相关论文: K-band spectra of selected post-AGB candidates

We present a high resolution detailed abundance analysis for a sample of six post-AGB candidate stars, five of them had not been studied spectroscopically in the optical region. All the analyzed objects are IRAS sources identified as…

The first high-resolution (R~50,000) optical spectrum of the B-type star, LS III +52 24, identified as the optical counterpart of the hot post-AGB candidate IRAS 22023+5249 (I22023) is presented. We report the detailed identifications of…

We present 2 to 2.4 micron integral field spectroscopy of a sample of hot post-AGB stars with early-B spectral types, using the NIFS instrument on Gemini North. These stars are just beginning to ionize their immediate environments and turn…

We investigate the infrared properties of the IRAS sources not confirmed as PNe in Van de Steene & Pottasch (1993). We observed 28 objects in the N-band of which 20 were detected and 5 were resolved. We obtained medium resolution Br_gamma…

Aims: To investigate the first high resolution optical spectrum of the B-type star, LS III +52 24, identified as the optical counterpart of the hot post-AGB candidate IRAS 22023+5249 (I22023). Methods: We carried out detailed…

Spectral analyses of H-deficient post-AGB stars have shown that a small group of four extremely hot objects exists which have almost pure He absorption-line spectra in the optical. These are classified as O(He) stars. For their evolution…

Hot (OB) post-AGB stars are immediate progenitors of planetary nebulae (PNe). Very few hot post-AGB stars are known. Detecting new hot post-AGB candidates and follow-up multiwavelength studies will enable us to further understand the…

From an analysis of absorption lines in the high resolution spectra we have derived the radial velocities, stellar parameters (Teff, gravity, wind-strength parameter logQ and projected rotational velocity) and abundances (C, N, O, and Si )…

Aims: We study the optical spectral properties of a sample of stars showing far infrared colours similar to those of well-known planetary nebulae. The large majority of them were unidentified sources or poorly known in the literature at the…

The observations and comprehensive study of intermediate initial mass stars at the late stages of evolution, and after the asymptotic giant branch (AGB) in particular, are of crucial importance to identify the common properties for the…

Non-variable OH/IR stars are thought to have just left the asymptotic giant branch (AGB) phase. In this conventional picture, they must still show strong circumstellar extinction caused by the dust ejected during the AGB phase, and the…

The high-resolution ($R\sim48\,000$) optical spectrum of the B-type supergiant LS 5112, identified as the optical counterpart of the post-AGB candidate IRAS 18379-1707, is analysed. We report the detailed identifications of the observed…

We have derived elemental abundances for a sample of nine IRAS sources with colours similar to those of post-AGB stars. For IRAS 01259+6823, IRAS 05208-2035, IRAS 04535+3747 and IRAS 08187-1905 this is the first detailed abundance analysis…

Analysis of the low resolution UV(IUE) spectra of 15 hot post-AGB candidates is presented. The UV(IUE) spectra of 10 stars suggest partial obscuration of the hot stars due to circumstellar dust. The reddened continua of these 10 stars were…

We present the basic properties of the multipolar post-AGB star IRAS 16594-4656, and discuss in particular its near infrared spectrum which shows shock excited H2 and [Fe II] emission lines.

Using 766 compact objects from a survey of the galactic Plane in the 1612-MHz OH line, new light is cast on the infrared properties of evolved stars on the TP-AGB and beyond. The usual mid-infrared selection criteria, based on IRAS colours,…

To search for and study the instabilities in the atmospheres of selected post-AGB stars, we have performed a long-term high-resolution spectroscopy (R=60000) with the spectrograph NES of the 6-meter BTA telescope. Low-amplitude pulsations,…

We have monitored over a ten-year interval the light variations of five evolved stars with very large mid-infrared excesses. All five objects appear to have oxygen-rich or mixed oxygen-rich and carbon-rich chemistries. They all vary in…

We present a detailed chemical analysis on the basis of high-resolution, high signal-to-noise optical spectra of two post-AGB objects IRAS 22223+4327 and IRAS 04296+3429. Both display the unidentified $21 \mu m$ feature in their IR-spectra.…

Detailed atmospheric abundances have been calculated for a sample of A-G supergiant stars with IR fluxes and/or high galactic latitudes. HD 172481 and HD 158616 show clear indications of being post-AGB stars that have experienced third…