We present echelle long-slit optical spectra of a sample of objects evolving off the AGB, most of them in the pre-planetary nebula (pPN) phase, obtained with the ESI and MIKE spectrographs at Keck-II and Magellan-I, respectively. The total wavelength range covered with ESI (MIKE) is ~3900 to 10900 A (~3600 to 7200A). In this paper, we focus our analysis mainly on the Halpha profiles. Prominent Halpha emission is detected in half of the objects, most of which show broad Halpha wings (up to ~4000 km/s). In the majority of the Halpha-emission sources, fast, post-AGB winds are revealed by P-Cygni profiles. In ~37% of the objects Halpha is observed in absorption. In almost all cases, the absorption profile is partially filled with emission, leading to complex, structured profiles that are interpreted as an indication of incipient post-AGB mass-loss. All sources in which Halpha is seen mainly in absorption have F-G type central stars, whereas sources with intense Halpha emission span a larger range of spectral types from O to G. Shocks may be an important excitation agent of the close stellar surroundings for objects with late type central stars. Sources with pure emission or P Cygni Halpha profiles have larger J-K color excess than objects with Halpha mainly in absorption, which suggests the presence of warm dust near the star in the former. The two classes of profile sources also segregate in the IRAS color-color diagram in a way that intense Halpha-emitters have dust grains with a larger range of temperatures. (abridged)
Gemini Observatory's northern and southern telescopes are both presently being outfitted with facility mid-infrared imagers/spectrometers. This will allow observers the unique opportunity to apply to one observatory for all-sky spectroscopic access in the mid-infrared with the light gathering power of 8-meter telescopes. Gemini South has recently commissioned the Thermal-Region Camera and Spectrograph (T-ReCS) and is now available to perform queue observations for the community. T-ReCS is capable of low-resolution long-slit spectroscopy of R~100 near 10 and 20 um, and medium-resolution long-sl…
The World Space Observatory Ultraviolet (WSO/UV) is a multi-national project grown out of the needs of the astronomical community to have future access to the UV range. WSO/UV consists of a single UV telescope with a primary mirror of 1.7m diameter feeding the UV spectrometer and UV imagers. The spectrometer comprises three different spectrographs, two high-resolution echelle spectrographs (the High-Resolution Double-Echelle Spectrograph, HIRDES) and a low-dispersion long-slit instrument. Within HIRDES the 102-310nm spectral band is split to feed two echelle spectrographs covering the UV range…
We discuss the design and performance of TEXES, the Texas Echelon Cross Echelle Spectrograph. TEXES is a mid-infrared (5-25 um) spectrograph with several operating modes: high-resolution, cross-dispersed with a resolving power of R=100,000, 0.5% spectral coverage, and a ~1.5 by 8" slit; medium-resolution long-slit with R~15,000, 0.5% coverage, and a ~1.5 by 45" slit; low-resolution long-slit with (delta lambda)~0.004 um, 0.25 um coverage, and a ~1.5 by 45" slit; and source acquisition imaging with 0.33" pixels and a 25 by 25" field of view on a 3m telescope. TEXES has been used at the McDonald…
We present off-nuclear spectra of 3 radio loud QSO's, 3C249.1, 3C273 and 3C323.1., taken with the echellette spectrograph and imager (ESI) at Keck observatory. From these spectra we have extracted the spatial profile along the slit of the [OIII], $λ= \textsf{5007}$ line. Fitted Gaussian distributions to each of these profiles show emission-line gas out to several tens of kiloparsecs from the galaxy nucleus. Most observations show several gas components at distinct velocities and velocity dispersions, much of which is above the escape velocity for any resonable mass galaxy. In addition, we show…
The bulge contains the most chemically evolved old stellar population in the Milky Way. Thanks to microlensing, it is now possible to obtain high resolution echelle spectra of bulge stars near the main sequence turn-off, and study the abundance of elements that are affected by stellar evolution, such as lithium. We have observed with the HIRES spectrograph on the Keck I 10m telescope the source star of the MACHO microlensing event 97BLG45 while it was magnified by about 1 magnitude. Here we report the detection of the Li I line at λ6707.8 Åin the echelle spectrum of this star, and measure the …
We present a method estimating the atmospheric parameters Teff, log g, [Fe/H] for stars observed, even at low signal to noise ratio, with the echelle spectrograph ELODIE on the 193cm telescope at Observatoire de Haute-Provence. The method relies on the least-square comparison of the spectrum of a target star to a library of 211 spectra of reference stars for which the atmospheric parameters are well known and which were observed with the same instrument. In order to obtain a meaningful comparison between target and reference spectra, all features which are not intrinsic to the objects must be …
We obtain high-resolution echelle spectra of evolved Hipparcos stars within 100 parsec for detailed abundance analysis. We are particularly interested in subgiants because their ages can be derived accurately. Here, we present preliminary results for 10 subgiants and discuss the future work for this project. Our main scientific interest is to incorporate our results to constrain the star formation history in the solar neighborhood.
The three-dimensional Monte Carlo photoionization code Mocassin has been applied to construct a realistic model of the planetary nebula NGC 3918. Three different geometric models were tried. The effects of the interaction of the diffuse fields coming from two adjacent regions of different densities were investigated. These are found to be non-negligible, even for the relatively uncomplicated case of a biconical geometry. We found that the ionization structure of low ionization species near the boundaries is particularly affected. It is found that all three models provided acceptable matches to…
Long-slit echelle spectra reveal bright extended emission from the K I lambda7699 resonance line in the reflection nebula surrounding the extreme red supergiant VY Canis Majoris. The central star has long been known for its unusually-bright K I emission lines, but this is the first report of intrinsic emission from K I in the nebula. The extended emission is not just a reflected spectrum of the star, but is due to resonant scattering by K atoms in the outer nebula itself, and is therefore a valuable probe of the kinematics and geometry of VY CMa's circumstellar environment. Dramatic velocity s…
An optical spectrum of the Elson et al. (1998) candidate luminous white dwarf in the young LMC cluster NGC1818 shows conclusively that it is not a degenerate star. A model atmosphere fit gives T=31,500K and log g=4.4, typical of a garden-variety main sequence B star. However, if it is a true LMC member then the star is under-luminous by almost three magnitudes. Its position in the cluster colour-magnitude diagram also rules out the possibility that this is an ordinary B star. The luminosity is, however, consistent with a ~0.5 solar mass post-AGB or post-EHB object, although if it has evolved v…
We present [OIII]500.7nm and Halpha+[NII] images and long-slit, high resolution echelle spectra in the same spectral regions of Sa2--237, a possible bipolar planetary nebula. The image shows a bipolar nebula of about 34" extent, with a narrow waist, and showing strong point symmetry about the central object, indicating it's likely binary nature. The long slit spectra were taken over the long axis of the nebula, and show a distinct ``eight'' shaped pattern in the velocity--space plot, and a maximum projected outflow velocity of V=106km/s, both typical of expanding bipolar planetary nebulae. By …
High spatial and spectral resolution spectroscopy of the OH/IR supergiant VY CMa and its circumstellar ejecta reveals evidence for high mass loss events from localized regions on the star occurring over the past 1000 years. The reflected absorption lines and the extremely strong K I emission lines show a complex pattern of velocities in the ejecta. We show that the large, dusty NW arc, expanding at 50 km/sec with respect to the embedded star, is kinematically distinct from the surrounding nebulosity and was ejected about 400 years ago. Other large, more filamentary loops were probably expelled…
We present new imaging and spectroscopy of the post-red supergiant binary AFGL 4106. Coronographic imaging in H-alpha reveals the shape and extent of the ionized region in the circumstellar envelope (CSE). Echelle spectroscopy with the slit covering almost the entire extent of the CSE is used to derive the physical conditions in the ionized region and the optical depth of the dust contained within the CSE. The dust shell around AFGL 4106 is clumpy and mixed with ionized gas. H-alpha and [N II] emission is brightest from a thin bow-shaped layer just outside of the detached dust shell. On-going …
In order to investigate whether the brightest globular clusters (GCs) in the giant elliptical galaxies are similar to the less luminous GCs like those found in Local Group galaxies, we study the velocity dispersion and structural parameter correlations of a sample of bright GCs in the nearest gE galaxy NGC 5128. UVES echelle spectrograph on the ESO VLT, and EMMI on the ESO NTT were used to obtain high resolution spectra of bright GCs in NGC 5128. The velocity dispersions were obtained for all the targets. The structural parameters were either taken from the existing literature, or derived from…
Dedicated to spectroscopic and imaging observations of the ultraviolet sky, the World Space Observatory for Ultraviolet Project is a Russia led international collaboration presently involving also China, Germany, Italy, Spain and Ukraine. The mission consists of a 1.7m telescope able to perform: a) high resolution (R greater than 60000) spectroscopy by means of two echelle spectrographs covering the 103-310 nm range; b) long slit (1x75 arcsec) low resolution (R about 1500-2500) spectroscopy using a near-UV channel and a far-UV channel to cover the 102-310nm range; c) deep UV and diffraction li…
The rapidly oscillating Ap stars are of importance for studying the atmospheric structure of stars where the process of chemical element diffusion is significant. We have performed a survey for rapid oscillations in a sample of 9 luminous Ap stars, selected from their location in the colour-magnitude diagram as more evolved main-sequence Ap stars that are inside the instability strip for rapidly oscillating Ap (roAp) stars. Until recently this region was devoid of stars with observed rapid pulsations. We used the VLT UV-Visual Echelle Spectrograph (UVES) to obtain high time resolution spectros…
Eta Carinae is one of the most extreme cases of a Luminous Blue Variable star. A bipolar nebula of 17" size surrounds the central object. Even further out, a large amount of filamentary material extends to a distance of 30" or about 0.3 pc. In this paper we present a detailed kinematic and morphological analysis of some outer filaments in this nebula which we call strings. All strings are extremly long and narrow structures. We identified 5 strings which have sizes of 0.058 to 0.177 pc in length and a width of only 0.002 pc. Using high-resolution long-slit echelle spectroscopy it was found tha…
An analysis of high-resolution Anglo-Australian Telescope (AAT)/ University College London Echelle Spectrograph (UCLES) optical spectra for the ultraviolet (UV)-bright star ROA 5701 in the globular cluster omega Cen (NGC 5139) is performed, using non-local thermodynamic equilibrium (non-LTE) model atmospheres to estimate stellar atmospheric parameters and chemical composition. Abundances are derived for C, N, O, Mg, Si and S, and compared with those found previously by Moehler et al. We find a general metal underabundance relative to young B-type stars, consistent with the average metallicity …
Integral-field spectroscopy of molecular hydrogen in the optical wavelength region and complementary long-slit near-infrared spectroscopy are presented towards HH91A.The detection of some 200 H_2 lines arising from ro-vibrational levels up to v'=8 ranging between 7700A and 2.3 microns is reported. The emission arises from thermally excited gas where the bulk of the material is at 2750 K and where 1% is at 6000 K. The total column density of shocked gas is N(H_2) = 10^{18} cm^{-2}. Non-thermal excitation scenarios such as UV-fluorescence do not contribute to the excitation of H_2 towards HH91A.…
Accurate emission line fluxes from planetary nebulae (PNe) provide important constraints on the nature of the final phases of stellar evolution. Large, evolved PNe may trace the latest stages of PN evolution, where material from the AGB wind is returned to the interstellar medium. However, the low surface brightness and spatially extended emission of large PNe have made accurate measurements of line fluxes difficult with traditional long-slit spectroscopic techniques. Furthermore, distinguishing these nebulae from HII regions, supernova remnants, or interstellar gas ionized by a hot, evolved s…
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 identifications of the observed absorption and emission features in the high resolution spectrum (4290 - 9015 A) of I22023 obtained with the Utrecht Echelle Spectrograph on the 4.2m William Herschel Telescope. Using Kurucz's WIDTH9 program and the spectrum synthesis code, SYNSPEC, we determined the atmospheric parameters and abundances. The photospheric abundances were de…
The B[e]/K binary system MWC 623 was reinvestigated using new spectroscopic observations. The absorption lines of the K and the B star do not exhibit any significant radial velocity variations over a time interval of 14 years. The spectral classification using a recent echelle spectrum yielded spectral types of K2II-Ib and B4III. The luminosity class of the K star gives an estimate of the distance towards MWC 623 of 2.4(+1.4/-0.9) kpc. This is consistent with the kinematic distance of 2.0(+0.6/-0.3) kpc. The masses derived from the locations of the binary components in the H-R diagram are 7+-1…
The very massive star, Eta Carinae, is enshrouded in an unusual complex of stellar ejecta, which is highly depleted in C and O, and enriched in He and N. This circumstellar gas gives rise to distinct absorption components corresponding to at least 20 different velocities along the line-of-sight. The velocity component at -513 kms-1 exhibits very low ionization with predominantly neutral species of iron-peak elements. Our statistical equilibrium/photoionization modeling indicates that the low temperature (T = 760 K) and high density (n_H=10^7 cm^-3) of the -513 kms-1 component is conducive to m…
Deep long-slit spectroscopic data are presented for a sample of 14 3CR radio galaxies at redshift z ~ 1, previously studied in detail using the Hubble Space Telescope, the Very Large Array, and UKIRT. Analysis of the [OII] 3727 emission line structures at 5 Ang spectral resolution is carried out to derive the kinematic properties of the emission line gas. In line with previous, lower resolution, studies, a wide variety of kinematics are seen, from gas consistent with a mean rotational motion through to complex structures with velocity dispersions exceeding 1000 kms. The data confirm the presen…
Aims. We intend to spatially and spectrally resolve the [O I] emission region in two nearby Herbig stars. Methods. We present high-resolution (R = 80,000) VLT/UVES echelle spectra of the [O I] 6300A line in the Herbig Ae/Be stars HD 97048 and HD 100546. Apart from the spectral signature, also the spatial extent of the [O I] emission region is investigated. For both stars, we have obtained spectra with the slit positioned at different position angles on the sky. Results. The [O I] emission region of HD 100546 appears to be coinciding with the dust disk, its major axis located at 150+/-11 degree…
We present HST spectroscopy and imaging, along with new ground-based spectroscopy and ROSAT HRI imaging, of the He II emitting nebula N44C and its ionizing star. A GHRS spectrogram of the ionizing star yields a spectral type of about O7 for the star. The lack of P Cygni profiles for Si IV and C IV indicates that the star is not a supergiant. The nebular abundances in the ionized gas are consistent with average abundances for LMC H II regions, with the possible exception that nitrogen may be enhanced. Enrichment by a former evolved companion star is not evident. A long-slit echelle spectrogram …
We have carried out near-IR/optical observations to examine star formation toward a bright-rimmed cometary globule (BRC37) facing the exciting star(s) of an HII region (IC1396) containing an IRAS source, which is considered to be an intermediate-mass protostar. With slit-less spectroscopy we detected ten H_alpha emission stars around the globule, six of which are near the tip of the globule and are aligned along the direction to the exciting stars. There is evidence that this alignment was originally towards an O9.5 star, but has evolved to align towards a younger O6 star when that formed. Nea…
We present evidence that some of the compact, luminous, young star clusters recently discovered through images taken with the Hubble Space Telescope (HST) have masses comparable to those of old Galactic globular clusters. The "super star cluster" in the center of the nearby amorphous galaxy NGC 1705 has been observed with high dispersion at optical wavelengths using the HIRES echelle spectrograph on the Keck 10 m telescope. Numerous weak metal lines arising from the atmospheres of cool supergiants have been detected in the integrated spectrum, permitting a direct measurement of the line-of-sig…
The relation between tidal interactions, starbursts, and the onset and/or fueling of active galactic nuclei (AGN) is a matter of debate. I Zw 1 is considered as the prototypical narrow-line Seyfert 1 galaxy (NLS1) and as one of the closest quasi-stellar objects (QSOs). With a clear spiral host and a small companion galaxy to the west, I Zw 1 is a possible example of minor-merger-related nuclear activity. This study investigates possible signs of a relation between merger process, star formation activity, and AGN properties in the case of I Zw 1. The morphology of I Zw 1 and nearby sources is i…
