Related papers: A study of lambda Bootis type stars in the wavelen…
We present new infrared photometry for 61 halo and disk stars around the stellar/substellar boundary. These data are combined with available optical photometry and astrometric data to produce color--color and absolute magnitude--color…
CONTEXT. The Lambda Bootis stars are a small spectroscopic subgroup of Population I A-type stars and show significant underabundances of metals. Many are Delta Scuti pulsators. AIMS. HD 210111 was selected for a detailed multisite pulsation…
Context: Hot subdwarf B stars (sdBs) are considered to be core helium-burning stars with very thin hydrogen envelopes situated on or near the extreme horizontal branch (EHB). The formation of sdBs is still unclear as well as the chemical…
We present a study of the abundances and physical conditions in the interstellar gas toward the heavily reddened star HD 192639 [E_(B-V) = 0.64], based on analysis of FUSE and HST/STIS spectra covering the range from 912 to 1361 A. This…
[abridged] The presence of large amounts of dust in the habitable zones of nearby stars is a significant obstacle for future exo-Earth imaging missions. We executed an N band nulling interferometric survey to determine the typical amount of…
Using early data from the Infrared Array Camera (IRAC) on the Spitzer Space Telescope, taken for the Great Observatories Origins Deep Survey (GOODS), we identify and study objects that are well-detected at 3.6um, but are very faint (and in…
In this article the current knowledge of the group of lambda Bootis stars is reviewed. These metal poor objects are quite outstanding compared to other chemically peculiar stars of the upper main sequence. Up to now no theory has been…
We present the first volume-limited sample of spectroscopically confirmed hot subluminous stars out to 500 pc, defined using the accurate parallax measurements from the {\em Gaia} space mission data release 3 (DR3). The sample comprises a…
We present observations of six isolated, pre-main-sequence, intermediate mass stars selected for shallow spectra at submillimeter wavelengths at 1.3, 2.6, 7.0, and 36 millimeters from the IRAM PdBI and the VLA. We analyze the new…
We report spectra obtained with the Spitzer Space Telescope in the wavelength range between 14 microns and 35 microns of 19 nearby main-sequence stars with infrared excesses. The six stars with strong dust emission show no recognizable…
The connection between helium-rich hot subdwarfs of spectral types O and B (He-sdB) has been relatively unexplored since the latter were found in significant numbers in the 1980's. In order to explore this connection further, we have…
We present a mini-survey of Galactic B[e] stars mainly undertaken with the Large Binocular Telescope (LBT). B[e] stars show morphological features with hydrogen emission lines and an infrared excess, attributed to warm circumstellar dust.…
Phosphorus abundances of ~80 apparently bright sharp-lined early-to-late B-type stars on the upper main sequence are determined by applying the non-LTE analysis to the P II line at 6043.084 A, with an aim of getting information on the P…
A significant fraction of nearby young moving group members harbor circumstellar debris dust disks. Due to their proximity and youth, these disks are attractive targets for studying the early evolution of debris dust and planetesimal belts.…
We present results of the analysis of a sample of 22 stars of spectral types from O7 to B5 and luminosity classes I-V for which Spitzer/IRS spectra are available. The IRS spectra of these stars are examined for signs of excess infrared (IR)…
We present evidence for unusually strong Halpha emission in galaxies with spectroscopic redshifts in the range of 3.8<z<5.0, over the Great Observatories Origins Deep Survey (GOODS) fields. Among 74 galaxies detected in the Spitzer IRAC 3.6…
Dramatic deficiencies of Li in the mid-F dwarf stars of the Hyades cluster were discovered by Boesgaard & Tripicco. Boesgaard & King discovered corresponding, but smaller, deficiencies in Be in the same narrow temperature region in the…
The hydrogen-line spectrum of eight lambda Boo type stars is studied. The observed H_delta and H_gamma profiles are compared with Kurucz's theoretical profiles. The existence of weak emission-like details in the cores of five lambda Boo…
We present new mid-infrared spectra for a sample of 15 targets (1 FU Orionis object, 4 Herbig Ae stars, 5 T Tauri stars and 5 Vega type stars), obtained with the TIMMI2 camera at La Silla Observatory (ESO). Three targets are members of the…
We present a series of systematic abundance measurements for a group of hot DA white dwarfs in the temperature range 20,000-75,000K, based on far-UV spectroscopy with STIS on HST, IUE and FUSE. Using our latest heavy element blanketed…