of…
A multi-epoch, absolute-fluxed spectral atlas extending from about 3200 to 9000 Ang is presented for 130 symbiotic stars, including members of the LMC, SMC and Draco dwarf galaxies. The fluxes are accurate to better than 5% as shown by…
It remains challenging to systematically survey nearby diffuse dwarf galaxies and address the formation mechanism of this population distinguishing from regular ones. We carry out a pilot search for these galaxies in the COSMOS field using…
The search for binarity in AGB stars is of critical importance for our understanding of how planetary nebulae acquire the dazzling variety of aspherical shapes which characterises this class. However, detecting binary companions in such…
We present precise photometry and spectroscopy for 23 candidate spectrophotometric standard white dwarfs. The selected stars are distributed in the Northern hemisphere and around the celestial equators and are all fainter than r ~ 16.5 mag.…
We report the results of a survey of the region within 40 arcmin of NGC 891, a nearby nearly perfectly edge-on spiral galaxy. Candidate "non-stars" with diameters greater than 15 arcsec were selected from the GSC 2.3.2 catalog and…
Using LAMOST spectroscopic data, we find a strong signal of a comoving group of stars in the constellation of Draco. The group, observed near the apocenter of its orbit, is 2.6 kpc from the Sun with a metallicity of -0.64 dex. The system is…
We construct from Gaia eDR3 an extensive catalog of spatially resolved binary stars within $\approx$ 1 kpc of the Sun, with projected separations ranging from a few au to 1 pc. We estimate the probability that each pair is a chance…
If dwarf galaxies are primeval objects in the Universe, as hierarchical galaxy formation scenarios predict, they should show traces of their old stellar populations, perhaps distributed in extended, differentiated structures. The working…
We present new Chandra X-ray Observatory and Hubble Space Telescope observations of eight optically selected broad-line AGN candidates in nearby dwarf galaxies ($z<0.055$). Including archival Chandra observations of three additional…
Hipparcos astrometric binaries were observed with the NICI adaptive optics system at Gemini-S, completing the work of Paper I (Tokovinin et al. 2012). Among the 65 F, G, K dwarfs within 67pc of the Sun studied here, we resolve 18 new…