STELLAR ASTROPHYSICS WITH THE WORLD'S LARGEST TELESCOPES: First International Workshop on Stellar Astrophysics with the World's Largest Telescopes
752(2005); http://dx.doi.org/10.1063/1.1893326View Description Hide Description
We briefly describe the Hobby‐Eberly Telescope (HET) and its present status and give several examples of successful stellar astrophysics programs. The HET was primarily driven by a science mission of conducting spectroscopic surveys. In addition the HET’s unique design derives from considering that telescopes are largely used for exposure times of an hour or less at moderate zenith distances and modest image quality that is based on median site seeing which is consistent with a survey mission. We present results from planet searches, large radial velocity surveys, and Sloan Digital Sky Survey follow up programs in this context. The queue‐scheduled nature of the HET makes it especially effective at synoptic programs that require a large aperture.
752(2005); http://dx.doi.org/10.1063/1.1893327View Description Hide Description
In this paper, I briefly summarize the basic ingredients for modeling stellar atmospheres. The progress in the numerical solution techniques has evolved in parallel to the rapid development of observing facilities. The modeling of stellar atmospheres in particular and stellar astrophysics in general are therefore important ingredients for our understanding of stellar, galactic and cosmic evolution.
752(2005); http://dx.doi.org/10.1063/1.1893328View Description Hide Description
SALT’s first generation instrumentation will be ideally suited to stellar astrophysical studies, both in our own Galaxy and in nearby galaxies. This paper will describe the design, capabilities and status of the instruments, emphasizing those modes and niches that will impact stellar astronomy. The first‐light ‘visible beam’ (320–900nm) instruments, the imaging camera, SALTICAM, and the imaging spectrograph, PFIS, are due to begin commissioning observations later in 2004/early 2005. The latter will be the work‐horse instrument on SALT in the near future, and contains many modes appropriate for stellar observational astronomy, namely low to medium resolution spectroscopy and spectropolarimetry, Fabry‐Perot imaging spectroscopy, narrow band imaging, and imaging polarimetry. Both instruments will support high time resolution observations, one of the niche areas of stellar astrophysics. The last of the first generation instruments will be a fibre‐fed double‐beam high resolution white‐pupil R4 échelle spectrograph, SALT HRS, designed for good stability, a range or resolutions and accurate background subtraction. The instrument is currently in its design phase, and construction will likely begin in early 2005, with an estimated delivery in 2007.
752(2005); http://dx.doi.org/10.1063/1.1893329View Description Hide Description
As part of its contribution to the SALT partnership, the University of Canterbury expects to build a fibre‐fed, high‐resolution stellar spectrograph with excellent wavelength stability. The design, with separate red and blue arms, is based on a dual R4 échelle grating with cross dispersion provided by Volume Phase Holographic Gratings. Separate fibres will permit simultaneous observation of target and sky; different fibre pairs and injection optics will provide three different resolving powers between ∼17 000 and 80 000. These properties are pertinent to a range of astrophysical problems of interest to both SALT partners and University of Canterbury astronomers.
752(2005); http://dx.doi.org/10.1063/1.1893330View Description Hide Description
The paper points out the importance of the recently discovered transiting planets and discusses the photometric searches for such extrasolar giant planets. The seven known transiting planets suggest a possible correlation between the masses and periods of the close‐in giant planets.
752(2005); http://dx.doi.org/10.1063/1.1893331View Description Hide Description
We present motivation and initial results of a large RV survey of K giants aimed at a detection of low‐mass companions. The survey, performed with the Hobby‐Eberly Telescope, utilizes high resolution (60,000) spectra for high precision radial velocity measurements. The primary goal of the survey is the selection of astrometrically stable reference stars for the Extrasolar Planet Interferometric Survey key project to be carried out with the Space Interferometry Mission.
752(2005); http://dx.doi.org/10.1063/1.1893332View Description Hide Description
The searching for ‘other worlds’ is one of the oldest well known scientific questions. With the first discovery of planets around the pulsar PSR1257+12 (Wolszczan & Frail 1992) and the main sequence star 51 Peg (Mayor & Queloz 1995), a new field of astronomy has been opened. Most of the planets have been found around main‐sequence solar‐mass stars. However in this investigation, we present our plan to search for planets around intermediate‐mass late G type giant stars (1.5 – 3M ⊙) with cooperation with Japanese astronomers and give the preliminary results of this research. A long‐term monitoring of the Doppler velocities of stars will be carried out with mid‐size telescopes at Okayama (Japan) and Xinglong (China).
752(2005); http://dx.doi.org/10.1063/1.1893333View Description Hide Description
Trans‐Neptunian objects (TNOs) represent a population of bodies that never approached the Sun and preserved information on the conditions in the primordial planetary nebula. Unfortunately, little is still known about their physical properties. Low resolution spectroscopy of TNOs can change this but it requires the largest, 8 – 10 m class telescopes to be used.
752(2005); http://dx.doi.org/10.1063/1.1893334View Description Hide Description
Speckle interferometry is a method for attainment high angular resolution using full aperture of the large telescope. We give a brief description of the main principles of the method and the history of its development at large telescopes. The main fields of application of the method are the binary and multiple star research, study of the circumstellar gas and dust structures both for young objects and for stars at the latest stages of their evolution. Stellar diameters of nearby supergiants can be measured in different bands using the largest world telescopes. We discuss the perspectives of the method adaptation at the telescopes with segmented mirrors.
752(2005); http://dx.doi.org/10.1063/1.1893335View Description Hide Description
Spectropolarimetry is a photon‐hungry technique that will reach fruition in the 8‐m telescope age. Here I summarize some of the stellar spectropolarimetric research that my collaborators and I have undertaken, with particular emphasis on the circumstellar environment of massive stars, symbiotic binaries, and star formation.
752(2005); http://dx.doi.org/10.1063/1.1893336View Description Hide Description
We present two classes of stars with yet unknown evolutionary phase: the B[e] supergiants and the so‐called unclassified B[e] stars. While the B[e] supergiants are luminous post‐main sequence stars with high mass progenitors, not much is known of the unclassified stars. We discuss how it might be possible to determine their evolutionary phases in the area of new large telescopes.
752(2005); http://dx.doi.org/10.1063/1.1893337View Description Hide Description
We show that DEBs can serve as excellent age and distance indicators for globular clusters. A short review of past surveys for eclipsing binaries in globular clusters is followed by presentation of the current status of the CASE project. A few selected systems from the CASE sample are discussed in some detail.
752(2005); http://dx.doi.org/10.1063/1.1893338View Description Hide Description
LAMOST is one of the Chinese national big science programs. As an all reflecting Schmidt telescope with an effective aperture of 4 meters, LAMOST has a field of view of 5 degrees. Its 4000 optical fibers can point to selected celestial objects automatically and link to 16 spectrographs, thus to obtain about 4000 spectra simultaneously. With the large field of view and multi‐fibers, LAMOST is efficient to collect huge number of stellar spectra, which leads us to propose using it to study our Milky Way galaxy.
Star Counts and Galactic Structure: The distribution of main sequence stars and giants in color‐color diagram752(2005); http://dx.doi.org/10.1063/1.1893339View Description Hide Description
Main sequence stars have good color‐magnitude relation to obtain distance which is the key to determine the structure of the Galaxy using the method of star counts. A model to mimic observation is made in this paper to infer a certain criteria to distinguish main sequence stars and giants.
752(2005); http://dx.doi.org/10.1063/1.1893340View Description Hide Description
There are many ways in which observations with large telescopes are improving our understanding of evolution on the Asymptotic Giant Branch. Perhaps more importantly AGB stars also offer huge potential to probe the nature of low‐ and intermediate‐mass populations over a very considerable range of distances and in a variety of environments. This review which is far from exhaustive, touches upon: the discovery of AGB stars in resolved stellar populations and their detailed investigation; the importance of abundances measurements — particularly those of technetium and lithium; the potential of kinematic studies and recent developments in interferometry. Finally the important role of AGB stars as probes of distant and unresolved populations is mentioned.
752(2005); http://dx.doi.org/10.1063/1.1893341View Description Hide Description
Planetary nebulae (PNe) are valuable objects to discuss a number of astrophysical issues. I illustrate here two topics in which the study of PNe has become particularly fashionable in the recent years, and which are best pursued using large telescopes.
The first one concerns the use of PNe to investigate one of the less understood phenomena in the evolution of solar‐type stars, namely the physics and time evolution of the strong mass loss that, at the end of the Asymptotic Giant Branch (AGB), spoils completely stars of their envelopes in only few 105 years.
The second one is the study of extragalactic PNe, a field that had a strong burst in the last years, as PNe have proven to be powerful test particles to discuss the cosmic distance scale, as well as the dynamics, stellar content, star formation history, and chemistry of galaxies and of the intergalactic medium.
752(2005); http://dx.doi.org/10.1063/1.1893342View Description Hide Description
Planetary nebulae (PNe) are known to possess a variety of small‐scale structures that are usually in a lower ionization state than the main body of the nebulae. The morphological and kinematic properties of these low‐ionization structures (LISs) vary from type to type in the sense that LISs can appear in the form of pairs of knots, filaments, jets, and isolated features moving with velocities that either do not differ substantially from that of the ambient nebula, or instead move supersonically through the environment. The high‐velocity jets and pairs of knots, also known as FLIERs, are likely to be shock‐excited. So far, most of the FLIERs analyzed with ground‐based small and medium telescopes, as well as with the HST, do not show the expected shock‐excited features —either the bow‐shock geometry or the shock excited emission lines. In this talk we discuss the crucial problem of the excitation mechanisms of FLIERs —through the comparison of jets and knots of NGC 7009 and K 4‐47— and what might be the contribution of large telescopes.
752(2005); http://dx.doi.org/10.1063/1.1893343View Description Hide Description
High resolution, high signal to noise, echelle spectra of some symbiotic stars were obtained in five runs from 1999 to 2004. The metal abundance of HD154791, which contains a neutron‐star companion, is similar to other normal giants with same spectral type. The stellar surface parameters of the cool component of AG Dra have been calculated utilizing the Kurucz atmosphere model and assuming the local thermodynamic equilibrium. We have obtained the effective temperature of 3960 ± 50 K, the surface gravity of log(g) = 0.85 ± 0.30, and the metal abundance of [Fe/H]= −1.5. Combining the results with other authors’ observations, we conclude that the cool component of AG Dra may be evolved to early AGB.
752(2005); http://dx.doi.org/10.1063/1.1893344View Description Hide Description
We propose to obtain high resolution infrared spectra at the 8.3 m Gemini South telescope to examine the nature of the cool components of symbiotic stars in the Magellanic Clouds. Physical parameters such as temperature, luminosity, mass loss rate and chemical abundances can provide information about their evolutionary stage and binary structure.